Moonstone130 Loc: St Leonard, MD

When photographing star trails using the stacking method, is it useful to use mirror lock? I ask because my Canon 40 D will not shoot in continuous mode with the mirror locked. Continuous mode is apparently very useful according to several articles I have been reading.
Thanks!

Algol Loc: Georgia

I seldom use mirror lock and sometimes it shows, but then again 18mm shots do not have that problem, I photograph meteors and earth satellites. But if needed then another method is known as the hat trick. Set your camera in continuous mode and place a dark hat in front of the lens when it begins to open. After the vibrations die down (usually only a sec or so) remove the hat for the rest of the exposure. Problem is, you have to do this throughout your run so you can't just leave the camera and go have a snack or watch TV, lol.

Moonstone130 Loc: St Leonard, MD

Thanks very much. I will definitely try the hat trick!

roycebair Loc: Utah, USA

Mirror lock up is beneficial only when you have tripod exposures that are fairly short, i.e. in the 1/60 of a second to 1-second range. That's because the mirror "slap" vibrations occupy a large portion of that total exposure time. The major portion of these slap vibrations last about about a 1/4 of a second. Exposures longer than 1-second are much less affected by the vibrations, and you rarely see any improvement in sharpness with a mirror lock up.