In article <4r29k0$gdh@newsbf02.news.aol.com>, bhar782@aol.com says...

>I am considering the purchase of a Nikkor Rflex lens such as the 500mm f8
>or the 1000mm f11. Has anyone had any experience with either? How well
>do they compare to dedicated mirror makers like Celestron or Meade? How
>about vs reflex teles?

There have been two versions of the Nikkor 500mm f8 (plus a 500mm f5),
and one version of the Nikkor 1000mm f11. I have tried all but the
500mm f5. I recommend the larger, older, non-macro version of the 500mm
f8, which is quite sharp (especially for distant subjects) - roughly
equal in image quality to the big ED Nikkor teles at their wider
apertures (fine resolution, with slightly reduced contrast - quite good!).
It also is very good with the TC14/14B converter. The 1000mm was not
good enough for me, and the compact 500mm, while good, was a notch below
the older version. As with all mirrors, true speed is slower than rating,
there is a "hot spot" in the center of the frame (drop ASA rating about
1/2 stop to compensate when using the camera's [center-weighted] meter),
out-of-focus bright spots are rendered as "doughnuts", and (being
physically light and short) they are hard to hold steady (the cause
of many people thinking they are not sharp, I suspect....). I have had
good results hand-held with 1/500th second exposures (I shoot 4 identical frames to get one optimally sharp one). A gun-stock or gyro-stabilizer
can drop the sharp shutter speed to about 1/125th second. If you use a
tripod, pre-release the mirror, and weigh down the lens (many sturdy
tripods are not steady, and will vibrate enough to spoil sharpness with
a 500mm mirror). Though there is no diaphram with which to increase DOF, slightly out-of-focus areas are rendered in a contrasty way by the Nikkor,
and this results in greater apparent DOF than would be normal with a 500mm lens at f8. I like mine a lot, and find it a good compact alternative to
the big, expensive, fast glass when speed is not an issue.
Hope This Helps