Pentax PF-65ED for astronomical viewing?

Hello -

I plan to buy a spotting scope primarily for bird and wildlife viewing (so size and weight are important to me). Although I know little about astronomy, I will be using the scope in a place blessed with extremely dark skies and low humidiity, and it seems a shame not to take advantage of this! My current thoughts are to either get the new Pentax PF-65ED or find a used Televue Ranger or possibly a used Pentax PF-80ED.

Would the Ranger offer any particular advantage over the Pentax scopes for astronomical viewing? Both Pentax scopes take standard 1.25" eyepieces, so finding appropriate eyepieces for them should not be a problem. And would the 65mm objective of the Pentax 65ED be a seriously limiting factor, compared to the 70mm objective of the Ranger and the 80mm objective of the 80ED? I'm entirely new to astronomy, and have no idea at this point what particular kinds of viewing I'd be most interested in. I love the size and weight of the 65mm Pentax, and optically it apparently compares very favorably with its big 80mm brother.

Any advice greatly appreciated!

Zack,

I have a PF80 straight-through that's only about 3 lb. I mount it side-saddle style via a small ballhead on a carbon tripod. 8 lb total including the XL zoom EP. I did try using it for astro -- it turns out one could focus at infinity with a "barlowed diagonal", after a fashion. With some more work I think it could be made practical, right now it isn't quite useable. A 45-degree PF80 might work OK without mods. Yet another approach for astro is to fashion a periscope-like attachment to the front, holding a 3.1" elliptical diagonal, if you know what I mean.

-- William (Saratoga, CA)

p.s. I might list the PF80 because a 4lb 4" Borg is due to arrive next week