The 50mm f/1.4 lens is known to be a little subject to flare and artifacts (more so than the much more expensive 50mm f/1.2 L lens). This hood helps greatly to reduce such flare. I took some photos of my daughter putting decorations on the tree before Xmas - the tree lights caused some flare spots and ruined quite a few of them. After putting the new hood on, the flare spots nearly all vanished - removing the filter helped even more. My suggestion: get a hood before a filter (unless it's one of the very best filters, in which case more expensive than this hood). I shoot in a lot of low-light situations, often with point sources of light (concerts etc.) - in my own experience with the 50mm f/1.4, the hood without a filter is the best set-up. It offers lens protection and can be reversed for convenient storage. Usual Canon high build quality.