P3D Re: "Bowl" distortion in viewers

[erker@xxxxxxxxxxxxxx (Greg Erker) (by way of wier@xxxxxxxxxxxxxxxxx (Bob Wier))]

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[following up on what I wrote yesterday]

>  I don't normally have any flat photos to view
>but I did take a test roll (w/o moving camera)
>with my (then) new-to-me Bronica S2A.
>
>  I'll have to mount one of those "pairs" and
>see what kind of distortion my MF viewer has.

  Mounted two identical shots of my living room (stereo
stand and TV plus toys) in a RMM medium format mount
(50x50 mm). Viewed it in my home-made MF viewer which
has American Science and Surplus 40 mm dia by 84 mm FL
achromats (which do have pincushion distortion BTW).

  I didn't see ANY bowl effect. There was a very slight
tilt of the image away from me at the top which appeared
to be due to a bit of rotation in one image thanks to
my quicky mounting job.

  I should mention that my glasses (which I wear all the
time, including looking thru the viewer) have a lot of
distortion when I look through the lenses off center.
(So much that I usually don't trust my eyes to judge
if a picture is level). They have barrel distortion.
So perhaps my brain just filters out the bowl effect
because my glasses cause it every day.

  I'd like to hear if anyone else sees the bowl effect.

Regards - Greg E.

http://www.angelfire.com/ca/erker

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