Astrophotography and the Digital SLR

I've been taking astrophotographic pictures for a few months now, and while I'm certainly no expert, there are a few things I've learned. I'd like to share some of the insights I've had taking such pictures with my Nikon D200. Most of the advice should be translatable to any digital SLR. To begin with, yes, you can take good photos of astronomical objects with a digital SLR. But, no, you're not going to get closeups of planets with such a setup. The longest lens you're likely to have is a slow 500mm. Not accounting for any crop factor your camera might have, that's only a 10x magnification. Most planetary observers use telescopes in the 20x to 30x range. That would be equivalent to a 1,000mm to 1,500mm lens!