Recently, a new generation of mirrorless cameras have hit the market. They look and work like S.L.R.'s -- interchangeable lenses, no shutter lag and so on -- but they're smaller and they capture high-definition video. (Since they're not technically S.L.R.'s anymore, Popular Photography magazine proposes the term I.L.C. for them, for "interchangeable-lens compacts." Let's run with it.)