We just purchased a 5mm f/1.8 lens from Amazon, and we love it. My previous lens experience gets cut short at a aperture of 3.5, and I really did not know what I was missing. Performance is great for indoor shots in low light. With one light on in the room, I was able to take a hand held shot with an ISO of 800 and a fast enough shutter to get a sharp picture.

Our RebelXT has a smaller then full frame sensor, which creates a lens focal length multiplier of 1.6. This is a bit inconvenient, as our new 50mm lens performs like an 80mm lens. Buying a wide angle lens with a decent aperture turns out to be quite expensive, so we don't have much.

Someday, we will replace our camera and get a full frame sensor, but in the meantime, we'll have plenty of fun.