Another Olympus E-M1 and SONY a7 walkabout test, high ISO

Started 10 months ago | Discussions
Anders W
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Re: Thanks for the truth!
In reply to blue_skies, 10 months ago

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Lab D wrote:

blue_skies wrote:

Lab D wrote:

blue_skies wrote:

Lab D wrote:

skyglider wrote:

blue_skies wrote:

skyglider wrote:

blue_skies wrote:

How so: in equivalence terms, the Oly 12-40/f2.8 becomes 24-80/f5.6 versus the Sony 24-70/f4.0?

Hi Henry,

I understand how the Oly 12-40mm is equivalent to 24-80mm in 35mm terms because of the 2x crop factor of the micro 4/3 sensor. But AFAIK, the aperture remains the same.

IOW, if an Oly 12mm lens could be used on a full frame (35mm) sensor, only the center 1/4 of the sensor area would be illuminated which is equivalent to 1/2 the horizontal and vertical pixels. Thus the crop factor of 2x. But the aperture remains the same so the same amount of light is hitting that portion of the sensor by the F2.8 aperture. So the aperture does "not" become equivalent to a F5.6 aperture.

Is my understanding incorrect?

Thanks,
Sky

Hi Sky, no your understanding is correct.

In terms of ISO, aperture and shutter speed, the exposure is the SAME on the small and the larger sensor.

If you are after (fast) shutter speed, you only care about the lens speed, and your thinking is correct.

But in terms of noise, the larger sensor allows to operate at a much higher ISO level and produce the same amount of noise: in m43/FF this is a 4x ratio, or 2 stops. This means that eg. m43 at ISO 1,000 is as noise as FF at ISO 4,000.

So, if you want to produce comparable images, you would shoot the FF image with two stops slower aperture and at two stops higher ISO. This is equivalent exposure.

Ironically, the same metric applies to DOF - you roughly see about the same DOF in both images as well.

Thus, shooting the Oly at 12mm f/2.8, ISO 1,000 as 1/60th is equivalent to shooting the Sony at f/5.6, ISO 4,000 and 1/60th. Aside from the resolution, the two images will appear similar.

If you use the same exposure on both, you are comparing the FF at ISO 1,000 versus the Oly at ISO 1,000. The FF image will have a lot less noise, ie. be much cleaner, but the DOF will also be reduced. The images are not equivalent at that point.

On FF you can trade noise for DOF, assuming you have a fast lens. There is a 2 stop delta to play with.

In the example, using the Sony lens at f/4.0 implies that the ISO goes to 2,000. This is one stop below the equivalent values of f/5.6 and ISO 4,000, so, with more shallow DOF, you will have a less noisy image on the FF.

-- hide signature --

Cheers,
Henry

Hi Henry,

I think I understand your point now. I wondered how many stops difference there was between a micro 4/3 sensor verses a full frame sensor. Now I know it's a 4x ratio or 2 stops difference.

That only applies for Depth of field. If you check the results from DxO tests, the difference is much less. A good example is dynamic range where the E-M1 is only about 1/2 stop different than the A7 for most of the ISO settings DxO tested.

Remember if you need F/2.8, 1/60th sec shutter speed, and ISO800 on the E-M1, you will need the SAME settings on an A7, a Nikon 1 and a Sony RX100. It would even be the same on your smartphone!

Again, exposure = exposure and equivalence = equivalence.

And you know in this case equivalance does not tell us the facts. Admit it, there is NOT a 2 stop difference for noise or dynamic range at almsot all the ISOs DxO tested.

Just admit the truth for once.

Henry showing the difference between sensors

-- hide signature --

Cheers,
Henry

You are right with the DxO link. The difference is really negligible. There is not a 2 stop difference almost all of time here.

?????

Please go take ISO 6400 pictures with your EM1 then

You conveniently deleted that I stated that it is immaterial whether it is 2x, or 1.65x, or 1.5x stops.

Where did you state that? And of course it isn't immaterial. If it's less than two stops (as it certainly is), MFT has an advantage with regard to signal-noise performance for equivalent images (same DoF, same shutter speed, different exposure, different ISOs).

http://www.dpreview.com/forums/post/53010416

"If DxO points out that it is 1.65x stops or 1.5x stops, it does NOT CHANGE the general thoughts"

It certainly does. The facts are as follows:

1. With respect to exposure, that is, the amount of light falling on the sensor per area unit (e.g., per square millimeter), f/2.8 on MFT is equivalent to f/2.8 on FF.

2. With respect to the total amount of light falling on the sensor, DoF, and diffraction, f/2.8 on MFT is equivalent to f/5.6 on FF (assuming, with regard to DoF, that the AoV and the focus distance is the same).

3. The total amount of light falling on the sensor is not the only determinant of signal-noise performance. What additionally matters is the quantum efficiency and the read-noise performance. In these regards, smaller sensors tend to be more efficient than larger sensors, as illustrated, for example by the graph posted by Lab D. Consequently, the difference between the A7/A7R and the E-M1 with regard to signal-noise performance at the same exposure is less than two stops.

You consistently overlook point 3 in spite of the fact that it has repeatedly been pointed out to you for months.

Not at all Anders, you have elaborated on this in the past,

Nevertheless, you overlook it time and again.

and the difference, even per DxO, they rate the ISO performance for the cameras as EM1/A7/A7r as 757/2248/2746. Two stops would have been 3028. So we all agree?

Not quite. While these figures too show the difference to be less than two stops, they underestimate the actual advantage of the E-M1 for equivalent images. The DR curve posted by Lab D provides a better indication with regard to shadow noise, which in turn is the most apparent problem in high ISO shooting. What the curves indicate is that the E-M1 is about 1.5 stops ahead of the A7/A7R for equivalent images (DoF held constant) and about 0.5 EV behind at the same exposure (and different DoF).

Sure, MFT has a 'technical advantage' but the image is worse - my eyes don't deceive me - download Daniel's newly uploaded full-image side-by-side and see for yourself.

Your eyes may not deceive you but your brain certainly does. Daniel's images are not equivalent images (see definition above). Rather they are images shot at the same exposure, in which case the A7 can be expected to do better with regard to signal-noise performance (although less than two stops better) but at the expense of two stops less worth of DoF.

And this is my argument: users shoot alike Daniel, and this produces images that may or may not be equivalent

An argument for what? It is certainly not a relevant objection to the point Lab D and I were making.

- even in Daniel's case he tried to match FL, aperture and framing as best as he could. Yet the resulting images speak for themselves.

As a rule (his practice was not entirely consistent) he matched f-stop but as we know that does not give equal DoF. If he had chosen to shoot equivalent images, as he might well have done, the outcome with regard to signal-noise performance would have been different.

It is immaterial, imho, as I would not use a smaller sensor camera at higher ISO. Why not? Because the image quality degrades too much. I would rather use longer exposure and lower ISO, if possible.

When you are in a position to freely increase the length of the exposure (because the scene is static), you are also free to bracket exposure and merge/align multiple images. This makes sensor performance a moot point.

When you are not in a position to do so, MFT has the advantage with regard to signal-noise performance for equivalent images.

See the image above, sure, it can be improved upon, but as Daniel said "the way a user would do it". Clearly the images are not similar in IQ, neither at ISO 100 nor at ISO 3200.

Again, the images above are not equivalent.

They are not, and I expected the high ISO image to perform better on the larger sensor. Again, read noise and pixel noise are not the same, and the larger sensor has larger pixels.

I don't think anyone has different expections than you in that regard. If you give the larger sensor the same exposure, it will have an advantage with regard to signal-noise performance at the expense of DoF.

But the low ISO image surprised me, I would have expected the ISO 100 images to be much closer to each other in IQ than they in fact are.

This is a scene with extreme dynamic range. Here's how to do such a scene better from a signal-noise point of view than either an E-M1 or an A7/A7R can manage in a single shot (nine shots with the E-M5 and the 12/2 at f/4, with shutter speeds varying from 1/8 s to 30 s, base ISO, merged and aligned in PP).

And we have had this discussion so many times already. Why the nitpicking?

Because you are not admitting the truth.

What truth?

The truth contained in my point 3 above.

Which shows that the ratio is not proportional to sensor size. It still confirms that larger sensors perform better.

No it doesn't. Rather it confirms that the smaller sensors do better from a signal-noise point of view when DoF is held constant. In order to do better from a signal-noise point of view, the larger sensor has to sacrifice DoF.

Let me explain: per your point, an 'equivalent' exposure on the smaller sensor would be of higher IQ. But the larger sensor allows more noise/DOF trade-off which results in a higher IQ image (but non-equivalent), at the cost of shallow DOF (which may or may not matter).

As far as I am concerned, DoF is just as much a part of IQ as is signal-noise performance.

I thank Daniel for uploading the images - they speak for themselves.

Only if you know how to interpret them correctly and you just showed you didn't.

Which image would you hang on the wall then? Perhaps not equivalent, but one camera is cleanly cleaner.

And the other clearly has better DoF. In most of the sample images, the DoF provided by the A7 is too shallow based on my preferences.

Technical slides do not tell this story, and in the analysis we get lost in sensor efficiency, not image IQ.

"Technical slides" (I'd call them diagrams) do tell the story as long as they reflect relevant and accurate measurements (as they do in this case). And sensor efficiency has implications for image quality as indicated by my point 3 above.

Yes, and you repeat this as often as you can. But to my point - show side-by-side images, let them speak. We have side-by-side images here to point at, and I would definitely pick the larger sensor camera.

I have no objections to looking at images side by side. But those we got here do not show all the relevant comparisons and my choice between those we can see would be different than yours. As I said, I find the DoF of the A7 images too shallow in most cases (1st, 2nd, 4th, and 5th pair). Pair 3 is a failure (wrong focus on the MFT image) and for pair 6, DoF is irrelevant.

Change the venue and shoot people walking at low ISO, I would expect the smaller sensor camera to pull ahead.

On what grounds do you think so?

Like I said, both cameras have pros and cons, but low light & high ISO (and shallow DOF) are not the smaller sensor's strong points.

The point here is rather that the smaller sensor is ahead in low light/high ISO whenever DoF is in short supply.

Lower the ISO, and both cameras are great. They both have their pros and cons.

They both have their pros and cons, but it is important to be factually correct about what those pros and cons are.

See my comments here: http://www.dpreview.com/forums/post/53009228

Pros and cons are subject to an individual bias.

The facts are objective, the evaluation of those facts is not.

Then show us how to shoot the M1? Obviously, users don't know how to.

What specifically makes you think they don't?

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Rens
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Re: Another Olympus E-M1 and SONY a7 walkabout test, high ISO
In reply to Daniel Wee, 10 months ago

Daniel Wee wrote:

I used the default sharpening in LR for the post-processing. Unfortunately I didn't have time to optimize them - I thought keeping them default would at least let us know where we can go from there.

First of all, thanks for taking the time to do these comparisons.  And ignore the nit-picking, I find your approach to be fine.

Regarding sharpening, I don't have the EM1 but I have the similar EM5.  And in some way even RAW files from it seem to have had an odd sharpening or contrast applied.  So that foliage against the sky, for example, can seem too speckly.

When opening in ACR I find reducing the 'clarity' to varying extents helps.  Otherwise, even default sharpening can seem oddly over-sharpened.

Thanks again,
Rens

There are optimists and there are realists

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photofan1986
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Re: Another Olympus E-M1 and SONY a7 walkabout test, high ISO
In reply to captura, 10 months ago

captura wrote:

I don't agree. They are equal.

Sorry about your cataract

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photofan1986
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Re: Another Olympus E-M1 and SONY a7 walkabout test, high ISO
In reply to Daniel Wee, 10 months ago

Thank you for the effort. Those are much better indeed!

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Lab D
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He'll never learn
In reply to Anders W, 10 months ago

The service that DxO provides for sensors is that you can look at the graphs and determine how a sensor will perform at a given ISO.  Since some systems have slower zoom lenses, you can also compare while adjusting for the differences between lens apertures by look at different ISOs.

So, when you look at the A7/A7R and the E-M1 for ISO1600, you can easily see the difference in DR is about 1/2 stop.  The "overall" score is obviously not helpful here and if anything is wrong for that situation.  Now if you want to compare the cameras with their fastest available native zooms, you can read the E-M1 line at ISO800 and compare to the A7 at ISO1600.  Again this is far more accurate than trying to use those overall scores.

It frustrates me when newbies only look at the overall DxO scores and don’t understand what they mean.  What is worse is when they don’t look at the actual findings which better represent reality and all the specific situations you may run into.

We know that some here don’t want to know the truth and have other motives.

btw, you are right.  When people mention "equivalence" they ar talking about using the same DoF.  When you do that these days the smaller sensor wins for SNR and other measurements.  As long as the smaller sensor can give you the shallow DoF you want, it will perform better than the larger one IMHO.

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Anders W
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Re: He'll never learn
In reply to Lab D, 10 months ago

Lab D wrote:

As long as the smaller sensor can give you the shallow DoF you want, it will perform better than the larger one IMHO.

Precisely.

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bluevellet
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My quick take
In reply to Daniel Wee, 10 months ago

The FE 55mm has really nice bokeh. The A7(r ) camera doesn't handle red well,

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blue_skies
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Re: Thanks for the truth!
In reply to Anders W, 10 months ago

Anders W wrote:

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Lab D wrote:

blue_skies wrote:

Lab D wrote:

blue_skies wrote:

Lab D wrote:

skyglider wrote:

blue_skies wrote:

skyglider wrote:

blue_skies wrote:

How so: in equivalence terms, the Oly 12-40/f2.8 becomes 24-80/f5.6 versus the Sony 24-70/f4.0?

Hi Henry,

I understand how the Oly 12-40mm is equivalent to 24-80mm in 35mm terms because of the 2x crop factor of the micro 4/3 sensor. But AFAIK, the aperture remains the same.

IOW, if an Oly 12mm lens could be used on a full frame (35mm) sensor, only the center 1/4 of the sensor area would be illuminated which is equivalent to 1/2 the horizontal and vertical pixels. Thus the crop factor of 2x. But the aperture remains the same so the same amount of light is hitting that portion of the sensor by the F2.8 aperture. So the aperture does "not" become equivalent to a F5.6 aperture.

Is my understanding incorrect?

Thanks,
Sky

Hi Sky, no your understanding is correct.

In terms of ISO, aperture and shutter speed, the exposure is the SAME on the small and the larger sensor.

If you are after (fast) shutter speed, you only care about the lens speed, and your thinking is correct.

But in terms of noise, the larger sensor allows to operate at a much higher ISO level and produce the same amount of noise: in m43/FF this is a 4x ratio, or 2 stops. This means that eg. m43 at ISO 1,000 is as noise as FF at ISO 4,000.

So, if you want to produce comparable images, you would shoot the FF image with two stops slower aperture and at two stops higher ISO. This is equivalent exposure.

Ironically, the same metric applies to DOF - you roughly see about the same DOF in both images as well.

Thus, shooting the Oly at 12mm f/2.8, ISO 1,000 as 1/60th is equivalent to shooting the Sony at f/5.6, ISO 4,000 and 1/60th. Aside from the resolution, the two images will appear similar.

If you use the same exposure on both, you are comparing the FF at ISO 1,000 versus the Oly at ISO 1,000. The FF image will have a lot less noise, ie. be much cleaner, but the DOF will also be reduced. The images are not equivalent at that point.

On FF you can trade noise for DOF, assuming you have a fast lens. There is a 2 stop delta to play with.

In the example, using the Sony lens at f/4.0 implies that the ISO goes to 2,000. This is one stop below the equivalent values of f/5.6 and ISO 4,000, so, with more shallow DOF, you will have a less noisy image on the FF.

-- hide signature --

Cheers,
Henry

Hi Henry,

I think I understand your point now. I wondered how many stops difference there was between a micro 4/3 sensor verses a full frame sensor. Now I know it's a 4x ratio or 2 stops difference.

That only applies for Depth of field. If you check the results from DxO tests, the difference is much less. A good example is dynamic range where the E-M1 is only about 1/2 stop different than the A7 for most of the ISO settings DxO tested.

Remember if you need F/2.8, 1/60th sec shutter speed, and ISO800 on the E-M1, you will need the SAME settings on an A7, a Nikon 1 and a Sony RX100. It would even be the same on your smartphone!

Again, exposure = exposure and equivalence = equivalence.

And you know in this case equivalance does not tell us the facts. Admit it, there is NOT a 2 stop difference for noise or dynamic range at almsot all the ISOs DxO tested.

Just admit the truth for once.

Henry showing the difference between sensors

-- hide signature --

Cheers,
Henry

You are right with the DxO link. The difference is really negligible. There is not a 2 stop difference almost all of time here.

?????

Please go take ISO 6400 pictures with your EM1 then

You conveniently deleted that I stated that it is immaterial whether it is 2x, or 1.65x, or 1.5x stops.

Where did you state that? And of course it isn't immaterial. If it's less than two stops (as it certainly is), MFT has an advantage with regard to signal-noise performance for equivalent images (same DoF, same shutter speed, different exposure, different ISOs).

http://www.dpreview.com/forums/post/53010416

"If DxO points out that it is 1.65x stops or 1.5x stops, it does NOT CHANGE the general thoughts"

It certainly does. The facts are as follows:

1. With respect to exposure, that is, the amount of light falling on the sensor per area unit (e.g., per square millimeter), f/2.8 on MFT is equivalent to f/2.8 on FF.

2. With respect to the total amount of light falling on the sensor, DoF, and diffraction, f/2.8 on MFT is equivalent to f/5.6 on FF (assuming, with regard to DoF, that the AoV and the focus distance is the same).

3. The total amount of light falling on the sensor is not the only determinant of signal-noise performance. What additionally matters is the quantum efficiency and the read-noise performance. In these regards, smaller sensors tend to be more efficient than larger sensors, as illustrated, for example by the graph posted by Lab D. Consequently, the difference between the A7/A7R and the E-M1 with regard to signal-noise performance at the same exposure is less than two stops.

You consistently overlook point 3 in spite of the fact that it has repeatedly been pointed out to you for months.

Not at all Anders, you have elaborated on this in the past,

Nevertheless, you overlook it time and again.

and the difference, even per DxO, they rate the ISO performance for the cameras as EM1/A7/A7r as 757/2248/2746. Two stops would have been 3028. So we all agree?

Not quite. While these figures too show the difference to be less than two stops, they underestimate the actual advantage of the E-M1 for equivalent images. The DR curve posted by Lab D provides a better indication with regard to shadow noise, which in turn is the most apparent problem in high ISO shooting. What the curves indicate is that the E-M1 is about 1.5 stops ahead of the A7/A7R for equivalent images (DoF held constant) and about 0.5 EV behind at the same exposure (and different DoF).

Sure, MFT has a 'technical advantage' but the image is worse - my eyes don't deceive me - download Daniel's newly uploaded full-image side-by-side and see for yourself.

Your eyes may not deceive you but your brain certainly does. Daniel's images are not equivalent images (see definition above). Rather they are images shot at the same exposure, in which case the A7 can be expected to do better with regard to signal-noise performance (although less than two stops better) but at the expense of two stops less worth of DoF.

And this is my argument: users shoot alike Daniel, and this produces images that may or may not be equivalent

An argument for what? It is certainly not a relevant objection to the point Lab D and I were making.

- even in Daniel's case he tried to match FL, aperture and framing as best as he could. Yet the resulting images speak for themselves.

As a rule (his practice was not entirely consistent) he matched f-stop but as we know that does not give equal DoF. If he had chosen to shoot equivalent images, as he might well have done, the outcome with regard to signal-noise performance would have been different.

It is immaterial, imho, as I would not use a smaller sensor camera at higher ISO. Why not? Because the image quality degrades too much. I would rather use longer exposure and lower ISO, if possible.

When you are in a position to freely increase the length of the exposure (because the scene is static), you are also free to bracket exposure and merge/align multiple images. This makes sensor performance a moot point.

When you are not in a position to do so, MFT has the advantage with regard to signal-noise performance for equivalent images.

See the image above, sure, it can be improved upon, but as Daniel said "the way a user would do it". Clearly the images are not similar in IQ, neither at ISO 100 nor at ISO 3200.

Again, the images above are not equivalent.

They are not, and I expected the high ISO image to perform better on the larger sensor. Again, read noise and pixel noise are not the same, and the larger sensor has larger pixels.

I don't think anyone has different expections than you in that regard. If you give the larger sensor the same exposure, it will have an advantage with regard to signal-noise performance at the expense of DoF.

But the low ISO image surprised me, I would have expected the ISO 100 images to be much closer to each other in IQ than they in fact are.

This is a scene with extreme dynamic range. Here's how to do such a scene better from a signal-noise point of view than either an E-M1 or an A7/A7R can manage in a single shot (nine shots with the E-M5 and the 12/2 at f/4, with shutter speeds varying from 1/8 s to 30 s, base ISO, merged and aligned in PP).

And we have had this discussion so many times already. Why the nitpicking?

Because you are not admitting the truth.

What truth?

The truth contained in my point 3 above.

Which shows that the ratio is not proportional to sensor size. It still confirms that larger sensors perform better.

No it doesn't. Rather it confirms that the smaller sensors do better from a signal-noise point of view when DoF is held constant. In order to do better from a signal-noise point of view, the larger sensor has to sacrifice DoF.

Let me explain: per your point, an 'equivalent' exposure on the smaller sensor would be of higher IQ. But the larger sensor allows more noise/DOF trade-off which results in a higher IQ image (but non-equivalent), at the cost of shallow DOF (which may or may not matter).

As far as I am concerned, DoF is just as much a part of IQ as is signal-noise performance.

I thank Daniel for uploading the images - they speak for themselves.

Only if you know how to interpret them correctly and you just showed you didn't.

Which image would you hang on the wall then? Perhaps not equivalent, but one camera is cleanly cleaner.

And the other clearly has better DoF. In most of the sample images, the DoF provided by the A7 is too shallow based on my preferences.

Technical slides do not tell this story, and in the analysis we get lost in sensor efficiency, not image IQ.

"Technical slides" (I'd call them diagrams) do tell the story as long as they reflect relevant and accurate measurements (as they do in this case). And sensor efficiency has implications for image quality as indicated by my point 3 above.

Yes, and you repeat this as often as you can. But to my point - show side-by-side images, let them speak. We have side-by-side images here to point at, and I would definitely pick the larger sensor camera.

I have no objections to looking at images side by side. But those we got here do not show all the relevant comparisons and my choice between those we can see would be different than yours. As I said, I find the DoF of the A7 images too shallow in most cases (1st, 2nd, 4th, and 5th pair). Pair 3 is a failure (wrong focus on the MFT image) and for pair 6, DoF is irrelevant.

Change the venue and shoot people walking at low ISO, I would expect the smaller sensor camera to pull ahead.

On what grounds do you think so?

Like I said, both cameras have pros and cons, but low light & high ISO (and shallow DOF) are not the smaller sensor's strong points.

The point here is rather that the smaller sensor is ahead in low light/high ISO whenever DoF is in short supply.

Lower the ISO, and both cameras are great. They both have their pros and cons.

They both have their pros and cons, but it is important to be factually correct about what those pros and cons are.

See my comments here: http://www.dpreview.com/forums/post/53009228

Pros and cons are subject to an individual bias.

The facts are objective, the evaluation of those facts is not.

Then show us how to shoot the M1? Obviously, users don't know how to.

What specifically makes you think they don't?

I like the image that you included. But I am not that fast in rejecting an image because of shallow DOF - there are (lots of) times when it works, but not always.

As to this debate - 32 posts and counting merely because I (dared) compared the 4x sensor difference to roughly 2 stops? And perhaps also because I dared looking at actual images, rather than the theoretical perfect ones?

Ok, I get it, you guys are relentless, and will never stop.

Can we call this a dead horse now?

-- hide signature --

Cheers,
Henry

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blue_skies
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Re: He'll never learn
In reply to Lab D, 10 months ago

Lab D wrote:

The service that DxO provides for sensors is that you can look at the graphs and determine how a sensor will perform at a given ISO. Since some systems have slower zoom lenses, you can also compare while adjusting for the differences between lens apertures by look at different ISOs.

So, when you look at the A7/A7R and the E-M1 for ISO1600, you can easily see the difference in DR is about 1/2 stop. The "overall" score is obviously not helpful here and if anything is wrong for that situation. Now if you want to compare the cameras with their fastest available native zooms, you can read the E-M1 line at ISO800 and compare to the A7 at ISO1600. Again this is far more accurate than trying to use those overall scores.

It frustrates me when newbies only look at the overall DxO scores and don’t understand what they mean. What is worse is when they don’t look at the actual findings which better represent reality and all the specific situations you may run into.

Your frustration is loud and clear.

Also, many of your posts frustrate others, but I guess that that does not count....

We know that some here don’t want to know the truth and have other motives.

btw, you are right. When people mention "equivalence" they ar talking about using the same DoF. When you do that these days the smaller sensor wins for SNR and other measurements. As long as the smaller sensor can give you the shallow DoF you want, it will perform better than the larger one IMHO.

It is simply to hard to have a conversation with you, you constantly keep bringing up different points and changing topics.

Heck, I even agree with the last sentence you wrote, nothing wrong with it. But I don't know how to construct a constructive dialogue with you

Peace

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Henry

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Anders W
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Re: Thanks for the truth!
In reply to blue_skies, 10 months ago

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Lab D wrote:

blue_skies wrote:

Lab D wrote:

blue_skies wrote:

Lab D wrote:

skyglider wrote:

blue_skies wrote:

skyglider wrote:

blue_skies wrote:

How so: in equivalence terms, the Oly 12-40/f2.8 becomes 24-80/f5.6 versus the Sony 24-70/f4.0?

Hi Henry,

I understand how the Oly 12-40mm is equivalent to 24-80mm in 35mm terms because of the 2x crop factor of the micro 4/3 sensor. But AFAIK, the aperture remains the same.

IOW, if an Oly 12mm lens could be used on a full frame (35mm) sensor, only the center 1/4 of the sensor area would be illuminated which is equivalent to 1/2 the horizontal and vertical pixels. Thus the crop factor of 2x. But the aperture remains the same so the same amount of light is hitting that portion of the sensor by the F2.8 aperture. So the aperture does "not" become equivalent to a F5.6 aperture.

Is my understanding incorrect?

Thanks,
Sky

Hi Sky, no your understanding is correct.

In terms of ISO, aperture and shutter speed, the exposure is the SAME on the small and the larger sensor.

If you are after (fast) shutter speed, you only care about the lens speed, and your thinking is correct.

But in terms of noise, the larger sensor allows to operate at a much higher ISO level and produce the same amount of noise: in m43/FF this is a 4x ratio, or 2 stops. This means that eg. m43 at ISO 1,000 is as noise as FF at ISO 4,000.

So, if you want to produce comparable images, you would shoot the FF image with two stops slower aperture and at two stops higher ISO. This is equivalent exposure.

Ironically, the same metric applies to DOF - you roughly see about the same DOF in both images as well.

Thus, shooting the Oly at 12mm f/2.8, ISO 1,000 as 1/60th is equivalent to shooting the Sony at f/5.6, ISO 4,000 and 1/60th. Aside from the resolution, the two images will appear similar.

If you use the same exposure on both, you are comparing the FF at ISO 1,000 versus the Oly at ISO 1,000. The FF image will have a lot less noise, ie. be much cleaner, but the DOF will also be reduced. The images are not equivalent at that point.

On FF you can trade noise for DOF, assuming you have a fast lens. There is a 2 stop delta to play with.

In the example, using the Sony lens at f/4.0 implies that the ISO goes to 2,000. This is one stop below the equivalent values of f/5.6 and ISO 4,000, so, with more shallow DOF, you will have a less noisy image on the FF.

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Henry

Hi Henry,

I think I understand your point now. I wondered how many stops difference there was between a micro 4/3 sensor verses a full frame sensor. Now I know it's a 4x ratio or 2 stops difference.

That only applies for Depth of field. If you check the results from DxO tests, the difference is much less. A good example is dynamic range where the E-M1 is only about 1/2 stop different than the A7 for most of the ISO settings DxO tested.

Remember if you need F/2.8, 1/60th sec shutter speed, and ISO800 on the E-M1, you will need the SAME settings on an A7, a Nikon 1 and a Sony RX100. It would even be the same on your smartphone!

Again, exposure = exposure and equivalence = equivalence.

And you know in this case equivalance does not tell us the facts. Admit it, there is NOT a 2 stop difference for noise or dynamic range at almsot all the ISOs DxO tested.

Just admit the truth for once.

Henry showing the difference between sensors

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Henry

You are right with the DxO link. The difference is really negligible. There is not a 2 stop difference almost all of time here.

?????

Please go take ISO 6400 pictures with your EM1 then

You conveniently deleted that I stated that it is immaterial whether it is 2x, or 1.65x, or 1.5x stops.

Where did you state that? And of course it isn't immaterial. If it's less than two stops (as it certainly is), MFT has an advantage with regard to signal-noise performance for equivalent images (same DoF, same shutter speed, different exposure, different ISOs).

http://www.dpreview.com/forums/post/53010416

"If DxO points out that it is 1.65x stops or 1.5x stops, it does NOT CHANGE the general thoughts"

It certainly does. The facts are as follows:

1. With respect to exposure, that is, the amount of light falling on the sensor per area unit (e.g., per square millimeter), f/2.8 on MFT is equivalent to f/2.8 on FF.

2. With respect to the total amount of light falling on the sensor, DoF, and diffraction, f/2.8 on MFT is equivalent to f/5.6 on FF (assuming, with regard to DoF, that the AoV and the focus distance is the same).

3. The total amount of light falling on the sensor is not the only determinant of signal-noise performance. What additionally matters is the quantum efficiency and the read-noise performance. In these regards, smaller sensors tend to be more efficient than larger sensors, as illustrated, for example by the graph posted by Lab D. Consequently, the difference between the A7/A7R and the E-M1 with regard to signal-noise performance at the same exposure is less than two stops.

You consistently overlook point 3 in spite of the fact that it has repeatedly been pointed out to you for months.

Not at all Anders, you have elaborated on this in the past,

Nevertheless, you overlook it time and again.

and the difference, even per DxO, they rate the ISO performance for the cameras as EM1/A7/A7r as 757/2248/2746. Two stops would have been 3028. So we all agree?

Not quite. While these figures too show the difference to be less than two stops, they underestimate the actual advantage of the E-M1 for equivalent images. The DR curve posted by Lab D provides a better indication with regard to shadow noise, which in turn is the most apparent problem in high ISO shooting. What the curves indicate is that the E-M1 is about 1.5 stops ahead of the A7/A7R for equivalent images (DoF held constant) and about 0.5 EV behind at the same exposure (and different DoF).

Sure, MFT has a 'technical advantage' but the image is worse - my eyes don't deceive me - download Daniel's newly uploaded full-image side-by-side and see for yourself.

Your eyes may not deceive you but your brain certainly does. Daniel's images are not equivalent images (see definition above). Rather they are images shot at the same exposure, in which case the A7 can be expected to do better with regard to signal-noise performance (although less than two stops better) but at the expense of two stops less worth of DoF.

And this is my argument: users shoot alike Daniel, and this produces images that may or may not be equivalent

An argument for what? It is certainly not a relevant objection to the point Lab D and I were making.

- even in Daniel's case he tried to match FL, aperture and framing as best as he could. Yet the resulting images speak for themselves.

As a rule (his practice was not entirely consistent) he matched f-stop but as we know that does not give equal DoF. If he had chosen to shoot equivalent images, as he might well have done, the outcome with regard to signal-noise performance would have been different.

It is immaterial, imho, as I would not use a smaller sensor camera at higher ISO. Why not? Because the image quality degrades too much. I would rather use longer exposure and lower ISO, if possible.

When you are in a position to freely increase the length of the exposure (because the scene is static), you are also free to bracket exposure and merge/align multiple images. This makes sensor performance a moot point.

When you are not in a position to do so, MFT has the advantage with regard to signal-noise performance for equivalent images.

See the image above, sure, it can be improved upon, but as Daniel said "the way a user would do it". Clearly the images are not similar in IQ, neither at ISO 100 nor at ISO 3200.

Again, the images above are not equivalent.

They are not, and I expected the high ISO image to perform better on the larger sensor. Again, read noise and pixel noise are not the same, and the larger sensor has larger pixels.

I don't think anyone has different expections than you in that regard. If you give the larger sensor the same exposure, it will have an advantage with regard to signal-noise performance at the expense of DoF.

But the low ISO image surprised me, I would have expected the ISO 100 images to be much closer to each other in IQ than they in fact are.

This is a scene with extreme dynamic range. Here's how to do such a scene better from a signal-noise point of view than either an E-M1 or an A7/A7R can manage in a single shot (nine shots with the E-M5 and the 12/2 at f/4, with shutter speeds varying from 1/8 s to 30 s, base ISO, merged and aligned in PP).

And we have had this discussion so many times already. Why the nitpicking?

Because you are not admitting the truth.

What truth?

The truth contained in my point 3 above.

Which shows that the ratio is not proportional to sensor size. It still confirms that larger sensors perform better.

No it doesn't. Rather it confirms that the smaller sensors do better from a signal-noise point of view when DoF is held constant. In order to do better from a signal-noise point of view, the larger sensor has to sacrifice DoF.

Let me explain: per your point, an 'equivalent' exposure on the smaller sensor would be of higher IQ. But the larger sensor allows more noise/DOF trade-off which results in a higher IQ image (but non-equivalent), at the cost of shallow DOF (which may or may not matter).

As far as I am concerned, DoF is just as much a part of IQ as is signal-noise performance.

I thank Daniel for uploading the images - they speak for themselves.

Only if you know how to interpret them correctly and you just showed you didn't.

Which image would you hang on the wall then? Perhaps not equivalent, but one camera is cleanly cleaner.

And the other clearly has better DoF. In most of the sample images, the DoF provided by the A7 is too shallow based on my preferences.

Technical slides do not tell this story, and in the analysis we get lost in sensor efficiency, not image IQ.

"Technical slides" (I'd call them diagrams) do tell the story as long as they reflect relevant and accurate measurements (as they do in this case). And sensor efficiency has implications for image quality as indicated by my point 3 above.

Yes, and you repeat this as often as you can. But to my point - show side-by-side images, let them speak. We have side-by-side images here to point at, and I would definitely pick the larger sensor camera.

I have no objections to looking at images side by side. But those we got here do not show all the relevant comparisons and my choice between those we can see would be different than yours. As I said, I find the DoF of the A7 images too shallow in most cases (1st, 2nd, 4th, and 5th pair). Pair 3 is a failure (wrong focus on the MFT image) and for pair 6, DoF is irrelevant.

Change the venue and shoot people walking at low ISO, I would expect the smaller sensor camera to pull ahead.

On what grounds do you think so?

Like I said, both cameras have pros and cons, but low light & high ISO (and shallow DOF) are not the smaller sensor's strong points.

The point here is rather that the smaller sensor is ahead in low light/high ISO whenever DoF is in short supply.

Lower the ISO, and both cameras are great. They both have their pros and cons.

They both have their pros and cons, but it is important to be factually correct about what those pros and cons are.

See my comments here: http://www.dpreview.com/forums/post/53009228

Pros and cons are subject to an individual bias.

The facts are objective, the evaluation of those facts is not.

Then show us how to shoot the M1? Obviously, users don't know how to.

What specifically makes you think they don't?

I like the image that you included. But I am not that fast in rejecting an image because of shallow DOF - there are (lots of) times when it works, but not always.

As to this debate - 32 posts and counting merely because I (dared) compared the 4x sensor difference to roughly 2 stops?

It wouldn't have had to be 32 posts if you had recognized right away that what you said in the post to which I link below was in some important regards wrong:

http://www.dpreview.com/forums/post/53009777

Even better would have been if you had spelled out the actual truth from the beginning. I hope that you will eventually learn to do that.

And perhaps also because I dared looking at actual images, rather than the theoretical perfect ones?

Certainly not. I have nothing against looking at images. Both diagrams of measurements and actual images are useful when it comes to understanding things like those we are discussing here.

Ok, I get it, you guys are relentless, and will never stop.

We are only as relentless as you force us to be.

Can we call this a dead horse now?

While a certain claim of yours has been proven dead in the water, I don't know how the horse enters the picture.

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neil holmes
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Re: Another Olympus E-M1 and SONY a7 walkabout test, high ISO
In reply to Daniel Wee, 10 months ago

Thanks for that.   very interesting.

While the difference is not as big as FF vs M4/3 would indicate, I do think that I would stick to the A7 in low light most of the time.

The Oly to me is an excellent camera for many things while the A7 does fewer things but what it does well it does better....just

I will see if I can do some comparison shots between my A7 and FD 24 1.4L (at 5.6) and my GX7 with 12mm f2 (at 2.8) later.

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Lab D
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Re: He'll never learn
In reply to blue_skies, 10 months ago

blue_skies wrote:

Lab D wrote:

The service that DxO provides for sensors is that you can look at the graphs and determine how a sensor will perform at a given ISO. Since some systems have slower zoom lenses, you can also compare while adjusting for the differences between lens apertures by look at different ISOs.

So, when you look at the A7/A7R and the E-M1 for ISO1600, you can easily see the difference in DR is about 1/2 stop. The "overall" score is obviously not helpful here and if anything is wrong for that situation. Now if you want to compare the cameras with their fastest available native zooms, you can read the E-M1 line at ISO800 and compare to the A7 at ISO1600. Again this is far more accurate than trying to use those overall scores.

It frustrates me when newbies only look at the overall DxO scores and don’t understand what they mean. What is worse is when they don’t look at the actual findings which better represent reality and all the specific situations you may run into.

Your frustration is loud and clear.

Also, many of your posts frustrate others, but I guess that that does not count....

This is because we present facts tht conflict with you desired outcome (dream).  Of course you get frustrated.

We know that some here don’t want to know the truth and have other motives. :

)

btw, you are right. When people mention "equivalence" they ar talking about using the same DoF. When you do that these days the smaller sensor wins for SNR and other measurements. As long as the smaller sensor can give you the shallow DoF you want, it will perform better than the larger one IMHO.

It is simply to hard to have a conversation with you, you constantly keep bringing up different points (facts) and changing topics (presenting actual facts).

Perfect example.  When we are comparing how 2 cameras will perform at various ISOs, rather than look at the measurements for those ISOs, you only want to use the overall scores which are meaningless in those situations.   Then when we are discussing the difference in apertures for 2 lenses so we can judge real world results, you want to ignore those differences because it conflicts with your desire outcome.

Here is the reality.  If we want to take a picture with an A7 and need the DOF of an F/5.6 lens and need to shoot at 1/60 of second and ISO3200 to expose the image properly, we will find that the E-M1 does a BETTER job with higher IQ (less noise more DR) because we can use F/2.8, 1/60 and ISO800 while achieving the same FoV and same DoF.

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blue_skies
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Re: He'll never learn
In reply to Lab D, 10 months ago

Lab D wrote:

blue_skies wrote:

Lab D wrote:

The service that DxO provides for sensors is that you can look at the graphs and determine how a sensor will perform at a given ISO. Since some systems have slower zoom lenses, you can also compare while adjusting for the differences between lens apertures by look at different ISOs.

So, when you look at the A7/A7R and the E-M1 for ISO1600, you can easily see the difference in DR is about 1/2 stop. The "overall" score is obviously not helpful here and if anything is wrong for that situation. Now if you want to compare the cameras with their fastest available native zooms, you can read the E-M1 line at ISO800 and compare to the A7 at ISO1600. Again this is far more accurate than trying to use those overall scores.

It frustrates me when newbies only look at the overall DxO scores and don’t understand what they mean. What is worse is when they don’t look at the actual findings which better represent reality and all the specific situations you may run into.

Your frustration is loud and clear.

Also, many of your posts frustrate others, but I guess that that does not count....

This is because we present facts tht conflict with you desired outcome (dream). Of course you get frustrated.

We know that some here don’t want to know the truth and have other motives. :

)

btw, you are right. When people mention "equivalence" they ar talking about using the same DoF. When you do that these days the smaller sensor wins for SNR and other measurements. As long as the smaller sensor can give you the shallow DoF you want, it will perform better than the larger one IMHO.

It is simply to hard to have a conversation with you, you constantly keep bringing up different points (facts) and changing topics (presenting actual facts).

Perfect example. When we are comparing how 2 cameras will perform at various ISOs, rather than look at the measurements for those ISOs, you only want to use the overall scores which are meaningless in those situations. Then when we are discussing the difference in apertures for 2 lenses so we can judge real world results, you want to ignore those differences because it conflicts with your desire outcome.

Here is the reality. If we want to take a picture with an A7 and need the DOF of an F/5.6 lens and need to shoot at 1/60 of second and ISO3200 to expose the image properly, we will find that the E-M1 does a BETTER job with higher IQ (less noise more DR) because we can use F/2.8, 1/60 and ISO800 while achieving the same FoV and same DoF.

And we have come full circle:

http://www.dpreview.com/forums/post/53008914

Thanks for the samples, they are very helpful.

I would remind everyone that Olympus has wider aperture lenses and IBIS too. This means if you use the Olympus 12-40mm F/2.8 as a walkabout lens, not only will you have a greater range and more uses (also a great close-up lens), but you will get 1 extra stop of light over the new Sony 24-70mm F/4 lens.

And if you are using primes, the FE primes don't have IS, so the IBIS will in some cases also give you a couple extra stops advantage.

For me it doesn't matter. There are no avaialbe long lenses fo rthe A7 and the focusing is still not good. For me the Sony is not even a consideration because it can't do what I want.

My point, that the f/4.0 on the A7 was a stop faster still holds, as you compare f/5.6 versus f/4.0.

Again, the A7 has a f/4.0 lens and the M1 has a f/2.8 lens. You can therefore not match DOF and reach equivalence with the A7. The A7 is one stop faster - shallower DOF with less noise.

So, per your text above, I think that you finally agree with me on this one.

As to the other discussions, f/2.8 is a slow lens (f/5.6 on FF). More typically (I use) are f/2.0 and f/1.4. They do not (really) have equivalences on m43, meaning that the two formats are best used differently (in terms of DOF/Noise/IQ).

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Henry

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blue_skies
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Re: Thanks for the truth!
In reply to Anders W, 10 months ago

Anders W wrote:

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Anders W wrote:

blue_skies wrote:

Lab D wrote:

blue_skies wrote:

Lab D wrote:

blue_skies wrote:

Lab D wrote:

skyglider wrote:

blue_skies wrote:

skyglider wrote:

blue_skies wrote:

How so: in equivalence terms, the Oly 12-40/f2.8 becomes 24-80/f5.6 versus the Sony 24-70/f4.0?

Hi Henry,

I understand how the Oly 12-40mm is equivalent to 24-80mm in 35mm terms because of the 2x crop factor of the micro 4/3 sensor. But AFAIK, the aperture remains the same.

IOW, if an Oly 12mm lens could be used on a full frame (35mm) sensor, only the center 1/4 of the sensor area would be illuminated which is equivalent to 1/2 the horizontal and vertical pixels. Thus the crop factor of 2x. But the aperture remains the same so the same amount of light is hitting that portion of the sensor by the F2.8 aperture. So the aperture does "not" become equivalent to a F5.6 aperture.

Is my understanding incorrect?

Thanks,
Sky

Hi Sky, no your understanding is correct.

In terms of ISO, aperture and shutter speed, the exposure is the SAME on the small and the larger sensor.

If you are after (fast) shutter speed, you only care about the lens speed, and your thinking is correct.

But in terms of noise, the larger sensor allows to operate at a much higher ISO level and produce the same amount of noise: in m43/FF this is a 4x ratio, or 2 stops. This means that eg. m43 at ISO 1,000 is as noise as FF at ISO 4,000.

So, if you want to produce comparable images, you would shoot the FF image with two stops slower aperture and at two stops higher ISO. This is equivalent exposure.

Ironically, the same metric applies to DOF - you roughly see about the same DOF in both images as well.

Thus, shooting the Oly at 12mm f/2.8, ISO 1,000 as 1/60th is equivalent to shooting the Sony at f/5.6, ISO 4,000 and 1/60th. Aside from the resolution, the two images will appear similar.

If you use the same exposure on both, you are comparing the FF at ISO 1,000 versus the Oly at ISO 1,000. The FF image will have a lot less noise, ie. be much cleaner, but the DOF will also be reduced. The images are not equivalent at that point.

On FF you can trade noise for DOF, assuming you have a fast lens. There is a 2 stop delta to play with.

In the example, using the Sony lens at f/4.0 implies that the ISO goes to 2,000. This is one stop below the equivalent values of f/5.6 and ISO 4,000, so, with more shallow DOF, you will have a less noisy image on the FF.

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Cheers,
Henry

Hi Henry,

I think I understand your point now. I wondered how many stops difference there was between a micro 4/3 sensor verses a full frame sensor. Now I know it's a 4x ratio or 2 stops difference.

That only applies for Depth of field. If you check the results from DxO tests, the difference is much less. A good example is dynamic range where the E-M1 is only about 1/2 stop different than the A7 for most of the ISO settings DxO tested.

Remember if you need F/2.8, 1/60th sec shutter speed, and ISO800 on the E-M1, you will need the SAME settings on an A7, a Nikon 1 and a Sony RX100. It would even be the same on your smartphone!

Again, exposure = exposure and equivalence = equivalence.

And you know in this case equivalance does not tell us the facts. Admit it, there is NOT a 2 stop difference for noise or dynamic range at almsot all the ISOs DxO tested.

Just admit the truth for once.

Henry showing the difference between sensors

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Cheers,
Henry

You are right with the DxO link. The difference is really negligible. There is not a 2 stop difference almost all of time here.

?????

Please go take ISO 6400 pictures with your EM1 then

You conveniently deleted that I stated that it is immaterial whether it is 2x, or 1.65x, or 1.5x stops.

Where did you state that? And of course it isn't immaterial. If it's less than two stops (as it certainly is), MFT has an advantage with regard to signal-noise performance for equivalent images (same DoF, same shutter speed, different exposure, different ISOs).

http://www.dpreview.com/forums/post/53010416

"If DxO points out that it is 1.65x stops or 1.5x stops, it does NOT CHANGE the general thoughts"

It certainly does. The facts are as follows:

1. With respect to exposure, that is, the amount of light falling on the sensor per area unit (e.g., per square millimeter), f/2.8 on MFT is equivalent to f/2.8 on FF.

2. With respect to the total amount of light falling on the sensor, DoF, and diffraction, f/2.8 on MFT is equivalent to f/5.6 on FF (assuming, with regard to DoF, that the AoV and the focus distance is the same).

3. The total amount of light falling on the sensor is not the only determinant of signal-noise performance. What additionally matters is the quantum efficiency and the read-noise performance. In these regards, smaller sensors tend to be more efficient than larger sensors, as illustrated, for example by the graph posted by Lab D. Consequently, the difference between the A7/A7R and the E-M1 with regard to signal-noise performance at the same exposure is less than two stops.

You consistently overlook point 3 in spite of the fact that it has repeatedly been pointed out to you for months.

Not at all Anders, you have elaborated on this in the past,

Nevertheless, you overlook it time and again.

and the difference, even per DxO, they rate the ISO performance for the cameras as EM1/A7/A7r as 757/2248/2746. Two stops would have been 3028. So we all agree?

Not quite. While these figures too show the difference to be less than two stops, they underestimate the actual advantage of the E-M1 for equivalent images. The DR curve posted by Lab D provides a better indication with regard to shadow noise, which in turn is the most apparent problem in high ISO shooting. What the curves indicate is that the E-M1 is about 1.5 stops ahead of the A7/A7R for equivalent images (DoF held constant) and about 0.5 EV behind at the same exposure (and different DoF).

Sure, MFT has a 'technical advantage' but the image is worse - my eyes don't deceive me - download Daniel's newly uploaded full-image side-by-side and see for yourself.

Your eyes may not deceive you but your brain certainly does. Daniel's images are not equivalent images (see definition above). Rather they are images shot at the same exposure, in which case the A7 can be expected to do better with regard to signal-noise performance (although less than two stops better) but at the expense of two stops less worth of DoF.

And this is my argument: users shoot alike Daniel, and this produces images that may or may not be equivalent

An argument for what? It is certainly not a relevant objection to the point Lab D and I were making.

- even in Daniel's case he tried to match FL, aperture and framing as best as he could. Yet the resulting images speak for themselves.

As a rule (his practice was not entirely consistent) he matched f-stop but as we know that does not give equal DoF. If he had chosen to shoot equivalent images, as he might well have done, the outcome with regard to signal-noise performance would have been different.

It is immaterial, imho, as I would not use a smaller sensor camera at higher ISO. Why not? Because the image quality degrades too much. I would rather use longer exposure and lower ISO, if possible.

When you are in a position to freely increase the length of the exposure (because the scene is static), you are also free to bracket exposure and merge/align multiple images. This makes sensor performance a moot point.

When you are not in a position to do so, MFT has the advantage with regard to signal-noise performance for equivalent images.

See the image above, sure, it can be improved upon, but as Daniel said "the way a user would do it". Clearly the images are not similar in IQ, neither at ISO 100 nor at ISO 3200.

Again, the images above are not equivalent.

They are not, and I expected the high ISO image to perform better on the larger sensor. Again, read noise and pixel noise are not the same, and the larger sensor has larger pixels.

I don't think anyone has different expections than you in that regard. If you give the larger sensor the same exposure, it will have an advantage with regard to signal-noise performance at the expense of DoF.

But the low ISO image surprised me, I would have expected the ISO 100 images to be much closer to each other in IQ than they in fact are.

This is a scene with extreme dynamic range. Here's how to do such a scene better from a signal-noise point of view than either an E-M1 or an A7/A7R can manage in a single shot (nine shots with the E-M5 and the 12/2 at f/4, with shutter speeds varying from 1/8 s to 30 s, base ISO, merged and aligned in PP).

And we have had this discussion so many times already. Why the nitpicking?

Because you are not admitting the truth.

What truth?

The truth contained in my point 3 above.

Which shows that the ratio is not proportional to sensor size. It still confirms that larger sensors perform better.

No it doesn't. Rather it confirms that the smaller sensors do better from a signal-noise point of view when DoF is held constant. In order to do better from a signal-noise point of view, the larger sensor has to sacrifice DoF.

Let me explain: per your point, an 'equivalent' exposure on the smaller sensor would be of higher IQ. But the larger sensor allows more noise/DOF trade-off which results in a higher IQ image (but non-equivalent), at the cost of shallow DOF (which may or may not matter).

As far as I am concerned, DoF is just as much a part of IQ as is signal-noise performance.

I thank Daniel for uploading the images - they speak for themselves.

Only if you know how to interpret them correctly and you just showed you didn't.

Which image would you hang on the wall then? Perhaps not equivalent, but one camera is cleanly cleaner.

And the other clearly has better DoF. In most of the sample images, the DoF provided by the A7 is too shallow based on my preferences.

Technical slides do not tell this story, and in the analysis we get lost in sensor efficiency, not image IQ.

"Technical slides" (I'd call them diagrams) do tell the story as long as they reflect relevant and accurate measurements (as they do in this case). And sensor efficiency has implications for image quality as indicated by my point 3 above.

Yes, and you repeat this as often as you can. But to my point - show side-by-side images, let them speak. We have side-by-side images here to point at, and I would definitely pick the larger sensor camera.

I have no objections to looking at images side by side. But those we got here do not show all the relevant comparisons and my choice between those we can see would be different than yours. As I said, I find the DoF of the A7 images too shallow in most cases (1st, 2nd, 4th, and 5th pair). Pair 3 is a failure (wrong focus on the MFT image) and for pair 6, DoF is irrelevant.

Change the venue and shoot people walking at low ISO, I would expect the smaller sensor camera to pull ahead.

On what grounds do you think so?

Like I said, both cameras have pros and cons, but low light & high ISO (and shallow DOF) are not the smaller sensor's strong points.

The point here is rather that the smaller sensor is ahead in low light/high ISO whenever DoF is in short supply.

Lower the ISO, and both cameras are great. They both have their pros and cons.

They both have their pros and cons, but it is important to be factually correct about what those pros and cons are.

See my comments here: http://www.dpreview.com/forums/post/53009228

Pros and cons are subject to an individual bias.

The facts are objective, the evaluation of those facts is not.

Then show us how to shoot the M1? Obviously, users don't know how to.

What specifically makes you think they don't?

I like the image that you included. But I am not that fast in rejecting an image because of shallow DOF - there are (lots of) times when it works, but not always.

As to this debate - 32 posts and counting merely because I (dared) compared the 4x sensor difference to roughly 2 stops?

It wouldn't have had to be 32 posts if you had recognized right away that what you said in the post to which I link below was in some important regards wrong:

http://www.dpreview.com/forums/post/53009777

Even better would have been if you had spelled out the actual truth from the beginning. I hope that you will eventually learn to do that.

Lol, instead of 2x I will use 1.5x for A7 and 1.8x for A7r.

So, at equivalency, the M1 will be slightly better? But the A7/r do allow trading DOF and noise.

And perhaps also because I dared looking at actual images, rather than the theoretical perfect ones?

Certainly not. I have nothing against looking at images. Both diagrams of measurements and actual images are useful when it comes to understanding things like those we are discussing here.

The discussion was a side tangent. Shooting the M1 at f/2.8 and the Sony at f/4.0, as suggested by Lab D is not equivalent, and I rebutted to his statement.

The OP was not even using such lenses - he was comparing fast primes. The OP also could not reach equivalence - the f/1.4 on EM1 versus f/1.8 on the Sony gives the Sony, again, room to trade DOF and noise.

Ok, I get it, you guys are relentless, and will never stop.

We are only as relentless as you force us to be.

Lol, that is because you take every statement and keep adding and rebutting.

My point: the larger sensor produces less noise with shallow DOF still stands.

Your point, with a 1.5x ratio versus 2.0 the M1 pulls ahead at equivalency also stands.

My 2nd point: look at some of the images, shallow DOF does get into play, and now sensor size matters.

Yes, I understand that you do not like shallow(er) DOF, well, I do. I like less noisy images.

Can we call this a dead horse now?

While a certain claim of yours has been proven dead in the water, I don't know how the horse enters the picture.

I have no idea how you got here: I repeat, and have repeated, numerous times and have refined and agreed with you guys.

It is very clear that (me) stating that a 4x sensor difference yields a roughly 2x stop difference is a VERY BIG DEAL. Well, the A7 has 1.5x stop and the A7r has 1.8x difference (if I calculated correctly).

Again, for equivalency (which I see as deep DOF images) the M1 may have the advantage - and so does the 1" sensor of the RX10 or RX100 (over the M1).

But, one more time: shooting below f/2.0 (or even f/2.8) on FF gets a bit unwieldy on m43 in terms of equivalency. If shallow DOF is an option, the FF becomes the preferred format. And at many a times, shallow DOF may not only be an option, but actually be desired.

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Henry

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Lab D
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Re: Thanks for the truth!
In reply to blue_skies, 10 months ago

blue_skies wrote:

Henry showing the difference between sensors

It is very clear that (me) stating that a 4x sensor difference yields a roughly 2x stop difference is a VERY BIG DEAL. Well, the A7 has 1.5x stop and the A7r has 1.8x difference (if I calculated correctly).

Could you show us where on the DxO graph between ISO100 and ISO6400 where the differences are 1.5 and 1.8 stops?  Just answer with the specific ISOs please.

I see about 1/2 at almost every ISO, but not anywhere near the 1.5 you keep dreaming of.

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Joel Stern
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Re: Another Olympus E-M1 and SONY a7 walkabout test, high ISO
In reply to Daniel Wee, 10 months ago

Thank you Daniel. To my amateur eye they both look very close with nicer Bokeh going to the Olympus. I bet the only time you will tell any difference will be when printing large....

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Re: Thanks for the truth!
In reply to blue_skies, 10 months ago

blue_skies wrote:

Anders W wrote:

Henry showing the difference between sensors

Lol, instead of 2x I will use 1.5x for A7 and 1.8x for A7r. So, at equivalency, the M1 will be slightly better?

Sorry but apparently you still didn't get it. As you can see from the diagram above, the E-M1 is about 1.5 EV ahead for equivalent images and about 0.5 EV behind for non-equivalent ones (same exposure, different DoF).

Hopefully, you also remember this part of our exchange:

Henry said: and the difference, even per DxO, they rate the ISO performance for the cameras as EM1/A7/A7r as 757/2248/2746. Two stops would have been 3028. So we all agree?

Anders W said: Not quite. While these figures too show the difference to be less than two stops, they underestimate the actual advantage of the E-M1 for equivalent images. The DR curve posted by Lab D provides a better indication with regard to shadow noise, which in turn is the most apparent problem in high ISO shooting. What the curves indicate is that the E-M1 is about 1.5 stops ahead of the A7/A7R for equivalent images (DoF held constant) and about 0.5 EV behind at the same exposure (and different DoF).

But the A7/r do allow trading DOF and noise.

So of course does the E-M1. It's just a matter of how far you want to take that trade. If, as a rule, you don't want more shallow DoF than you can get with a fast MFT prime, you will lose rather than gain signal-noise performance by choosing the A7/r.

We are only as relentless as you force us to be.

Lol, that is because you take every statement and keep adding and rebutting.

No that's because you persist, in the most arrogant manner (just look at your first reply to Lab D here) in repeating your factual errors.

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skyglider
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So what's the consenses between the E-M1 vs A7 regarding noise in stops?
In reply to Daniel Wee, 10 months ago

There's been a lot of data posted in this thread. But I'm still left wondering. Which camera system will produce better looking images with less noise in low light situations like an indoor wedding at a dimly lit church (no flash allowed)?

  1. Micro 4/3:  OMD E-M1 with the 12-40mm, F2.8 Pro lens?
  2. Full Frame: Alpha 7 with the kit 24-70mm F3.5 - F5.6 OSS lens?

Sky

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blue_skies
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Re: Thanks for the truth!
In reply to Anders W, 10 months ago

Anders W wrote:

blue_skies wrote:

Anders W wrote:

Henry showing the difference between sensors

Lol, instead of 2x I will use 1.5x for A7 and 1.8x for A7r. So, at equivalency, the M1 will be slightly better?

Sorry but apparently you still didn't get it. As you can see from the diagram above, the E-M1 is about 1.5 EV ahead for equivalent images and about 0.5 EV behind for non-equivalent ones (same exposure, different DoF).

Hopefully, you also remember this part of our exchange:

Henry said: and the difference, even per DxO, they rate the ISO performance for the cameras as EM1/A7/A7r as 757/2248/2746. Two stops would have been 3028. So we all agree?

Anders W said: Not quite. While these figures too show the difference to be less than two stops, they underestimate the actual advantage of the E-M1 for equivalent images. The DR curve posted by Lab D provides a better indication with regard to shadow noise, which in turn is the most apparent problem in high ISO shooting. What the curves indicate is that the E-M1 is about 1.5 stops ahead of the A7/A7R for equivalent images (DoF held constant) and about 0.5 EV behind at the same exposure (and different DoF).

But the A7/r do allow trading DOF and noise.

So of course does the E-M1. It's just a matter of how far you want to take that trade. If, as a rule, you don't want more shallow DoF than you can get with a fast MFT prime, you will lose rather than gain signal-noise performance by choosing the A7/r.

We are only as relentless as you force us to be.

Lol, that is because you take every statement and keep adding and rebutting.

No that's because you persist, in the most arrogant manner (just look at your first reply to Lab D here) in repeating your factual errors.

Lab D has a history of being very arrogant to a number of specific people, including me, hence the tone of my response. Sorry if that hit a nerve, but I am merely responding to him.

As to the graph that you keep posting, I think that is a very specific interpretation. It is an 8Mp print measured graph, not the actual sensor/image resolution, and there have been lots of debates on this.

Please read http://www.luminous-landscape.com/essays/dxomark_sensor_for_benchmarking_cameras2.shtml and correct or not, it does bring enough questions to the table to try to understand what DxOMark is measuring.

I think that DxOMark should be applauded for what they did, and - to my very simple naive interpretation - they put out an ISO level on their score page http://www.dxomark.com/Cameras/Compare/Side-by-side/Sony-A7-versus-Sony-A7R-versus-Olympus-OM-D-E-M1___916_917_909 which I do find relevant for the various sensor formats.

Each camera model begins to exhibit visible noise at their rated ISO level - I can attest to that from my own usage, as well as the various reports that are out there (dpreview).

DxOMark also reports an overall sensor score, and lens+camera combinations. You may agree or disagree with their metrics, but they do help interpreting the data.

DxOMark shows, per the ll article, that larger sensors do not maintain the efficiency of smaller sensors, so "there may be some headroom left for the engineers/manufacturers". And it highlights your claims that smaller sensor perform better, in comparison.

But I agree with the DxOMark interpretation: larger sensor outperform smaller sensor. At least in terms of noise. They have hang their ratings on this for a long time, and many do agree to their way of classifying cameras (and sensors).

How much, and by which difference - that is a long debate going on here - technical or not, when I see images side by side, I see less resolution and more noise on smaller sensor cameras. Perhaps the images are not matched in equivalency, and your reasoning holds up, but I would not shoot a small sensor camera at high ISO while I would not be afraid to shoot a larger sensor camera at high ISO.

Theory or not, practicality prevails. I am happy with my low light/low noise results. Perhaps your equivalency analysis holds merit, I am trading shallow DOF when lights are low (indoors), or I use the flash to get a different effect.

With a smaller format sensor, I already feel like being in a corner - hence the migration to larger sensors.

And sorry, per all the discussions, I do not see m43 matching FF for low light applications.

You may say that DOF gets too shallow, I would say that DOF gets too deep.

Can we agree to disagree?

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Henry

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Lab D
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Re: So what's the consenses between the E-M1 vs A7 regarding noise in stops?
In reply to skyglider, 10 months ago

skyglider wrote:

There's been a lot of data posted in this thread. But I'm still left wondering. Which camera system will produce better looking images with less noise in low light situations like an indoor wedding at a dimly lit church (no flash allowed)?

  1. Micro 4/3: OMD E-M1 with the 12-40mm, F2.8 Pro lens?
  2. Full Frame: Alpha 7 with the kit 24-70mm F3.5 - F5.6 OSS lens?

Sky

Sony has a 28-70 f3.5-5.6 lens and an expensive 24-70 f4 lens.

The 28-70 is a poor kit lens. The other is much better.

The Olympus is a stop faster, has a wider range and makes a great close up lens.

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