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kwalsh wrote:
Are you honestly asking why things that are provably wrong persist on the internet? And are you further asserting that despite the already recognized logical fallacy of "appeal to authority" that we should instead "appeal to the masses" when answering provable technical questions instead of actually just doing the math ourselves? Anyway, sorry to be unnecessarily controversial, but it just struck me as an unusual position to start from.
The answer is simple. For any "depth of field advantage" that a smaller format might be believed to have the larger format simply stops down to a smaller aperture to match. When the larger format does this it of course loses any "advantage" it has over the smaller format as far as noise goes. Because the larger format stopped down if it needs to keep the shutter speed it must raise its ISO and as a result its noise performance now matches the smaller format.
This is the classic example of "equivalence" and is demonstrated innumerable times across various photography websites.
You appear to in fact agree with it below.
So no, there is no "m34 depth of field advantage". You can take the very same photo with a FF camera that you can take with an m43 camera as far as depth of field goes. The final images will have the same noise. Indeed, in this case neither camera has any advantage over the other as far as DoF and noise goes. They are equivalent.
There is a significant fraction of people that erroneously believe that m43 can take deeper DoF images than FF cameras. That if you need deep DoF you are better off shooting m43. That's simply not true.
What is true, if we are looking for m43 advantages, is that if you have no need for shalllow DoF then there are quite compact lenses you can buy in m43 that just don't have FF equivalents that physically small and light (like the 15/1.7 for example). The FF system can still shoot the very same image, you'll just end up hauling a bigger lens around for shallow DoF effects you might never use.
There are two caveats to the above. First, if you want to get deep, deep into diffraction territory then you may find m43 lenses that stop all the way down to F/16 while a FF lens might also stop at F/16 or only go to F/22. In those cases the m43 lens would be able to get deeper depth of field simply because of the limiting smallest aperture of the FF lens. In general people avoid shooting at such apertures though. And of course the effects of diffraction scale perfectly with sensor size. So the m43 shot at F/8 has the same diffraction effects as F/16 on FF.
Second, in macro shooting the pupil ratio of the lens begins to matter a lot. Because of the similar flange focal distances of all mirrorless formats regardless of sensor size this could in theory result in a potential DoF advantage for one format or the other. I'm simply not familiar enough with the macro lenses available to know if this is reflected in reality or not, but it is a possible theoretical advantage for achieving wider DoF with one or the other system.
It appears you understood exactly what I was saying. You seem to have now confused things by appearing to think I said there was a "FF advantage". That's not what I said, I said there was no "m43 advantage". Which is true, all I have to do to match the m43 shot is stop down the FF system.
This is a potential FF advantage, you can get shallower DoF with a FF system that you simply can't get with a m43 system. Not important to everyone though and some people would prefer carrying lighter equipment and more money in their wallet than chasing that FF "advantage". Plenty of people find razor thin DoF more of an affectation than an advantage as well, so if shallow DoF isn't to your taste that's one potential FF advantage that is of no use.
No, the FF camera just stops down to get the very same DoF and same noise performance as the m43 system. No win for m43. Just a tie.
And that's the larger point of "equivalence". In a very large range of shooting conditions it usually just comes up as a "tie". No advantage for either system. In a limited set of circumstances FF can have a final image "advantage" by which I mean do something not possible for the m43 system to ever do. There are really no conditions in which the m43 system can create an image that the FF system can't equally create just as well. But again, be prepared to pay more and carry more to have the potential to use that FF "advantage". For most m43 users the very real and persistent advantage of smaller kits of gear outweighs the occasionally encountered advantages of FF systems. For others, if their shooting regularly intersects with where FF can have an advantage they'll make the opposite choice.
Horse, courses, all that. But nonetheless, yes the internet and photography forums are full of persistently repeated fallacies and anyone that's been doing this for very long has seen them come up constantly. Some do get retired over time thankfully!
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This is a well written and informative piece that illustrates the usefulness of understanding photographic equivalence.
I like your referring to equivalence as "a tie."
I shall digress: I have the unfortunate feeling that what "a tie" means is not commonly understood. The confusion is typically about the aperture and ISO. A myth is that since the same f-number and the same ISO value on systems of different formates mean the same, and correct, exposure, then the systems give equivalent photos.
Of course, a "tie" or equivalence explicitly implies that two different formats can never be equivalent when equally exposed(!), only when the same total amount of light falls on the sensors (the size of the sensors being totally irrelevant).
(I use "exposure" as defined, for example, in Wikipedia: "In photography, exposure is the amount of light per unit area reaching the surface of an electronic image sensor").
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IDK because it's faster/easier than ever nowadays to remove sticks/twigs, and, things from an image.