I know some had just basic tube-sights, but a number did have some kind of optic. I get the impression most were removed and standard sights were used. It was a tool that didn't work well due to vibrations and other things that made it hard to use.
Ever look through a telescope that's not on a good mount? Trying to pick out some detail on something is hard if it's not a perfectly steady view. I imagine that's why it was pretty useless on fighter planes.