Quote:
Originally Posted by marki
Vader, the images I seen from these scopes (links are on this site somewhere  ) are far from being blobs.
Mark |
Look here
http://astro.uni-tuebingen.de/~grzy/APO.html
8" RC by GSO. Look at the star image. This is really blob. And this is in
almost perfect seeing conditions - in the air of laboratory. It will be really horrible under real sky.
Read numerical findings: Strehl is about 0.5. And with spherical aberration
removed. Without removing spherical aberration Strehl is lower than 0.25!!! I specially reprocessed these interferograms. No diffraction image at all. This is crap of a crap. Not a telescope. Image quality on a level of multilens telephoto objective, not better,
Of course, it will produce star images on CCD chip with sharpness of
ordinary telephoto. My Canon EF 200mm F/1,8 produce better images.
At the pointed website look at the upper tested telescope 16" F/10 ACF
Meade (former RCX) - it show Airy disk and first diffraction ring with
moderate optics roughness. But this scope being 2x larger is at least
5 better optically than tested below 8" RC by GSO.
However if you think that these cheaply made RC from GSO deliver
decent images, far from blobs, no problem - buy it and use it.
Wiser guys will, however, buy RCX or ACF alternatives.
If RC scopes can be produced cheap and smooth, believe me, there
will be a lot of these telescopes before these taiwanese guys introduced
their crap tubes as RC scopes.
No free lunch.
16" f/10 ACF
16" f/10 ACF