Originally posted by Oddity96 i understand that but does it not just help with stay light in the picture and does not a good uv filter do the same thing? thank you for bearing with all these newb questions but i can't learn if i don't ask.
Here's an analogy, because I can't draw a diagram:
Screw a filter on there, and put the barrel of a pistol at angle, at the outer edge of the filter, touching it. Pull the trigger and the bullet pierces the filter and lens.
Now, put a hood on there and do the same thing, figuratively speaking. The "wall" of the hood, sticking out an inch, two inches, whatever, blocks that bullet from entering your lens.
And in this analogy, that bullet is actually light.
Filters have their function, but they still allow stray light to enter from the sides. "Good" light enters at a "good" angle and is good, but the bad light coming from the outer perimeter of your lens at extreme angles bounce around like crazy and screw up your image with bad flare and glare.