Holy cow, 420-800? Yikes, what are you planning on shooting, the remnants of the LEM's base on the moon? Honestly, I wouldn't expect a whole lot from a lens like that. Most likely the quality isn't going to be there unless it cost over $10,000. I am not sure what that lens goes for but I can imagine that you can only use it with a tripod and do some astrophotography kind of stuff with it. You know the old saying about you get what you pay for. That is so true with camera lenses.
As for my camera, I used an old 300D Canon DSLR and an elcheapo kit 18-55mm kit lens for this one. You basically have to use a cable release and the Bulb setting or it is a pain in the ass to time the shot right. With a cable release you can control it better as opposed anticipating the shot using the shutter delay function in the camera, or pressing the shutter with your finger which will lead to a blurry shot.