OKAY so this lens is one of the CHEAPEST out there for Canon! It's a Prime lens, meaning that it is fixed at the focal length of 50 mm (no zoom in or out) and its aperture is very WIDE at maximum of 1.8!!
I HIGHLY recommend this lens for people who want to do more with their Canon, whether they just have a Rebel or even a full-frame more professional camera.
I have to admit I was frustrated with this lens on my previous Rebel T3i. My photos were never TACK sharp, even with a larger depth of field like f/3.2. In lower light, it just didn't work out that great - and I blamed it on the lens. So I was always afraid of using this lens at its widest (f 2.0 or f 1.8) because I thought it would NEVER be in focus
However, I took a leap with my NEW camera- the Canon 5D Mark III - and shot at f1.8!!!! On a portrait! Woooo. When I came home and popped the SD card in to check out the results- I was shocked! The photo was focused and sharp and everything I hoped!
50 mm f/1.8 1/400
50 mm f/2.0 , 1/400
So- it's a great lens on a great camera with a good sensor like the Mark III. Yay!