Hey there, I'm new to the world of photography but RAPIDLY delving right into it all. I just got my SL1 (For a 12 pack of beer I might add) and a STM IS 18-55 kit lens. This is a fine lens for lots of things but I find myself aching to shoot astro photography. I have tried and gotten alright results with this lens, but my question is this: Can I use the EF 50mm lens on my SL1 with an APS-C sensor? Well I know it will fit, but will it not crop the image so something like an 80mm lens? I've read very confusing comments, some making it seem so and some not.