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

Started Jun 15, 2014 | Discussions
OP oneohone Forum Member • Posts: 77
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

TransientEye wrote:

As others have pointed out, you need to scale the focal length and aperture by the crop factor in other to maintain the same field-of-view and depth of field. The main limitation of u4/3 lenses is the small number of really really fast lenses - the best options being the new 42.5mm f1.2 or the excellent Voigtlander manual focus lenses.

Something else that is usually ignored is that the ISO noise also increases with the square of the crop factor. So notionally, a 16MP full-frame at ISO 800 has the same image noise as a 16MP u4/3 camera at ISO200 (assuming similar sensor tech - true if you are used to Nikon, less true if you are used to Canon...).

If you are interested as to why, I have a blog post (with diagrams...) that tries to show how equivalence works.

Of course, real cameras have many more attributes that may matter more (like ergonomics, or Olympus' excellent image stabilisation).

Of course true, that's why I made a shortlist and went out to handle all of the cameras. From sample pictures the Oly on high ISO settings seemed satisfactory to me. I haven't quite decided yet on which one I will buy, but the Oly is looking very, very strong right now.

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baxters Veteran Member • Posts: 5,157
Re: I found this video helpful
3

oneohone wrote:

Thanks! I'll watch it when I have time!

I could only watch a minute before the condescending know-it-all attitude of the narrator made me stop.

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tokumeino Senior Member • Posts: 2,755
Photographic equivalence

Add this link as well : http://www.josephjamesphotography.com/equivalence/

About ISO : if you have a M43 f/1.4 lens which provides equivelence with f/2.8 on a FF (equivalence as defiened above), since 1.4 is a lower F-number than 2.8, you need less ISO (4 times less) to reach the same exposure with the same shutter speed. FF sensors have much better sensitivities, but they need to use much higher ISO to provide M43 equivalent pictures.

As said before, the problem is that you don't have many f/1.4 or less M43 lenses. And if you are looking for f/1.8 FF equivalence, you just can't do it with existing m43 lenses.

IMO, the OP choice relies on his need of equivalent apertures greater than f/2.8 or f/4 when in FF (depending on the FL and availability of M43 lenses). If the OP can't live with f/4 (FF speaking), then M43 is not well suited. If he can, then he won't get any trouble with M43. I had a similar reasoning before moving from NEX to M43 : since I always can easily do with apretures like f/2.4 in APSC, I'll always find equally or faster equivalent M43 lenses. And I spare money as well as weight.

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Sergey_Green
Sergey_Green Forum Pro • Posts: 12,001
Nice summary

Great Bustard wrote:

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT. By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse. So, unless low noise matters more to you than a deeper DOF, mFT will be a better choice than larger formats for handheld photography in low light.

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), and that is where the larger formats are often ahead regardless of what sensors they have. The dark shadows, on the other hand, is usually not where the least important information in the images is, and can be cleaned without ill-effects to the rest of the captured scene. That is, if anyone is bothered by it.

Here is a good example (this is from LTZ470),
http://acwilli.smugmug.com/Other/Jakes-B-Ball-Jan-2014-EM1-35/

As you can see there is a lot of noise in the images in general, but none of it effects the most important areas (middle-gray), where the most relevant information is. And the difference between larger and smaller formats in these areas is not that far off anyway, even if it mattered, which it does not.

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- sergey

Anders W Forum Pro • Posts: 21,468
Re: Nice summary but the supplement needs improvement
5

Sergey_Green wrote:

Great Bustard wrote:

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT. By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse. So, unless low noise matters more to you than a deeper DOF, mFT will be a better choice than larger formats for handheld photography in low light.

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

Here is a good example (this is from LTZ470),
http://acwilli.smugmug.com/Other/Jakes-B-Ball-Jan-2014-EM1-35/

As you can see there is a lot of noise in the images in general, but none of it effects the most important areas (middle-gray), where the most relevant information is.

On the contrary, for reasons already spelled out, such is not the case.

And the difference between larger and smaller formats in these areas is not that far off anyway, even if it mattered, which it does not.

On the contrary, the efficiency advantage of smaller sensors can be quite substantial at times, as illustrated for equivalent photos in the link below:

http://www.dpreview.com/reviews/image-comparison?attr18=lowlight&attr13_0=oly_ep5&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=-0.12336706531738732&y=-0.9872719691061603

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tokumeino Senior Member • Posts: 2,755
Re: Nice summary but the supplement needs improvement
1

I agree with your 2 ISO stops comparisons between M43 and FF. It's the only way to be fair. Comparing FF and M43 at same ISO (like many do) is pointless since to get equivalent pictures, FF will need 2 more ISO stops.

BUT... Sony FE lenses are f/1.8 for the 55mm, and f/2.8 for the 35mm. With M43, you would respectively need f/0.9 and f/1.4 for equivalence. But there are not suh M43 lenses and you can't get equivalence. Roughly, 1 stop is missing to M43 lenses.

If you had post DPR samples in good light I wouldn't have say the following, but since you draw low light comparisons, given existing lenses, it would make sense to compare M43 3200 ISO to FF 6400 ISO, IMO. And if you do so, Sony FF is better.

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Anders W Forum Pro • Posts: 21,468
Re: Nice summary but the supplement needs improvement
5

tokumeino wrote:

I agree with your 2 ISO stops comparisons between M43 and FF. It's the only way to be fair. Comparing FF and M43 at same ISO (like many do) is pointless since to get equivalent pictures, FF will need 2 more ISO stops.

BUT... Sony FE lenses are f/1.8 for the 55mm, and f/2.8 for the 35mm. With M43, you would respectively need f/0.9 and f/1.4 for equivalence. But there are not suh M43 lenses and you can't get equivalence. Roughly, 1 stop is missing to M43 lenses.

What about the CV 17.5/0.95, CV 25/0.95, and CV 42.5/0.95, the SLR Magic 12/T1.6, 17/T1.6, 25/T0.95, 35/T1.4, and 50/0.95 and the Panasonic Leica 25/1.4 and 42.5/1.2?

If you had post DPR samples in good light I wouldn't have say the following, but since you draw low light comparisons, given existing lenses, it would make sense to compare M43 3200 ISO to FF 6400 ISO, IMO. And if you do so, Sony FF is better.

First, my comparisons at a two-stop ISO difference are of course of interest regardless of whether equivalent lenses exist in a certain case or not. They show the results you can expect at the same DoF. If FF can open up more than MFT in terms of equivalent f-stops, it comes at the expense of DoF as Great Bustard pointed out. Whether you find that desirable or acceptable is a matter of your own personal objectives and requirements. Speaking for myself, I rarely want to go further in that direction than my fast MFT primes (all with max apertures in the range of f/1.7 to f/2.0) allow. If you do want or can accept ultra-shallow DoF, however, FF may indeed be preferable.

Second, if you look again at the link you provided for a comparison between MFT at ISO 3200 and FF at ISO 6400, you will see that even in this case, MFT wins for noise (although whether it does depends on which particular cameras we choose to compare).

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Anders W Forum Pro • Posts: 21,468
Re: Nice summary but the supplement needs improvement

Anders W wrote:

tokumeino wrote:

I agree with your 2 ISO stops comparisons between M43 and FF. It's the only way to be fair. Comparing FF and M43 at same ISO (like many do) is pointless since to get equivalent pictures, FF will need 2 more ISO stops.

BUT... Sony FE lenses are f/1.8 for the 55mm, and f/2.8 for the 35mm. With M43, you would respectively need f/0.9 and f/1.4 for equivalence. But there are not suh M43 lenses and you can't get equivalence. Roughly, 1 stop is missing to M43 lenses.

What about the CV 17.5/0.95, CV 25/0.95, and CV 42.5/0.95, the SLR Magic 12/T1.6, 17/T1.6, 25/T0.95, 35/T1.4, and 50/0.95 and the Panasonic Leica 25/1.4 and 42.5/1.2?

Ooops. I forgot to mention the new Handevision Ibelux 40/0.85 here.

http://www.43rumors.com/handevision-gets-a-price-and-preorder-in-us-2079/

If you had post DPR samples in good light I wouldn't have say the following, but since you draw low light comparisons, given existing lenses, it would make sense to compare M43 3200 ISO to FF 6400 ISO, IMO. And if you do so, Sony FF is better.

First, my comparisons at a two-stop ISO difference are of course of interest regardless of whether equivalent lenses exist in a certain case or not. They show the results you can expect at the same DoF. If FF can open up more than MFT in terms of equivalent f-stops, it comes at the expense of DoF as Great Bustard pointed out. Whether you find that desirable or acceptable is a matter of your own personal objectives and requirements. Speaking for myself, I rarely want to go further in that direction than my fast MFT primes (all with max apertures in the range of f/1.7 to f/2.0) allow. If you do want or can accept ultra-shallow DoF, however, FF may indeed be preferable.

Second, if you look again at the link you provided for a comparison between MFT at ISO 3200 and FF at ISO 6400, you will see that even in this case, MFT wins for noise (although whether it does depends on which particular cameras we choose to compare).

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Ontario Gone
Ontario Gone Veteran Member • Posts: 4,183
Re: Very simple:

Great Bustard wrote:

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT. By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse. So, unless low noise matters more to you than a deeper DOF, mFT will be a better choice than larger formats for handheld photography in low light.

Very well layed out. I would also like to add, no larger format has stabilization like Oly 5 axis, meaning at the times when subject motion (in low light) is slow enough to reduce SS, those larger sensors lose that noise advantage that is tied to their thinner DOF (and perhaps then some). This IBIS advantage can't be factored all the time as subjects may be moving, but sometimes is better than never.

Best case scenario, using a fast FF lens with a speed booster, on an EM1/5, on slow/still subjects would likely net less noise than any FF with the same lens.

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

Ontario Gone wrote:

Great Bustard wrote:

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT. By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse. So, unless low noise matters more to you than a deeper DOF, mFT will be a better choice than larger formats for handheld photography in low light.

Very well layed out. I would also like to add, no larger format has stabilization like Oly 5 axis, meaning at the times when subject motion (in low light) is slow enough to reduce SS, those larger sensors lose that noise advantage that is tied to their thinner DOF (and perhaps then some). This IBIS advantage can't be factored all the time as subjects may be moving, but sometimes is better than never.

In all fairness, larger formats offer IBIS too. Sony has it in FF (A-mount) and Pentax as well as Sony (A-mount) in APS-C.

Best case scenario, using a fast FF lens with a speed booster, on an EM1/5, on slow/still subjects would likely net less noise than any FF with the same lens.

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Ontario Gone
Ontario Gone Veteran Member • Posts: 4,183
Re: Very simple:

Anders W wrote:

Ontario Gone wrote:

Great Bustard wrote:

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT. By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse. So, unless low noise matters more to you than a deeper DOF, mFT will be a better choice than larger formats for handheld photography in low light.

Very well layed out. I would also like to add, no larger format has stabilization like Oly 5 axis, meaning at the times when subject motion (in low light) is slow enough to reduce SS, those larger sensors lose that noise advantage that is tied to their thinner DOF (and perhaps then some). This IBIS advantage can't be factored all the time as subjects may be moving, but sometimes is better than never.

In all fairness, larger formats offer IBIS too. Sony has it in FF (A-mount) and Pentax as well as Sony (A-mount) in APS-C.

Oh i know, i was just saying that even their OIS/IBIS isn't as good as the Oly 5 axis. I've used SLT IBIS and Pentax as well, it helps but it's in a different league. If subjects are slow enough, IBIS can allow lower ISO, which effectively lowers noise.

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Kevin Sutton
Kevin Sutton Senior Member • Posts: 1,055
You should have kept going...

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

Cheers Kevin 

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photogeek Senior Member • Posts: 1,392
Don't shoot for equivalence

Personally I had two systems for a while, Fuji X and MFT. Sure, Fuji X is better at high ISOs, and sensor is larger, so if you want it, DOF is shallower. But you know what? MFT has a lot going for it too, so much in fact, that I sold my Fuji body and lenses and went with MFT exclusively.

Basically, compared to Fuji, my E-M1 has faster focus, better metering, better automatic white balance, better build and ergonomics (this is subjective, of course), and _much_ smaller and lighter lenses. The last point should not be discounted, the best camera is the one you have with you. And if that wasn't enough, it also has an excellent in-body image stabilizer and better video mode, too. Sure, it's no good above ISO1600, but at ISO 1600 it's better for shooting at much lower shutter speeds due to IBIS.

Anyway, the point is, the sensor is not "be all end all", other factors matter a lot. Think about it this way: your camera can easily make shooting pictures a joy or a constant chore. Oly gets much closer (for me) to making it a joy than any other camera I have used, in spite of its shortcomings.

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

Ontario Gone wrote:

Anders W wrote:

Ontario Gone wrote:

Great Bustard wrote:

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT. By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse. So, unless low noise matters more to you than a deeper DOF, mFT will be a better choice than larger formats for handheld photography in low light.

Very well layed out. I would also like to add, no larger format has stabilization like Oly 5 axis, meaning at the times when subject motion (in low light) is slow enough to reduce SS, those larger sensors lose that noise advantage that is tied to their thinner DOF (and perhaps then some). This IBIS advantage can't be factored all the time as subjects may be moving, but sometimes is better than never.

In all fairness, larger formats offer IBIS too. Sony has it in FF (A-mount) and Pentax as well as Sony (A-mount) in APS-C.

Oh i know, i was just saying that even their OIS/IBIS isn't as good as the Oly 5 axis. I've used SLT IBIS and Pentax as well, it helps but it's in a different league. If subjects are slow enough, IBIS can allow lower ISO, which effectively lowers noise.

According to optyczne.pl (aka Lenstip when translated into English), who actually test stabilization systems, the Pentax K-3 manages about 3.5 EV. The E-M1 reaches about 3 EV.

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Levan Regular Member • Posts: 265
Re: I found this video helpful
1

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.

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alcelc
alcelc Forum Pro • Posts: 11,861
Re: Understanding the Basics and how digital are or are not exactly ..

Franka T.L. wrote:

Well nor exactly fellow thru with standards ... that is well we shall get to that later alright

Now FOA, there is no such thing as croo factor, that term is grossly misused by people who only want to think of measuring a lens coverage as per 35mm film ( still capture ) as somewhat a holy grail .. so they say you have 2.0 crop factor on 4/3 sensor, But wait that camera do not crop anything when they capture, its just having a different size sensor. Just as in old days when I put my Hasselblad Zeiss 80mm standard on my Nikon FM2, I do not say its getting a crop factor of so and so. I say its an 80mm lens and well that's the same for any digital DSLR or mirrorless. Lens focal length and aperture is a PHYSICAL property of the lens and it does not change whether you use it for film or digital, 35mmm or 4/3 .. the only time one can say crop factor perhaps ( somewhat ) is when one shoot on a digital platform and set for in camera JPEG that's not native to the sensor aspect ratio. Say you set the M4/3 camera to shoot 16:9 HD format JPEG, then the camera indeed is cropping from the top and bottom of the said sensor ( which is 3:4 aspect ratio sized ). I term these misleading issue " Equivalent Coverage " as that's what it is. So a 25mm lens for 4/3 is having a equivalent coverage as a 50mm lens on 35mm still film capture. Mind that there' some caveat .. when we say equivalent ( or when they talk crop factor ) its measured on the long axis length wide and the coverage measured in degrees of measurement ( go back to high school math ) But if you tally the Math you can tell the factor for equivalent 4/3 lens coverage when used in Portrait format is in fact more like 1.9 as the 4/3 sensor is of course 4:3 aspect ratio when 35mm film is 2:3

So for your said M4/3 prospective needs you are looking at a M4/3 body with a 25mm lens and there's several, Panny has a 1.4 and Oly has an 1.8 both are speedy enough I shall say. And the standard lens can easily be complemented by equally good fast long focal / short Tele Macro like the Panny 45mm Macro / Oly 60mm Macro / Oly 45mm/1.8 or Zooms of various speed. Less choice on the wide end but they are there. And speaking of aperture, again they are physical to the lens and independent of the format of the said recording medium. So a said scene , being composed for exposure at ISO 100 needing f/4.0 at 1/125 shutter will still need that same exposure at ISO 100 when using your good old trusty Fujifilm Astia or whether you are using that new M4/3 set at ISO 100 ( effective, see below ) and no matter what kind of lens that might be.

One thing though, where we old film guys might need a new understanding is the speed of the medium , aka ISO setting for the film ( which is in build when we load the film ) and for these digital platform. Now here's a little fact that the Mfr probably do not really want to show around. The reality with almost all of todays digital platform is that they almost all cheat on the ISO setting . Not like film days when ISO had a rigid requirment for Film, Mfr to place a Ei / ISO setting on the film. The film must be able to reproduce that exposure set for a set light intensity to reproduce a set result to say it had that ISO. So when we load a ISO 1600 film we know we can safely use any measure to expose the film so long our exposure is based on calculating the medium to have an ISO 1600 sensitivity.

Well, no so for Digital platform. Their setting generally are over inflated. Say for the typical M4/3 camera, on a less than sunny day when we might want to use ISO 400 or ISO 800 so we can safely handheld and still use f/6.3 for that DOF. So we expose for that and WOW, that exposure just do not seems right .. because what , brasue almost all of the M4/3 bodies ( whichever model and brand ) had lablr their ISO in what they fashion as so. So ISO 400 on their camera is more like just having ISO 250 and ISO 800 is more like ISO 500 or even less. And this is also non linear Say if you take that same body and set the camera to ISO 3200, in most case you are only getting ISO 1200 and not 2000 ( as a linear rule would do ). So for anyone migrating from film to digital, there is a need to learn how the specific body ISO acually perform as ISO goes. The reason behind that is complex but mostly that had to do with the in camera JPEG which apply a tone mapping and the camera is usually configured to not to lost the highlight while boosting the shadow and then apply NR to made the exposure. Its not something magical, just the way it is. And for people who are more akin to shoot RAW or expose for control instead for in camera then one must realize this bit and work along it, and this is digital all of them, not just M4/3

So with old days and low light goes, most of us actually choose a fast lens not becasue of the speed but for the wide liberty to place exposure. And we trust our film to give that speed they labelled ( I swear on Ilford HP4 ) And we can do pretty much the same digitally, only for the fact that we need to work out our own effective ISO for the said body we choose. So if you have a particular setting for in camera JPEG you would want to test out to made sure that ISO 400 on that body is really how ISO 400 work for you, or might be you need to tune it up or down another notch or so. I shoot RAW, and do not particularly use Mfr's own processing and I've found DxO Mark's sensor review data of effective ISO pretty accurate ( as when I measure the exposure against my good old trusty calibrated light meter ).

There are other things to consider when switching from film to digital , but somehow we need to have a starting point right .. and getting the basic exposure right and in control is perhaps the first thing on the agenda ( other than actually going out and buying the gear in question )

Dear Franka, in very short can I say: assume the ISO is the same for a certain FF and MFT, then, for a particular scene if the FF can properly expose at 50mm FL, ISO 100, f/2.8 and 1/60", a MFT could have the same equivalent coverage (FOV) and same exposure at 25mm FL, ISO 100, f/2.8 and 1/60". The only difference is FOD?

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

Great Bustard wrote:

oneohone wrote:

I am in the market for a DSLR/mirrorless camera and after initial research and trying various cameras the Olympus M10 has made my final shortlist. Now I have some experience shooting 35mm film and in my experience I often take my 50mm f1.7 lens which I enjoy a great deal and it s a good fit for the types of photography I do, candid street, a little landscape and also portraits.

Now I wonder, I have mostly shot film (not counting snapshots with my cellphone) and then crop-factor never enterted my mind. The M10 has a larger crop factor than the other cameras on my shortlist (1.5 or 1.6) how does that impact the choice of lenses? To get something similar to the 50mm focal length I would need a 24mm lens, but what about aperture? If I understand correctly (and maybe I don't) aperture is also influenced by crop factor, then how is it possible to get a f.2.8 lens or lower for the m10? And how does that further influence low light performance? I often take pictures in low light without flash or tripod and from my experience with the film camera I often use f.2.8 or lower.

I know the M10 is a good camera, and the m4/3 system is also really good, and obviously people are satisfied using this system, but I just need a little help understanding the problem with low light and lens selection for the m4/3 system.

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT. By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse.

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.

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.

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

Just another Canon shooter wrote:

Great Bustard wrote:

oneohone wrote:

I am in the market for a DSLR/mirrorless camera and after initial research and trying various cameras the Olympus M10 has made my final shortlist. Now I have some experience shooting 35mm film and in my experience I often take my 50mm f1.7 lens which I enjoy a great deal and it s a good fit for the types of photography I do, candid street, a little landscape and also portraits.

Now I wonder, I have mostly shot film (not counting snapshots with my cellphone) and then crop-factor never enterted my mind. The M10 has a larger crop factor than the other cameras on my shortlist (1.5 or 1.6) how does that impact the choice of lenses? To get something similar to the 50mm focal length I would need a 24mm lens, but what about aperture? If I understand correctly (and maybe I don't) aperture is also influenced by crop factor, then how is it possible to get a f.2.8 lens or lower for the m10? And how does that further influence low light performance? I often take pictures in low light without flash or tripod and from my experience with the film camera I often use f.2.8 or lower.

I know the M10 is a good camera, and the m4/3 system is also really good, and obviously people are satisfied using this system, but I just need a little help understanding the problem with low light and lens selection for the m4/3 system.

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT. By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse.

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).

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

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.

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.

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

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. 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. 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.

What FF can do is to take non-equivalent images, as simple as that. When you must take equivalent images, there is still a resolution advantage, but there is no IS (sometimes) disadvantage and the lower DR at high ISO you mentioned, with the current sensors.

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Ontario Gone
Ontario Gone Veteran Member • Posts: 4,183
Re: Very simple:
1

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.

Many will assume MFT is more affected by diffraction if we compare a MFT @F2 vs FF @F4. This is not true, since the entrance pupils are going to be even.

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.

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