>Do you mean the edges of the frame are diliberately non-straight?! If
>so, I'd better post a retraction. Do you know which manufacturers do
>this?
>
> -- David Jacobson
>
Hi-- Just about everybody, though I am not sure what is done where in
the finder. As an example, look at Nikon FM-FE finder using a micro-
Nikkor or any fixed focal-length Nikkor tele (lenses with no linear
distortion). Bring a straight line in the subject near to and parallel
with an edge of the finder. The mask is obviously curved to make it look
straight, since the image from the lens which is curved inward by the
vf optics is not parallel to the edge of the frame. Neat, huh? This is
also easy to see when a grid screen is used and no lens is on the camera -
the grid has an obvious pincushion distortion without any references, but
it is also clear that the edges of the frame are not parallel to the grid
(a straightened grid would force the frame edges into barrel distortion).
All Nikon finders since the FG-FE-Fm era except the "F" series exhibit
this distortion, and all Minoltas (therefore Leicaflexes), Olympuses,
Canons, etc. that I have seen also do this. The old Nikkormats, H1a's,
Ftb's, etc. didn't do it - my guess is that Olympus introduced the
problem with their compact SLR (making the bottom of the pentaprism
into a condenser may be the culprit - makes for compact construction
and bright finders, but.... (Then there is the added problem of
difficult off-center focusing with short lenses, and focus error near
the edges with long lenses.) David Ruether