Target ADU for DSLR flats

I’m using a Canon T2i (550D) for imaging. In the flats wizard, what should the target mean ADU be?

Thanks,
Chris

The ‘very old’ rule of thumb is whatever time gets your histogram roughly 1/3 to 1/2. It’ll vary throughout the dawn/dusk as the sun rises/goes down.

I’d suggest doing your times manually using that method as I read through your thread on Astronomy Forum. Or, maybe it’s calculating it wrong?

http://www.astronomyforum.net/astro-imaging-forum/188362-flats-dslr-ha-filter-what-mean-adu-value.html

In case someone wants to read it.