Here's what you'll need:
- some 800 grit sandpaper
- some 2000 grit wet/dry sandpaper
- some sort of plastic or metal polish - I used Mother's Clear Coat Wheel Polish, because it was what I had handy in the garage.
Here's the procedure:
(1) Go over the surface of the lens thoroughly with the 800 grit sandpaper. I just used a rubber sanding block, so I did this all by hand, and probably spent about 10min on this step. I'd sand in one direction, then turn 90deg and sand that way for a couple minutes, then go over everything again at a different angle, etc. If you have a palm-grip electric sander you could do this stage quite a bit faster. If your lenses are really heavily pitted, you could probably start with a slightly more aggressive sandpaper, say 400 or 600, then work on to the 800, then continue with the rest of the procedure.
(2) Wet sand the lens using the 2000 grit wet/dry sandpaper. For those who don't know what wet sanding is, basically it's just sanding with the sandpaper and the surface being sanded fully wet. That way the particulates you create get washed away, so the paper doesn't get clogged up as fast, and you're not grinding the dust into the smooth surface you're creating.
Wet sanding must be done by hand! Don't use the palm grip electric sander to do this!
To start, just tear off about a 5x5" square of 2000 grit sandpaper and soak it in water. Also splash some water on the lens. Start sanding away, just use your hand (no sanding block), and go in a nice, circular motion. Keep the sandpaper fully wet - I just keep the tap water on at a low rate and dunked the paper under every 15 or 20 seconds probably. I wet sanded the lens for probably 5min or so.
(3) Use the plastic or metal polish to polish the surface a couple times. Very simple, just follow the directions on the bottle of whatever you're using. I think Meguiar's actually makes a product that is intended for polishing plastic lenses, bumpers, etc. I used the wheel polish, I'm sure a car polish would work fine, too. I did a couple applications.