I'm ready to get me a nice prime lense and have narrowed it down to the: Canon 50mm f/1.4 Canon 85mm f/1.8 The primary use of this lense will be for portrait; body and closeup. I've read a ton of reviews on these, but trust the 'reviews' of the forum a bit more. Which has the better image quality overall? Using a Rebel XTI, how much room would I need to take full body pics/portraits? I suspect that due to the 1.6 crop, I would have to be backed up, but don't know how much? Image Quality is my number one priority for this lens. thx in advance for your advice.