Hyperfocal distance

Wilt wrote in post #2210338
Sandpiper, as has been pointed out, DOF is indeed format sensitive. Lots available on this topic, but to simply provide it to yourself, find a DOF calculation program and try it out.

I'll take your word for it, I'm too busy to check that out. I just don't see how a lens will project different circles of confusion dependent on how much of the image at the same focal plane is being recorded. I know that medium format etc is different, because the focal planes are different and the lenses aren't generally transferable anyway.

I confess that my 30 years experience of photography revolves around film and it doesn't matter how big a bit of it you stick behind the lens, so long as the focal plane does not change the image will be identical. I've only been shooting digital about 18 months, so if there is some way that the sensors react differently to the projected image it is a difference that has escaped me.

It doesn't affect the principle of hyperfocal focusing in anyway, whatever the difference may, or may not, be between the two formats. That was simply an aside with reference to a theory as to why DOF scales are no longer marked on lenses, rather than anything directly to do with the OP's original query as to how and why to use hyperfocal focusing.

sandpiper wrote in post #2211854
I just don't see how a lens will project different circles of confusion dependent on how much of the image at the same focal plane is being recorded.

Circle of confusion diameter is determined by the smallest dot a person can see on a print (usually 8x10 is the standard) divided by the magnification factor required to produce a print of that size. Therefore a smaller CoC diameter is typically used for smaller format cameras, since the image needs to be magnified more to produce the same size print. Most often, a CoC diameter of 30 microns is used for 35mm film, and around 19 microns for a 1.6x camera.

Agreed.