USM Stupid Noobie question

What is the difference in using a Canon EF50 f1.8 and a USM version? Apart from price and am I right in thinking the USM is just the auto focus..... so easier for a complete novice like myself?

The USM version (the 50mm 1.4) is a better built lens which has a faster maximum aperture (f/1.4 as opposed to f/1.8) and more accurate and faster AF. The IQ is pretty similar, imho, I've had both and they were both darn good. Oh, and you have full-time manual focus with the 1.4, which you don't on the 1.8. And the 1.4 has a real focus ring.

To me the 50mm 1.4 was worth the extra money. The iffy focusing and difficult manual focusing along with the wider aperture/build quality are worth it to me.

1.4 got better bokeh aswell