Long MF Prime?

my vote still stands for the Tokina 80-400.

braduardo wrote in post #2085334
Cool... Good information... I've kinda been wondering about some of this stuff myself. One other thing I personally have wondered about is a telescope mount... I've noticed that telescopes aren't nearly as expensive as they used to be, and the reach you can get is pretty amazing... How would one go about hooking up something like that?

Remember that telescopes are designed to provide a very sharp image at a point of focus--the image is projected in air for direct viewing with an eyepiece. Camera lenses are intended to provide relatively even quality over the width of a frame, because the image that matters is projected onto a much larger sensitized surface.

Also, camera lenses are optimized for apparent sharpness at a modulation transfer of, say, 30-50%, while telescopes are optimized for fault-free rendering of the diffraction rings around points of light (stars), which is more like a modulation transfer of perhaps 10%. Different objectives get different results.

Some will do well for both. In the end, however, you generally get what you pay for. The most expensive telescopes will perform better as camera lenses, but they are just as pricey as camera lenses that will perform better corner to corner.

The Schmidt-Cassegrain telescopes, such as those by Celestron and Meade, are designed (to some extent) for both. The typical 8" Celestron has a focal length of 2000mm, but it's design is fundamentally similar to mirror camera lenses. Don't expect much contrast when using a 2000mm lens for terrestrial photography. And you'll spend LOTS for a tripod of adequate stability.

Rick "thinking astrophotographers are the ultimate equipment geeks, with the ultimate expenditures when shooting thorugh the primary scope" Denney