Archived posting to the Leica Users Group, 1998/01/19
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About 10 days ago I was shooting in Manhattan in Lincoln Center using my
R5(shame on me for not having Rn with n>5) with either the 28mm f2.8 PC SA
lens or 21mm f4 SA(Super-Angulon) lens. Sunshades were attached to the
lenses; the PC also had a B+W uva drop in filter held by the sunshade. There
was bright sunlight at a low angle, typical to the winter sun about two
hours from sunset. There is a lot of glass covering the Lincoln Center
buldings.
I took consecutive pictures of the same section of Philharmonic Hall with
both lenses. The sun was outside the frame. The photo taken with the 21mm
lens was free of flare at f8. On the other hand, the shot with the 28mm
PC(raised to one-half of its full extension), exhibits the classic features
of flare at f8; typically the contrast is lost in the area and several ghost
images of the diaphragm appear in the view. Here are some questions:
1. Have you experienced that flare/ghosts are more prone to
occur with PC lenses than with standard wide angle ones?
2. Is there something specific to the PC SA design that would
create the problem?
3. Would the drop in filter with its 2 extra glass surfaces cause
the flare/ghosts? This may be inconsitent with 5 ghosts of the diaphragm.
Note that the reflections of the sun by the glass surfaces will act as a
light source. Thus I would like an explanation for the relative immunity of
the 21mm lens to flare /ghosts in comparison with the 28mm PC lens.
Any comments are welcome.
Andrew Jordan
35 miles south of LEICA USA