I'm new to this group and interested that there is so much discussion
regarding lens quality. Of course the optics play an important role in the
quality of the final image but let's not forget the camera body. As an owner
of an OM4Ti for some years (and an OM2n before that) I have noticed a couple
of problems which can have a noticeable effect on image sharpness and would
be interested if anyone else has experienced them. I should stress that the
magnitude of these defects is such that they are only likely to be noticed
by the most critical users (most of the people here?!).
1. Focusing screen not positioned at the same distance from the lens as the
film plane. Therefore although the image appears in focus on the screen the
image captured on the film is not. There has recently been a discussion
regarding the use of other manufacturers screens in OM bodies. I wonder if
the thickness of these screen differs from the Olympus originals and whether
this causes focussing inaccuracies.
2. (This one is rather esoteric!) Flatness of the film pressure plate. When
I first used my OM4Ti I noticed on some shots that there was a small area on
each slide where the image was softer than the rest . Eventually I suspected
the pressure plate and upon examining It discovered a very slight 'bump'
that seemed to correspond with the area of unsharpness on the film.
Fortunately the pressure plate on my old OM2n is of identical design (but
flatter!) and I used it to replace the one in the OM4Ti curing the problem.
I believe that Contax produce(d) a camera with a ceramic pressure plate and
suction device to ensure the film is held completely flat, so presumably
this is a recognised area for concern.
Both of these problems are most noticeable using a lens with a small depth
of field (the 90mm/F2 that is receiving a lot of attention here should be
ideal for this!) and a high resolution film (e.g. Fujichrome Velvia).
Adrian
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