Thank youpop the front cover off with a small flathead screwdriver, remove 4 philips screws, front comes off exposing lens. scrape glue off to unscrew lens, replace with new lens and screw it in till focused the way you like, then re-glue (with superglue or bondic) so it doesn't move again, re-assemble. easy-peazy... as for which lens, the stock 2.8 gives you a very wide FOV ~110degrees, 4mm a bit less maybe 90', 6mm a bit less yet, perhaps 70'... depends on what you need.