Luckily, I was able to make side-by-side comparisons, as I had both the 45mm and the 50 1.8. I'm not saying it's a huge difference that the average person would notice, but I don't think I would believe the reviews that says this 45mm boutique lens is the sharpest ever tested. For a 35mm camera, I would much rather have the extra stop or so, and certainly, for about the same price, I would pick the 50/1.4 any day, both for the extra aperture and for the more practical size (in my opinion).