Wouldn't be that simple, would it?
The way I interpret it (and I may be wrong, after all I used to think it was just aperture), it is more a combination of aperture and angle of view that affects diffraction. So you can use f-stop only as an approximation, but that ought to be close enough for most work.
In other words a 100mm lens at f22 on a 35mm camera has slightly less diffraction than a 100mm lens at f22 on a 6x9 camera does. Of course that is more than offset by the higher magnification needed with the 35mm image.
So, go ahead and use f-stop. With your istD the sensor resolution is probably below the diffraction level at the smallest f-stop anyway, in which case you can ignor diffraction.
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Steve Desjardins wrote:
Let me see if I have this straight:
The extent of diffraction is determined by the size of the aperture but the effect at the film plane also depends on the focal length of the length. Because both of these are involved, the property I should worry about in terms of effect on my pictures is f stop, which is the ratio of these two factors.
Yes?
-- graywolf http://graywolfphoto.com/graywolf.html
