Crop Factor, Low Light and Aperture with m4/3 lenses?

Started Jun 15, 2014 | Discussions
Anders W Forum Pro • Posts: 21,468
Re: Very simple:

Just another Canon shooter wrote:

Anders W wrote:

FF has the same noise for equivalent images only if the sensors are equally efficient. But as a rule they are not. Smaller sensors tend to be more efficient than larger. See here:

http://www.dpreview.com/forums/post/53189207

Not true. QE of newer sensors is about 53%, see sensorgen, from m43 to APS-C to FF.

Sensorgen doesn't have data for many of the sensors in my sample and are based on fitting curves to numbers that results from previous curve fitting. Further, QE is an indirect measure that doesn't take certain facts into account (e.g., fixed pattern noise and read noise). My more direct measures are not subject to any of these problems.

What you are talking about is read noise at higher ISOs (affecting mostly the deep shadows), where the current m43 sensors are better by about a stop.

Please read the post I linked to (including references to other posts). I am not talking about read noise at higher ISOs only. I used four different indicators, two for lower and two for higher ISO, and two indexing DR and the other two indexing max SNR.

But for that, you need, say, f/1.4 vs. f/2.8, and the sensor would not be able to register at least 1/2 stop of that light, you get a noticeably lower resolution, etc.

I would need f/1.4 vs f/2.8 only if the sensors were equally efficient. My point is that they are not.

As to the rest, please elaborate/substantiate what you have in mind.

What FF can do is to take non-equivalent images, as simple as that.

Yes. Nobody disputes that. What I disputed was your claim that it can take equivalent images just as well as smaller sensors as far as noise is concerned. Since smaller sensors tend to be more efficient than larger, that's not the case.

When you must take equivalent images, there is still a resolution advantage,

See my request for elaboration/substantiation above.

but there is no IS (sometimes) disadvantage and the lower DR you mentioned, with the current sensors.

Yes. DR is part of the efficiency of the sensor.

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Just another Canon shooter
Just another Canon shooter Veteran Member • Posts: 4,691
Re: Very simple:

Anders W wrote:

Just another Canon shooter wrote:

Anders W wrote:

FF has the same noise for equivalent images only if the sensors are equally efficient. But as a rule they are not. Smaller sensors tend to be more efficient than larger. See here:

http://www.dpreview.com/forums/post/53189207

Not true. QE of newer sensors is about 53%, see sensorgen, from m43 to APS-C to FF.

Sensorgen doesn't have data for many of the sensors in my sample and are based on fitting curves to numbers that results from previous curve fitting.

It does, for the most relevant bodies.

Further, QE is an indirect measure

It is what it is, it has a clear definition.

that doesn't take certain facts into account (e.g., fixed pattern noise and read noise).

It should not. Read noise is a different parameter.

My more direct measures are not subject to any of these problems.

I did not read your posts and I do not have to. You are trying to give your own definitions, then to compute the "efficiency", and then what - to compute the noise? But DXO measured the noise. What is the point of your exercise then?

DXO measured 2 stop difference at 18% gray. This is the theoretical factor, so we have the same QE. This is based on the theoretical model here, and also somewhere on the DXO site. So, same QE, as simple as that. We do not really know what it is, but we know they are the same.

About DR - DXO measured that as well. Difference about 1.2 stops or so, short of 2 stops. Since they define ISO as the saturation level, that tells you what the read noise is. Pattern noise is not a problem with newer FF bodies at high ISO - only with Canons at low ISO but m43 cannot even capture so much light, so what is the point of discussing it.

But for that, you need, say, f/1.4 vs. f/2.8, and the sensor would not be able to register at least 1/2 stop of that light, you get a noticeably lower resolution, etc.

I would need f/1.4 vs f/2.8 only if the sensors were equally efficient. My point is that they are not.

Of course, by "for that", I meant to realize the hypothetical "efficiency advantage". Then you must be at equivalent apertures.

What FF can do is to take non-equivalent images, as simple as that.

Yes. Nobody disputes that. What I disputed was your claim that it can take equivalent images just as well as smaller sensors as far as noise is concerned.

Noise and resolution are related, so higher resolution helps offset some part of the noise.

Since smaller sensors tend to be more efficient than larger, that's not the case.

Since they are not, it is not.

Yes. DR is part of the efficiency of the sensor.

It is not. You want to make it though.

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Just another Canon shooter
Just another Canon shooter Veteran Member • Posts: 4,691
Re: Very simple:

Ontario Gone wrote:

Just another Canon shooter wrote:

The best way to think about this is in equivalence terms. FF does not have a lower noise advantage (for equivalent images) - it has the same noise (but better resolution in general, which can offset some of that). You can trade in DOF for less noise with any system. What FF does better is that it has more latitude, with the common lenses, to get a shallower DOF, which means more total light and therefore less noise.

Hmm, i don't think this is right. Yes it's true that current FF have more pixels, but it doesn't have to be that way, it's just happenstance atm. If resolution was the same for a MFT vs FF, and if you shoot at equivalent settings, its all the same. Why? Diffraction. Diffraction causes diminishing returns with higher resolution, but it's based on aperture. With equivalence settings, aperture is equal, which means both are affected equally by diffraction, both have equal IQ numbers like ISO/DR/color, and both have the same pixel count.

Of course, I was talking about camera-lens system, not about a pixel count. At wider (equivalent) apertures, larger systems resolve noticeably more.

Since the OP mentioned APS-C - the m43 has the advantage of having more lenses designed for it, and IBIS. If I know that I will never go FF (well, I already did ), I would rather get an m43 system because of the better suited lens selection, IBIS, weight and size. The recent mirror-less Fuji, etc. are other interesting options.

EDIT: About the post above: "assume the same ISO..." - don't. There is no reason to assume that. Think about auto ISO, or even better, no ISO at all. You chose the aperture and the shutter speed; the ISO is a secondary thing.

You have to think about ISO, even if it's just base ISO. After all, it's not the number that matters, its the boosting. Whatever that amount is, it matters. If the manufacturer numbers bother you, make a chart, call it by "real" ISO numbers. Either way, it's a factor the needs to be equalized in terms of equivalence.

It does not. Choose the SS and the aperture and the SS, and the exposure is set. Then choose whatever ISO works with it. Unless you are blowing the highlights, 1 stop ISO difference will make minor changes to you image, especially with non-Canon cameras.

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Alan Lai Regular Member • Posts: 300
Re: You should have kept going...
1

Kevin Sutton wrote:

His explanation of ISO and sensor noise was VERY illuminating. I now understand...

Cheers Kevin

Sounds like something from Church on Sundays.

P.S. I watched this video. Illuminating? Definitely not.

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Anders W Forum Pro • Posts: 21,468
Re: Very simple:
3

Just another Canon shooter wrote:

Anders W wrote:

Just another Canon shooter wrote:

Anders W wrote:

FF has the same noise for equivalent images only if the sensors are equally efficient. But as a rule they are not. Smaller sensors tend to be more efficient than larger. See here:

http://www.dpreview.com/forums/post/53189207

Not true. QE of newer sensors is about 53%, see sensorgen, from m43 to APS-C to FF.

Sensorgen doesn't have data for many of the sensors in my sample and are based on fitting curves to numbers that results from previous curve fitting.

It does, for the most relevant bodies.

Why should we use partial data if we can use more complete data? And why should we use fitted data points if we can use real data points?

Further, QE is an indirect measure

It is what it is, it has a clear definition.

That does not help. My measures are just as clearly defined but closer to what we are interested in: Image quality.

that doesn't take certain facts into account (e.g., fixed pattern noise and read noise).

It should not. Read noise is a different parameter.

It is different from QE, yes. So what? What we are interested in is the signal-noise performance. Read noise is part of that.

My more direct measures are not subject to any of these problems.

I did not read your posts and I do not have to.

If you want to argue convincingly, I am afraid you have to.

You are trying to give your own definitions,

I use DxO measures.

then to compute the "efficiency",

Yes.

and then what - to compute the noise?

No. What makes you think that?

But DXO measured the noise. What is the point of your exercise then?

I make no attempt to measure noise as a stand-alone quantity. Like DxO, I measure what we are interested in from an image-quality point of view: Signal-noise performance.

DXO measured 2 stop difference at 18% gray. This is the theoretical factor, so we have the same QE.

See above regarding QE.

This is based on the theoretical model here, and also somewhere on the DXO site. So, same QE, as simple as that. We do not really know what it is, but we know they are the same.

The efficiency with regard to signal-noise performance, which is what we are interested in for the purpose of comparing image quality is not the same.

About DR - DXO measured that as well. Difference about 1.2 stops or so, short of 2 stops.

Yes, less than two stops on average and sometimes even negative. Since DR is a good measure of signal-noise performance in dark tones/areas and since that is more perceptually important than signal-noise performance in brighter tones/areas, the difference in image quality between FF and MFT at the same ISO is significantly less than two stops.

Since they define ISO as the saturation level, that tells you what the read noise is.

Yes, you can compute the read noise if you want. So what? What I study is signal-noise performance.

Pattern noise is not a problem with newer FF bodies at high ISO

So what?

- only with Canons at low ISO but m43 cannot even capture so much light, so what is the point of discussing it.

Because it affects the signal-noise performance in which we are interested.

But for that, you need, say, f/1.4 vs. f/2.8, and the sensor would not be able to register at least 1/2 stop of that light, you get a noticeably lower resolution, etc.

I would need f/1.4 vs f/2.8 only if the sensors were equally efficient. My point is that they are not.

Of course, by "for that", I meant to realize the hypothetical "efficiency advantage". Then you must be at equivalent apertures.

No. The efficiency advantage of smaller sensors means that they can go equal with larger sensors at less than equivalent apertures.

What FF can do is to take non-equivalent images, as simple as that.

Yes. Nobody disputes that. What I disputed was your claim that it can take equivalent images just as well as smaller sensors as far as noise is concerned.

Noise and resolution are related, so higher resolution helps offset some part of the noise.

The comparisons I perform are with resolution held constant (DxO "print mode") so any differences in sensor pixel count are already properly accounted for.

Since smaller sensors tend to be more efficient than larger, that's not the case.

Since they are not, it is not.

I have undertaken a systematic analysis showing that smaller sensors tend to be more efficient than larger, no matter whether we consider lower or higher ISOs and no matter whether we consider the brightest or the darkest tones. You haven't shown anything.

Just asserting things doesn't help. Where's your data? Where's your statistical analysis? Come back when you have something to report. Then we can talk again.

Yes. DR is part of the efficiency of the sensor.

It is not. You want to make it though.

You are confusing quantum efficiency with sensor efficiency more generally. QE is one measure of sensor efficiency. It is inferior to those I use in being a less comprehensive and less direct measure of signal-noise performance, which is what we are actually interested for the purpose of comparing image quality.

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Sergey_Green
Sergey_Green Forum Pro • Posts: 11,997
Oh no, not again please ..

Anders W wrote:

Sergey_Green wrote:

Very nicely summed up, I would only add few words about the low noise, if I may. Most of the scenes in the world are middle-gray (or reflect about 18% of light),

On the contrary, most scenes are not middle gray. Rather, most scenes include tones that range all the way from very dark to very bright.

and that is where the larger formats are often ahead regardless of what sensors they have.

On the contrary, smaller sensors are more efficent than larger and therefore tend to do better for equivalent photos like those described by Great Bustard above. This is true for middle gray but even more so for darker tones, which have the poorest signal-noise ratio and where noise is therefore most visible.

The dark shadows, on the other hand, is usually not where the least most important information in the images is,

On the contrary, both the bright and dark tones of an image tend to be important. And the dark tones do not need to be in the shadows. A black cat remains black even if lit.

and can be cleaned without ill-effects to the rest of the captured scene. That is, if anyone is bothered by it.

On the contrary, the dark tones cannot as a rule be "cleaned" without ill effects. Consider for example the hair of the girl in the example to which I link below.

http://www.dpreview.com/reviews/image-comparison?attr18=lowlight&attr13_0=oly_em1&attr13_1=sony_a7&attr13_2=sony_a7r&attr13_3=nikon_d800&attr15_0=raw&attr15_1=raw&attr15_2=raw&attr15_3=raw&attr16_0=3200&attr16_1=12800&attr16_2=12800&attr16_3=12800&normalization=print&widget=1&x=0.8342357734262059&y=0.2753099540100277

I think that is why you are so un-accomplished as a photographer, as obvious simply eludes you.

Let's start with this example you linked, and why it does not show what potential differences (between the cameras) there are. First, if the images are to be judged by this tone alone (very unlikely, unless you done something wrong from the start with it) there is not much difference between them. And if these blotches are offending, they all need to be cleaned up in one way or the other.

Secondly, (now you need to think as a photographer, just pretend you are one) every good image will have some central point in it, where you want your viewer to look at first. Do you remember what I said above? - It is mid-Gray. That is how we see what is in the light, and that is how the cameras are designed to meter, unless you over-write it to fit your specific as you see it needs. You meter on the dark, it becomes gray. You meter on highlights, they become gray. That is just the way it is. Regardless how dim the light may appear, if you meter correctly, the most important parts of your image(s) will inevitably become gray. As the series of images in this link demonstrate,

http://acwilli.smugmug.com/Other/Jakes-B-Ball-Jan-2014-EM1-35/

If it is not so obvious, let us look at few others. Camera phones are not known to prodice clean images (regardless of ISO), especially when pushed outside their comfort zones, but should we even care. Here's where noise was cleaned up, and only what matters is left intact (would you even know about it?),

It would have been very different had the image had noise in the areas where it matters the most.

Here is another one, taken rather early, and when the sun just only started showing up from over the mountains. Again, should the noise in the deepest of the shadows ever bother anyone, it is easily removed with no ill-effects to the image.

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- sergey

Sergey_Green
Sergey_Green Forum Pro • Posts: 11,997
If, only if ..

Anders W wrote:

FF has the same noise for equivalent images only if the sensors are equally efficient. But as a rule they are not. Smaller sensors tend to be more efficient than larger. See here:

If by efficient you mean the difference from the brightest to the darkest, but not what is in between.

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bobn2
bobn2 Forum Pro • Posts: 62,477
Re: Very simple:
2

Anders W wrote:

Just another Canon shooter wrote:

Anders W wrote:

Just another Canon shooter wrote:

Anders W wrote:

FF has the same noise for equivalent images only if the sensors are equally efficient. But as a rule they are not. Smaller sensors tend to be more efficient than larger. See here:

http://www.dpreview.com/forums/post/53189207

Not true. QE of newer sensors is about 53%, see sensorgen, from m43 to APS-C to FF.

Sensorgen doesn't have data for many of the sensors in my sample and are based on fitting curves to numbers that results from previous curve fitting.

It does, for the most relevant bodies.

Why should we use partial data if we can use more complete data? And why should we use fitted data points if we can use real data points?

Anders, if you have good data for a full range of cameras, why not publish it so we can all use it? Then the sensorgen data with its acknowledged faults would be redundant. As it is, your 'real data points' seem to be derived from exactly the same data and your method involves 'interpolation' - so the meaning or the word 'real' here is not maybe what most of us would think of as 'real'.

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Bob

tokumeino Senior Member • Posts: 2,683
Re: Nice summary but the supplement needs improvement

You forgot the Handevision Ibelux 40/0.85 ? Shame on you !

Sorry not to know extensively the M43 lineup. In fact I was mainly thinking of native AF lenses. Because if you come to manual ones, then you'll find much faster than f/1.8 FF lenses as well. I was actually thinking of lenses like the Pana 25/1.4 which is 1 stop behind a Sony FE 55/1.8.

But don't misunderstand me : I totally agree with you and I thnink that the advantages of large sensors are often overestimated. Many people compare at equal ISO, which does not make sense from a composition perspective.

Personally, I don't need "extreme" aperture and what M43 has to offer is more than enough to my needs. I can understand that people may have more specific needs and I don't blame them going to expensive and bulky FF, but I'm afraid that many could actually live with smaller sensors.

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tokumeino Senior Member • Posts: 2,683
Re: Very simple:

It become less and less "Very simple" Hard for me to follow.

Intuitively, I'm considering that, if you can produce sensors with a particular efficiency (/mm2) for M43, then you just have to make it bigger and you'll have the same efficiency for FF. Aren't FF manufacturers aware of the technology used for smaller sensors ? Of course, this is only intuition and I don't know of quantums, and can obviously go wrong.

This is in fact a interresting debate and if you could avoid to answer to each other point by point, it could be more readable and interresting. As it, I'm afraid it come to an argue, instead.

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Sergey_Green
Sergey_Green Forum Pro • Posts: 11,997
Handevision Ibelux ?

tokumeino wrote:

You forgot the Handevision Ibelux 40/0.85 ? Shame on you !

Sorry not to know extensively the M43 lineup. In fact I was mainly thinking of native AF lenses. Because if you come to manual ones, then you'll find much faster than f/1.8 FF lenses as well.

I think I am missing your point here. What is much faster than f/1.8 FF lenses?

I was actually thinking of lenses like the Pana 25/1.4 which is 1 stop behind a Sony FE 55/1.8.

Yes, it is 50/2.8 equivalent. An Ok to have, but nothing to give you an edge when it comes to DoF and light. And stopped down to f/2.8 fast FF lenses do usually produce better results, than a wide open on a smaller formats equivalents.

..

Personally, I don't need "extreme" aperture and what M43 has to offer is more than enough to my needs. I can understand that people may have more specific needs and I don't blame them going to expensive and bulky FF, but I'm afraid that many could actually live with smaller sensors.

Very true.

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Sergey_Green
Sergey_Green Forum Pro • Posts: 11,997
I think they are quite aware of it ..

tokumeino wrote:

It become less and less "Very simple" Hard for me to follow.

Intuitively, I'm considering that, if you can produce sensors with a particular efficiency (/mm2) for M43, then you just have to make it bigger and you'll have the same efficiency for FF. Aren't FF manufacturers aware of the technology used for smaller sensors ? Of course, this is only intuition and I don't know of quantums, and can obviously go wrong.

It is very often that new technologies are often introduced in compacts, way befor it becomes common on larger and FF formats. Sensor is not the only area where we have seen these innovations.

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- sergey

Truthiness Regular Member • Posts: 122
Re: Handevision Ibelux ?
1

Sergey_Green wrote:

tokumeino wrote:

I was actually thinking of lenses like the Pana 25/1.4 which is 1 stop behind a Sony FE 55/1.8.

Yes, it is 50/2.8 equivalent. An Ok to have, but nothing to give you an edge when it comes to DoF and light. And stopped down to f/2.8 fast FF lenses do usually produce better results, than a wide open on a smaller formats equivalents.

Additionally there is one inherit advantage larger formats have over smaller ones: enlargement factor. A large format image needs to be enlarged less than a medium format image, which needs to be enlarged less than FF image which needs to be enlarged less than APS-C image which needs to be enlarged less than m4/3 image which needs to be enlarged less than cell phone image and when less enlargement is needed, the lens is stressed less, thus the lens can be of lesser quality to achieve the same image quality.

texinwien Veteran Member • Posts: 3,326
Re: Handevision Ibelux ?
2

Truthiness wrote:

Sergey_Green wrote:

tokumeino wrote:

I was actually thinking of lenses like the Pana 25/1.4 which is 1 stop behind a Sony FE 55/1.8.

Yes, it is 50/2.8 equivalent. An Ok to have, but nothing to give you an edge when it comes to DoF and light. And stopped down to f/2.8 fast FF lenses do usually produce better results, than a wide open on a smaller formats equivalents.

Additionally there is one inherit advantage larger formats have over smaller ones: enlargement factor. A large format image needs to be enlarged less than a medium format image, which needs to be enlarged less than FF image which needs to be enlarged less than APS-C image which needs to be enlarged less than m4/3 image which needs to be enlarged less than cell phone image

This inherent factor is taken into account by switching from "Screen" to "Print" when viewing DXO's measurement graphs.

and when less enlargement is needed, the lens is stressed less,

What does "the lens is stressed less" mean? Is that accepted optics terminology? Do you have some links to authoritative sources that talk about this in more detail?

thus the lens can be of lesser quality to achieve the same image quality.

Lesser quality in what respect?

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Sergey_Green
Sergey_Green Forum Pro • Posts: 11,997
What he says ..
2

texinwien wrote:

What does "the lens is stressed less" mean? Is that accepted optics terminology? Do you have some links to authoritative sources that talk about this in more detail?

I think he means that to record the same amount of detail with the same number of pixels the lens that is in front of the smaller pixels must be resolving better, than the lens that is in front of the larger pixels. That is the smaller pixels on a smaller area with "stress" the lens more, than the larger pixels on the larger area.

thus the lens can be of lesser quality to achieve the same image quality.

Lesser quality in what respect?

As stated above.

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photohounds
photohounds Senior Member • Posts: 1,154
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

baxters wrote:

The crop factor is 2. That is why there is an Olympus 25mm f1.8 and a Panasonic 25mm f1.4. Both correspond to a 50mm lens on film. For exposure, the aperture is unchanged by crop factor. Both of these lenses will act like your 50mm f1.7 lens for focal length and exposure.

Depth of field (DOF) calculations do require you to multiply the aperture by 2. So if you like to calculate where a lens will start to go out of focus for blurred backgrounds, you will get less DOF in theory. In practice, you could show this in a lab. Out on the street, you could probably shoot someone with your 50 f1.7 on film or the 25mm f1.8 on an EM10 and both backgrounds will look the same because they are both far enough away.

The light sensitivity of digital cameras is far better than film. Any low light shooting you did with your 50mm f1.7 on film will be easily matched by the two above lenses on the EM10.

By the way, you can use your film lenses on the EM10.

Agree .. and ..
.
More for the OP .. The fast primes do the job nicely and produce SALEABLE work, unless you prefer exaggerated OOF effects like disappearing ears and other gimmicks.
Unlike some "legendary lenses" they are sharp wide open too (yes I'm looking at you .. soft 85/1.2) .
.
The 75 ... the 45 ... the 17 ... the 12 ... the 12-40 PRO etc, etc.
.
Oh . .
In low light (I could hardly see..) they perform well, too.
and trounced the tripod-bound CaNikon co-shooters.

.
Wanna go further?
That 42.5mm/1.2 Panasonic is a stellar performer if you actually DO need less DOF (beyond for pub bragging).
.
Someone is even making an f 0.85 42 or 45mm!
.
Another poster remarked on the maturity of the system comna=ret to similar cameras, I agree, it is very well developed already.
.
"Crop" is not really the right word, as the lenses and cameras are DESIGNED for this image size - that's why the primes deliver performance - from wide open.

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Well designed gear performs better for longer than well marketed gear.
Odd that people complain a lens is not sharp enough,
and then proceed to make pics where 95% is OOF ..
General Pics:
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Oly and other .. Gear test samples - even RB-67!:
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How DO OMDs cope with dim-light action and smoke?
http://photohounds.smugmug.com/Performing-arts

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Sergey_Green
Sergey_Green Forum Pro • Posts: 11,997
Why "exagerated"?
1

photohounds wrote:

.
More for the OP .. The fast primes do the job nicely and produce SALEABLE work, unless you prefer exaggerated OOF effects like disappearing ears and other gimmicks.

It depends on the distance you shoot from. On the other hand, you can do "gimmicks" with camera phone if you come close enough, don't you think?

Unlike some "legendary lenses" they are sharp wide open too (yes I'm looking at you .. soft 85/1.2) .

I can name several "legendary lenses" that are very sharp wide open, even today. For example (quite a story) Nikon 180/2.8 , or Nikon 135/2 DC , or Nikon 200/4 macro , ... and so on.

Why would you think they are not sharp, or not sharp enough when wide open?

.
The 75 ... the 45 ... the 17 ... the 12 ... the 12-40 PRO etc, etc.
.
Oh . .
In low light (I could hardly see..) they perform well, too.
and trounced the tripod-bound CaNikon co-shooters.

Certain type of photography does require tripods. This is Olympus user for example, nothing short of amazing in my book,

http://www.flickr.com/photos/32362657@N00/

.
Wanna go further?
That 42.5mm/1.2 Panasonic is a stellar performer if you actually DO need less DOF (beyond for pub bragging).

95/2.4 equivalent lens that is priced at €1509 here in Central Europe, you call it a bargain? I don't know about that one.

Someone is even making an f 0.85 42 or 45mm!

Manual lenses that are very expensive and only f/2 equivalent.

.
Another poster remarked on the maturity of the system comna=ret to similar cameras, I agree, it is very well developed already.
.
"Crop" is not really the right word, as the lenses and cameras are DESIGNED for this image size - that's why the primes deliver performance - from wide open.

Crop refers to the image size, not how the cameras and lenses are designed.

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- sergey

Just another Canon shooter
Just another Canon shooter Veteran Member • Posts: 4,691
Re: Very simple:
1

Anders W wrote:

So you are using the DXO data to compute some "efficiency factor" that you define yourself to draw conclusions about noise, which was your starting point to begin with? Do you understand how ridiculous is that?

Sensorgen do very interesting analysis because they compute factors which are not in the DXO data, like well capacity and read noise in e-. Those two parameters have a clear meaning unlike your "efficiency" one.

You misinterpreted my remark about the resolution of the system. Given the same noise curve, a system with better resolution has some advantage. You can apply some NR and have a lower noise and the same resolution as a lower res system.

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Anders W Forum Pro • Posts: 21,468
Re: Very simple:
2

bobn2 wrote:

Anders W wrote:

Just another Canon shooter wrote:

Anders W wrote:

Just another Canon shooter wrote:

Anders W wrote:

FF has the same noise for equivalent images only if the sensors are equally efficient. But as a rule they are not. Smaller sensors tend to be more efficient than larger. See here:

http://www.dpreview.com/forums/post/53189207

Not true. QE of newer sensors is about 53%, see sensorgen, from m43 to APS-C to FF.

Sensorgen doesn't have data for many of the sensors in my sample and are based on fitting curves to numbers that results from previous curve fitting.

It does, for the most relevant bodies.

Why should we use partial data if we can use more complete data? And why should we use fitted data points if we can use real data points?

Anders, if you have good data for a full range of cameras, why not publish it so we can all use it?

I don't have a website for things like these and don't intend to start one. Furthermore, my data are collected for the purpose of a set of specific analyses (those presented in the post I linked to) and are sampled and designed specifically to that end. I don't think they are of much interest for any other purpose.

But if you or anyone else want a copy of my Excel spreadsheet for the purpose of replicating or verifying what I have done, I am of course willing to share it. The raw data from which I start out are already available via DxO and, in line with scientific practice, I have already made it clear exactly which data I use and what I do with them. Hence, everyone has had the opportunity to replicate my analysis from the very beginning.

Then the sensorgen data with its acknowledged faults would be redundant.

I don't consider the sensorgen data redundant. I just don't consider them as well suited to answering the questions about sensor efficiency that I asked as those I was in a position to assemble myself.

As it is, your 'real data points' seem to be derived from exactly the same data and your method involves 'interpolation' - so the meaning or the word 'real' here is not maybe what most of us would think of as 'real'.

I have made it perfectly clear in which ways my data differ from those of Sensorgen.

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richarddd
richarddd Veteran Member • Posts: 3,300
Re: I found this video helpful
1

Levan wrote:

Glen Barrington wrote:

https://www.youtube.com/watch?v=DtDotqLx6nA

This video, while being correct, is very missleading for a begginer. It tells the truth, but not all of it. The reason, at least for me, is uknown. Beware, if you don't have enough information already.

Why do you believes it's misleading?  What is it missing?

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A photographer, who observes the world only TTL, can be a good craftsman, but not an artist.

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