You can get away with quite a lot. On another forum, someone posted an image and asked if anyone thought anything was wrong with it. A bit further down, he posted a picture of the front of the lens he took it with.... together with the smashed polarising filter which was fitted at the time.

There were no signs of anything wrong in the actual image.

Therefore, a few scratches or even air bubbles are not going to have much of an effect.


Steve.