Archived posting to the Leica Users Group, 2001/02/08
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Mark Rabiner jotted down the following:
> But i think people who shoot that stuff, large format stop down almost all the
> way anyway.
I always thought that diffraction is dependent upon the absolute size of the
aperture, not the aperture number. f/16 for a 24mm lens for 35mm film is
going to be a much smaller diameter hole than f/16 on a 90mm lens for 4x5
film, hence LF shooters can use what appear to be much smaller apertures
without suffering from diffraction as much.
HOWEVER: Check this link for a more informed argument and some theory:
http://www.cs.berkeley.edu/~qtluong/photography/lf/fstop.html
...and scroll down to the "Diffraction" heading (about 1/3 down the page).
I think that the conclusion to draw from this is that while diffraction
remains constant for f-numbers across focal lengths for a given camera, it
varies between cameras and film formats, depending upon back-focus distance.
M.
- --
Martin Howard | "It's such a fine line between genious
Visiting Scholar, CSEL, OSU | and stupidity."
email: howard.390@osu.edu | -- David St. Hubbins
www: http://mvhoward.i.am/ +---------------------------------------