Originally posted by jstevewhite Hyperfocal distance calculations use exactly the same math that produces DOF calculations, so saying it's a "film-ism" means that DOF is a film-ism. The same measures of "acceptable sharpness" are applied in calculating hyperfocal DOF as calculating other DOF.
OK, in that case I submit your original statement is incorrect. I thought you were suggesting that while DOF might be the same when comparing 135/8 on APS-C versus 200/11 on FF (for example), the hyperfocal distance is somehow different. That would have been new information to me, and I was willing to accept that as an interesting but not all that important fact. But ff you're actually claiming the DOF at 135/8 on is *not* the same (roughly) as at 200/11 on FF, that's just wrong. Any DOF calculator will tell you that.
This is the whole basis of what I'm talking about - a 200/4 on FF really is *equivalent* to a 135/2.8 on APS-C, assuming the 200/4 has that one extra tiny stop at the far end of the scale. Shooting the 200/4 on FF one f-stop down from wherever you shoot the 135/2.8 will produce the same picture in terms of FOV, DOF, and - on avergae, assuming similar sensor technology - same noise for a given shutter speed (because you'll need to shoot the FF camera one stop higher ISO, thus nullifying its inherent advantage there. people continue to not understand this concept and argue against, but these are simple basic physical principles - arguing against this is like arguing against the law of gravity.
Elsewhere it seems you are saying Bob Atkins makes some sort of special case exception for what happens as you approach infinitely small apertures and focus distance near the hyperfocal distance. This is the part I was thinking might indeed be valid new information, but I still haven't seen it explained.
What I meant by 'filmism" was using hyperfocal distance as a way of getting what one believes will be an acceptably sharp print. In the digital age, Few people are satisfied by "sharp enough as defined by DOF formulas". If your standards for sharpness are that low, then really, it probably is true you'd fine with any camera at all.
Quote: Limited to f/16? not sure what you mean.
I mean that my little hyperbole was based on the fact that most lenses have a minimum aperture that most people never ever use. If the minimum aperture of your lens is only f/16, then indeed, you'll probably run into this somewhat more often. I was just trying to emphasize how insignificant an issue that would be for most people, by suggesting some of the reasson why most people normally avoid f/32.
BTW, regarding pixel density - I was referring to its effect on *noise*, not resolution, when I said it was largely a myth.
Quote: Then 11x14 inch is the best?
Well, in terms of IQ, and assuming lenses could actually stop down far enough to get the same sort of DOF, then yes, certainly, obviously, intheory. But now you're dealing with other issues when it comes down to what can be made *in practice*. FF and APS-C are close enough to the same size that these concerns don't really come that much into play.
Quote: *Less DOF. Not "more DOF control", because stopping down another stop and a third is not the same thing as using a shorter lens.
Of course it isn't. Once again, I can't imagine any possible way in which you statement above could possible be seen as relating to anyone has ever seen. Obviously, stopping down isn't the same as using a shorter lens - no one in their right mind would claim that. But using a 200 at f/11 on FF *is* the same as using a 135 at f/8 on APS-C (well, within a fraction a stop). It's an unarguable physical fact. Either you accept it and then reframe your argument, or you deny it, and then I'll direct you to the readings that prove it.
Last edited by Marc Sabatella; 05-17-2011 at 11:44 AM.