I’m happy to have stumbled across Axel Bauer’s isightcapture utility. It’s a quick little command-line app that can grab a frame from your camera, and do some basic sizing and file format manipulations.
If you drop by the archives of any home automation discussion group (such as the XTension list) you’ll find a lot of not-so-simple approaches to this seemingly basic task. While there are some fine webcam utilities for the Mac, if all you need is a simple snapshot, most of them are overkill. And it’s yet another app to have running, keep updated, and so on.
So I’ve been experimenting with using Bauer’s isightcapture, driven by a Python script periodically executed by XTension, to keep an eye on my dog while I’m out of the house. So far, so good.