Originally posted by SunValley: Whenever I want to make sure mirror bounce won't ruin my moon eclipse shot I use the hat trick. Astrotracer On, Timed exposure Off, I hold a black hat in front of the lens, start the exposure with IR remote wait 3 seconds, remove the hat, start counting the Mississipis for the 2 to 15 s exposure time, put the black hat in front of the lens to stop the exposure and press the IR remote to close the shutter.
Yes. The shutter closing (which happens before the mirror comes down) can all by itself introduce some vibration. That's really only going to be a problem with telephoto shots but that's how a lot of people image lunar eclipses. (Although those wide angle shots showing the progress over hours as the moon arcs across the sky are cool too.)
BTW, this is a scenario where turning off timed-exposure mode in Astrotracer is advantageous. I had earlier asked for an example and you just provided it.