Hi, David and all.
>On the 500mm. If anyone knows, How good for piggiback astronomical pictures
>of the sky. I tend to think that it may be a good cheap alternative to
>buying a much more heavier Celestron telescope.(also f8)
I have no experience with the Zuiko reflex 500/8, but I had a Tamron SP
500/8. This lens is quite difficult to focus for astropics -- of course,
its helicoid goes way beyond infinity, so it *must* be focused 'at'
infinity. My only astropic attempt with this lens, 20 min. exposure,
tracked but *without* guiding corrections:
<http://217.216.177.119/web/cjss.galeon.com/zuiko/astro/m57.jpg>
Yes, the *softer* trail at the centre is the Ring Nebula (M57) ;-)
After that, I got a Zuiko 300/4.5 and later sold the Tamron. Easier
focusing and much larger aperture, but difficult to balance when
piggybacked on my 6" reflector scope:
<http://217.216.177.119/etc/m31.jpeg> 10 min exposure (tracked & painfully
guided ;-) just before the clutch on my scope's mount broke -- not sure if
directly related to the lens...
Maybe this lens would work best on a big, rugged mount/scope.
However, my best experience on piggyback astrophotography is with the Zuiko
200/4: great sharpness wide-open (without the slight coma of the 300/4.5)
and, best of all, a remarkable balance -- almost no guiding corrections
needed:
<http://217.216.177.119/web/cjss.galeon.com/zuiko/astro/m4.jpg> 2 min on
Sensia 400 pushed +2
<http://217.216.177.119/web/cjss.galeon.com/zuiko/astro/m42.jpg> 4 min on
E200 pushed +2
Maybe this 'ease of motion' (?) makes this lens prone to shake in 'normal'
pics, thus the usual critics on it.
Hope this helps,
...
Carlos J. Santisteban
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<http://cjss.galeon.com>
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