Telephoto lenses

Question on 500mm-ish telephoto lenses for piggy back astrophotography. Has anyone tried a 500mm f/8 telephoto lens for astrophotography such as this one?

http://www.adorama.com/catalog.tpl?op=details&sid=10425104512240097&sku=SY5008PU

This same lens appears to be available under 3-4 brands for about the same price and can be had either in mirror format or the more conventional "all lens" format. Is there reason to believe one design would be superior to the other?

How about this one? The main attraction of this is the faster f/ratio, but it costs a bit more.

http://www.adorama.com/catalog.tpl?op=details&sid=10425104512240097&sku=PRO500

Are any of these viable or am I better off with something like a Synta 120 short tube OTA (600mm, f/5) for about $300? I understand that probably none of these will be perfect particularly near the edges. Perfection I seek not, but will they produce reasonably good results? Thanks.

I have quite a bit of experience with these type lenses. If you can find a 400mm Spiratone on the used market, other auction houses, even here on Astromart, you will be much happier. Another version was marketed by a company called Sterling Howard. They called it the "girl watcher" lens, and it was actually one of the best of the best.
Also, there were slightly shorter versions with many different names, but were around 350mm f/5.5. I have one of these and it is absolutely the sharpest telephoto I have ever used in the 300 to 500 range. I paid 10 bucks for it at a used camera shop! If you shoot color stop them down 1/2 to one stop. With B&W wide open with a yellow filter will give pinpoint star images, but be careful on your focus. Most of these lenses will travel beyond the infinity mark slightly. I have to back mine off about 1/16 inch for best results.
Hope this helps, and good hunting!

Walt

I have a 500mm f/8 mirror lens that I use for piggy back astrophotography. It give about a 2-1/2 X 4 degree field of view, with reasonably good results. I also suggest that you use a lens shade (I use one of the retractable rubber ones) to avoid stray light and to also serve as a dew shield.

This is one of my first attempts to photograph the Double Cluster.

With the low price of these type of lenses you don't have much to lose. Give it a try.

Lee

Attached Image:

Hey all, me again. Well it seems after checking the news groups the 500mm mirror lenses are generally considered pure rubish, but the pure lens design is said to be quite good and used they are a song. My only regret is the longish photographic speed (f/8).

Before I leap into this I just want to ask if any one has the Pro-Optic Maksutov mirror lens. I gather that it was also sold under the Orion and Celestron brands as a spotting scope and the mirror is columinatable (is that even a word??). It's much faster at f/5.6. I'm concerned it may have the same faults as the cheap Vivitar/Pheonix/Quantaray etc mirror lens (i.e. poor optics, given the price point). Can anyone confirm or deny? Thanks.