In a message dated 4/24/99 10:44:12 AM Pacific Daylight Time, Gary writes:
<< I haven't measured what I'm subjectively grading as vignetting and it's
falloff in f/stops, but I don't agree that improvement isn't had upon
stopping down the 18mm f/3.5
Here are the vignetting grades I've noted:
Vignetting = C (f/3.5), B-(f/5.6), B+ (f/8), A-(f/11 and 16)
If anyone has a densiometer, I'd be pleased to have them measure four
benchmark (A,B,C,D) slides for me. >>
Gary,
you may be able to make a crude densitometer by taping a thick piece
of black card over your OM2s (sans lens)
with a small hole punched in the centre. Line up the camera on a tripod in
front of a slide projector (with
no slide in projector ) as a roughly collimated bright light source. Place
your slide against card in front centered on hole, note
reading and adjust exposure compensation dial to keep exposure reading
constant as you move slide to
align measurement hole to near edge of frame. Exposure compensation should
now give estimates of fall-off/vignetting within 1/3 stop.
Tim Hughes
Hi100@xxxxxxx
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