OK, this may seem like an silly question to some, but here goes. On the many of the point and shoot cameras the specs on the lens are listed such as "5.0-100.0mm f/2.8-5.7 (35mm film equivalent: 28-560mm)" for the Canon SX1 IS. While I'm pretty sure I understand the conversion to 35mm equivalent, I haven't heard much about the f range. f2.8 at 28mm sounds pretty fast for such a small lens, and f5.7 at 560mm sounds great, but is that true. To do that on a DSLR with a full frame or 1.6 sensor would take a monster lens. While I'm sure the picture quality is very different, is the ability of the P&S lens to gather light, really the same as that on a "real" camera? I keep think there should be something like a "35mm equivalent" for this information as well?