So ive been looking at getting into celestial photography. I want to be able to take shots of not only the moon, but planets in our solar system, and possibly some nebula. My problem is that i really dont know what lenses to look for in this area. I dont want to spend a whole lot, so a couple $100 wouldnt be bad. I was looking on Amazon and found these mirror lenses: [ame="http://www.amazon.com/Opteka-Telephoto-Mirror-Digital-Cameras/dp/B0022VFDRK/ref=sr_1_1?ie=UTF8&s=electronics&qid=1267637113&sr=8-1"]Amazon.com: Opteka 500mm f/6.3 Telephoto Mirror Lens for Canon EOS Digital SLR Cameras: Electronics[/ame] [ame="http://www.amazon.com/Rokinon-1000mm-Mirror-Canon-Mount/dp/B001V97ISG/ref=sr_1_15?ie=UTF8&s=electronics&qid=1267637113&sr=8-15"]Amazon.com: Rokinon 500/1000mm F6.3 Mirror Lens for Canon EOS Mount: Electronics[/ame] So are any of these a viable option, or do i need to look elsewhere? I want nice images, so if these are crap then ill just be on my way. What do you guys use, or recommend?