Quote Originally Posted by polyglot View Post
Absolutely you can calibrate it out with a feedback system.
You don't need feedback. The warm-up/cool-down behavior of an incandescent bulb is repeatable, you just need to find the correction time. Then have the timer add/subtract it from the exposure time. It only takes a few minutes to run the test described in the application note. Of course, there aren't many timers that have a correction feature. I'm sure you can add the feature to yours.

The issue of timer repeatability has nothing to do with the warm/cool issue but with timer problems being ascribed to paper intermittency effects.

If the timer is repeatable, and the warm/cool time is corrected then suddenly all the 'intermittency' effects vanish.