Canon’s new 600mm and 800mm lenses

Started 3 months ago | Discussions thread
Jack Hogan Veteran Member • Posts: 7,493
Re: Plane of Best 'Focus'

Joofa wrote:

Jack Hogan wrote:

Where is best 'focus' from a photographer's perspective? W is p-v OPD in microns, N is f-number. The minimal geometric CLC occurs further than suggested by minimum RMS.

The plane of best 'focus' in the center of the field of view in practice

FWIW, the 'plane of best focus' using only diffraction effects (not geometrical) can also be defined in a number of ways. Here is one way as in the link below - note that for usual photography it doesn't matter much, though, because of the range of typical F#'s. So it is more instructive. But, outside that range it has a marked effect. And, it is interesting to note it goes against the thinking that smaller cone angles are covered better with paraxial optics:

https://www.dpreview.com/forums/post/60963794

That's an interesting post and thread Joofa.

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