When selling or buying a used camera, one important piece of information you want to know is how many shutter actuation’s are on the camera. The Canon 40D is rated for 100,000 actuation’s, which means buying a camera with 90,000 would be a bad idea unless it’s really cheap. If you want to check your camera, David at astrojargon as created a utility: http://astrojargon.net/40DShutterCount.aspx. There is both a Windows and Mac version, but it only works with a limited range of cameras:
This works on any of the Canon DIGIC III/IV DSLRs except the 1D* series. This means it will work for the 40D, the 50D, the 450D, the 500D, and the 1000D.
