I have been fiddling with time-lapse photography for a while. A motion-sensing app called
motion meets my needs (wildlife) far better.
motion monitors the webcam(s) for changes in the image, using very little cpu, and begins filming when it detects motion. Since I'm pretty happy with it and it took me a while to discover, I advertise it here as a tip.

It's in the repos for MX and antiX.
The threshold of change, time to film, frames per second etc. can be configured in a well-remarked file, /etc/motion/motion.conf. Since the file is so long, I found it helpful for my basic purposes to move some settings to the beginning so as not to have to hunt for them. The modified file is attached in case it's useful to someone as a starting point.
motion.conf.gz
https://motion-project.github.io
http://forum.mxlinux.org/viewtopic.php?f=94&t=44939
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