Cleaning stuff with compressed air

I know everyone says it's a bad idea, but the idea that you shouldn't clean optics with compressed air seems to have been taken as read for a long time now. Most modern compressed air cans say "no residue" or something to that effect. If this is true, why is compressed air a problem? Or are the can manufacturers lying?


Evenif it's not good for the sensor, why is it not good for the lenses? I find my rocket air to be pretty puny to be honest, and dust seems to settle on lens elements half as quickly as I can blow it away. I'd much rather blast lenses with compressed air before giving them a proper polish.


I'd justlike a bit of a technical explanation - and besides, I think it's always worth questioning any accepted wisdomas most people seem to advise playing it safe and not use compressed air anywhere near an SLR.