At 07:55 1/15/01, Acer asked:
i dont think so; i haven't personally examined the pics now since i don't
have them handy, but there are other scans, same lens:
http://albums.photopoint.com/j/View?u=380427&a=9125406&p=31108139&Sequence=0&res=high
note wood strips in ceiling before the brass thingy (drop down fire
sprinkler), they bow down
note "break" in tile in the floor, 1st from bottom edge, they bow up.
May have slight pincushion in this one too, but I don't really notice it on
the sides. Since this is a vertical shot, it's possible the top and bottom
are nearer the edges of the image circle and therefore show it more.
on a related note, is the following the same kind of distortion or is it
the so called wide angle distortion that makes things at the edges go
stretchy?
http://albums.photopoint.com/j/View?u=380427&a=9125406&p=31228289&Sequence=0&res=high
note round bottle/jug/whatever it is called at extreme right...it's not
round. note edge of shed at right, it is straight! what's going
on? cropped from left so you can't see it on that side.
In the extreme right corner, the base of the bottle looks oval, as well it
should in an extreme corner. This is normal rectilinear lens
behavior. The shorter the lens, the more noticeable it becomes. However
the right vertical edge of the bottle looks to show some pincushion. I
would expect that edge to be straight and just the base with an oval. Hard
to really tell as it looks like you may not have had the camera level so
the lens axis would be perpendicular to the window blinds. The edge lines
do look straight.
I believe that pincshion and barrel can be mitigated with the lens stopped
down, in which the diaphragm blocks ray paths around the edge of the
lens. Gotta think it through more about what happens optically under those
conditions.
Wayne is right about the possibility of aberrations being introduced during
printing and/or scanning . . . something I had not thought of. We have a
scanner at work that tends to tilt images, and one must sometimes rotate an
image back to get vertical lines parallel vertical image edges.
-- John
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