Very interesting. I found it very surprising that the Celestron C90 did
so poorly. Despite the fact that it's a telescope being used as a
camera lens the only disadvantage that should impart would be
vignetting. As a telescope, the size of the secondary mirror and the
baffling really only needs to give good light to an area about the size
of the vertical dimension of 35mm film. Actually, I'm surprised that
the vignetting isn't worse than it is. But the image quality is a real
surprise.
As to the apparent non-difference seen in the image sizes between the
Bausch & Lomb and Celestron I speculate it may be due to the focusing
mechanisms. Some cat's focus by moving the primary mirror back and
forth and this has the effect of varying the focal length and
magnification for close objects vs. the specification for infinity.
Too bad you didn't get a chance to include the Zuiko 85-250/5 and the C8
2000/10. I don't own any of the glass that you tested but I do own an
85-250 and a C8. I would hope that the C5 and C8 as Schmidt-Cat's
(Celestron's claim to fame) could do better than the lower cost C90
Maksutov.
Chuck Norcutt
Jan Steinman wrote:
>
> Of course, you can't get away with that with just ANY mirror, as I
> hope my study shows. But the Zuiko Reflex appears to be up for that
> amount of cropping, and more.
> http://www.Bytesmiths.com/OM_Tele/index2.html
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