I am looking at this remote for my Canon Powershot A640: http://www.bhphotovideo.com/bnh/con...s&Q=&sku=212477&is=REG&addedTroughType=search Does anyone have any experience with Powershot remotes? Is this the only one??? Any experience, tips, etc. would be great! I have ZERO experience with remotes for cameras of any kind. How exactly do they work? Thanks!