10-30-2010, 02:15 AM
[quote name='mike' timestamp='1288400012' post='3835']
I'm not sure what you don't understand? Many people in this thread talked about the shallower dof you can get with a FF. The converse is true also. [/quote]
No, it isn't. That's where you are wrong.
Well, I guess you never realized that because of the fact that noise on FF is a lot less, you can actually use higher iso to compensate and get faster shutter speeds, while still maintaining better IQ than with APS-C. The funny thing is that iso, DoF, diffraction, etc. is all in balance if you want to achieve the same DoF. The only thing different is that overall FF still wins on IQ, because noise is one of the characteristics not conforming to the cropfactor. In short, you should not only look at DoF but at all factors that are at play with regard to taking photographs, and you'll find that FF still does better on all aspects than APS-C, except for reach, as I mentioned. There is a reason why FF generally is considered to be better for landscapes than APS-C cameras ...
Furthermore, you can get away with a 1.6X slower shutter speed than with APS-C for the same FL, or exactly the same shutterspeed when FL is selected for the same AoV in order to get exactly the same amount of shake or movement blur. F.e., a 15 mm FL on APS-C requires at least 1/(15*1.6) s = 1/24 s shutterspeed, while for the same AoV on FF you would need a 24 mm lens requiring 1/24 s (the crop factor is 1 for FF). IOW, APS-C does not have an advantage here at all.
Regarding TS lenses: I don't think you entirely grasp the concept. You don't get more DoF with TS lenses. TS lenses allow you to place the plane of focus more effectively, which allows one to create the illusion of more DoF, or less DoF for that matter. Tilting doesn't magically create more DoF. And generally speaking, using a tilt setup does not make for a good compensation for subject movement. The only thing that does, is shutterspeed. And here APS-C certainly does not have the advantage.
A few comments on the article by Bob Atkins: this is rather general stuff, with some equations thrown in to make it look less general.
Ever heard, f.e, of the diffraction limit? That sets in 1.6X earlier with APS-C than with FF, which is exactly why you can only achieve the same deeper DoF with APS-C as with FF, but FF gives you the benefit of shallower DoF too. BTW, this is also true for cameras with even deeper DoF. A camera with a cropfactor of 6 may seemingly have much deeper DoF, but that is only true while diffraction doesn't cancel out DoF sharpness, diffraction sets in even faster with these cameras, namely the same factor 6 faster.
Furthermore, anybody who has done a lot of photography knows that the hyperfocal distance is something that generally doesn't work too well. Why? Simply because it doesn't necessarily put the main object or subject in a photograph in the sharpest focus. And with digital this is even worse than with film, because film has a CoC-buffer if you like, equal to the thickness of the film emulsion (0.2 mm), which digital doesn't have.
Neither does APS-C suddenly gain on FF for hyperfocal distance if one chooses to use it regardless, provided one uses an equivalent aperture and the same AoV.
In short, knowing now where you are coming from makes me understand better what you were trying to say. However, the way I understand it now, it is based on partly incorrect assumptions or partial knowledge, which is why I was thrown off.
Regards, Wim
I'm not sure what you don't understand? Many people in this thread talked about the shallower dof you can get with a FF. The converse is true also. [/quote]
No, it isn't. That's where you are wrong.
Quote:Assuming a crop factor of 1.6, for the same fov (which is really what matters) you get at least 1.6x more dof for a given aperture. Therefore, with a 12mm instead of a 18mm focusing at a hyper-focal distance I can get from closer to the lens to infinity and with the ability to use a faster aperture. With the FF you may not be able to step down enough, or if there's a breeze, the shot will be longer and this will show up.
Well, I guess you never realized that because of the fact that noise on FF is a lot less, you can actually use higher iso to compensate and get faster shutter speeds, while still maintaining better IQ than with APS-C. The funny thing is that iso, DoF, diffraction, etc. is all in balance if you want to achieve the same DoF. The only thing different is that overall FF still wins on IQ, because noise is one of the characteristics not conforming to the cropfactor. In short, you should not only look at DoF but at all factors that are at play with regard to taking photographs, and you'll find that FF still does better on all aspects than APS-C, except for reach, as I mentioned. There is a reason why FF generally is considered to be better for landscapes than APS-C cameras ...
Furthermore, you can get away with a 1.6X slower shutter speed than with APS-C for the same FL, or exactly the same shutterspeed when FL is selected for the same AoV in order to get exactly the same amount of shake or movement blur. F.e., a 15 mm FL on APS-C requires at least 1/(15*1.6) s = 1/24 s shutterspeed, while for the same AoV on FF you would need a 24 mm lens requiring 1/24 s (the crop factor is 1 for FF). IOW, APS-C does not have an advantage here at all.
Quote:IMO, one of the main advantages of the T&S lens on 35mm format for landscape is the ability to get a very big dof with a larger aperture than you could w/o it. This is particularly useful if there's any subject movement.
Regarding TS lenses: I don't think you entirely grasp the concept. You don't get more DoF with TS lenses. TS lenses allow you to place the plane of focus more effectively, which allows one to create the illusion of more DoF, or less DoF for that matter. Tilting doesn't magically create more DoF. And generally speaking, using a tilt setup does not make for a good compensation for subject movement. The only thing that does, is shutterspeed. And here APS-C certainly does not have the advantage.
Quote:There's a nice summary here: [url="http://www.bobatkins.com/photography/technical/digitaldof.html"]http://www.bobatkins...digitaldof.html[/url]
Note the first and last bullets.
Cheers
A few comments on the article by Bob Atkins: this is rather general stuff, with some equations thrown in to make it look less general.
Ever heard, f.e, of the diffraction limit? That sets in 1.6X earlier with APS-C than with FF, which is exactly why you can only achieve the same deeper DoF with APS-C as with FF, but FF gives you the benefit of shallower DoF too. BTW, this is also true for cameras with even deeper DoF. A camera with a cropfactor of 6 may seemingly have much deeper DoF, but that is only true while diffraction doesn't cancel out DoF sharpness, diffraction sets in even faster with these cameras, namely the same factor 6 faster.
Furthermore, anybody who has done a lot of photography knows that the hyperfocal distance is something that generally doesn't work too well. Why? Simply because it doesn't necessarily put the main object or subject in a photograph in the sharpest focus. And with digital this is even worse than with film, because film has a CoC-buffer if you like, equal to the thickness of the film emulsion (0.2 mm), which digital doesn't have.
Neither does APS-C suddenly gain on FF for hyperfocal distance if one chooses to use it regardless, provided one uses an equivalent aperture and the same AoV.
In short, knowing now where you are coming from makes me understand better what you were trying to say. However, the way I understand it now, it is based on partly incorrect assumptions or partial knowledge, which is why I was thrown off.
Regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
