I own an F100 with the quirk of nonconsensually changing aperture on both my f2.8/105mm micro and my f4/200mm micro. In aperture priority mode, set at the largest aperture and focused close, I have f2.8 (or f4 on the 200mm). As I focus to farther and farther distances, the aperture will close down to f5.6 or even f8. Nikon service has had the camera twice in the last two and one half months and so far is unable to acknowledge the problem and/or test for it. Anyone else have this problem?

Tala altphoto@mindspring.com tala@empirewest.com(weekdays)

-- Tala Brandeis (altphoto@mindspring.com), April 14, 2002

Answers

Tala,

As you move the focussing ring you are also changing the macro ratio (ie. the size of the image on the film). This will also change the EFFECTIVE aperture of the lens in close focus (focusing adds significant extension to the lens). Therefore, a macro lens set to f/2.8 and close focused will no longer let in f/2.8 of light. Instead it will let in less light. The Nikon system shows you the new effective aperture.

Your equipment is working fine. You may want to read the following link which touches on this topic (look under the section labelled "Handling"): http://www.photo.net/nikon/60-2.8-macro

Btw, this will not happen with non-macro prime lenses. On a 85mm f/1.8 lens, the aperture will not change as your refocus.

good luck -Ray

-- Shourya Ray (sray1@hotmail.com), April 14, 2002.