Cap size?

[jrstark]

My Powershot A630 takes 52mm lenses and filters. If I leave just the adaptor and filters on, what size cap should I buy? My telephoto is 62 mm on the outside according to the box it came in, but the cap is 64. So do I need a 54 cap for the filters?

[Jon]

If you get a slip-on cap, yes. But if you get a snap-on cap, which has tabs that clip to the front threads, you'd use 52 mm. Most people prefer to not use the slip-ons since they also slip off and get lost.