On a Canon 50D or 5D I wish to trigger the shutter automatically when the camera senses something has come into focus. Specifically:

- Put the lens in manual focus.

- Use manual focus to focus to a depth with nothing currently in it.

- Now hold the button halfway and wait.

- When something moves into focus field you get a beep and a red outline on the focus box.

I want to take a picture triggered on that event.

I could use a triggertrap with the audio sensor, and once triggertraps are available again I will get one and try this. There must be other ways to do this also, and I would be interested in other solutions.

Thanks, SD