Within depth of field range just as sharp as exact focus?

[Richard G]

"Exact focus" as you're interpreting it (as in: "always sharper") doesn't exist. DOF will always be "in force", when using a (proper) camera lens, etc etc etc:


http://en.wikipedia.org/wiki/Depth_of_field

I've been looking in on this thread occasionally. This looks misleading to say the least. Your Wikipedia quote alone is strong rebuttal.

 

[Richard G]

I was applying the following logic to the resolution of digital sensors in particular (e.g. a 6Mp vs 36Mp 35mm digital sensors, with the same lens mounted):

Substitute capture for display in the above and you'll see what I'm getting at. I think a low res sensor will resolve a slightly defocused blur circle as sharp, while a hig-res sensor will be able to accurately record the defocus.

I'm assuming the same would apply to large-grain vs very fine grain film. A fine grain film would be able to more accurately record a defocused blur circle than a large grain film, which would record it as sharp. So the fine grain film would, theoretically at least, record a shallower dof than a coarse grain film.

Perhaps others here may have done this comparison? Theoretically, it makes sense to me.

A corollary of this is reasonable shutter speed for film versus digital. I am noticing an increase in sharpness with tripod or other stabilization even with wide angle lenses at 1/125s on the M9 that I never noticed with Tri-X.