Does the Canon T3 have auto-focus in low light? I take a lot of photos after sunset with the lens open approx 3 - 4 sec. I have a Nikon D3100 and it does not auto-focus in low light. I've gotten some great images from my Canon Powershot that I've had for 6 years but I'm having trouble getting clear shots with the Nikon.
DSLRs do need some sort of contrast in order to focus. For example, DSLRs can have a hard time trying to focus on a white wall or a clear blue sky. Poor lighting can make this even worse. Try focusing on something that's far away like a tree.