01-25-2011, 11:46 AM
No, you can't do 3 bracketed shots with one shutter release, with or without mirror lock up. Of course, mirror lock up requires time, else using mirror lock up would not make sense. Of course, it is possible that the scene changes a bit when shooting 3 images (your bird as example), but that should never be a problem, as you can edit that bird out before you merge the different exposures.
However, I sense there is a trick that might make life easier (faster) on you. The 400D has only one motor for driving both the shutter mechanism and the mirror movement. Moving the mirror is linked to the shutter. However, the 50D is different. It has two separate motor systems. In live view, the mirror goes up. While with the 400D the mirror needs to move up and down between shots, it does not have to with the 50D in live view. So, try setting up the 50D in live view with NO mirror lock up and WITH bracketed exposure. It should now be possible to make 3 consecutive shots in fast succession, each with a different exposure, and with no mirror induced vibration.
I can not test it, because I have no 40/50/60/7D at hand, but I have a hunch this might work for you. Still 3 shutter presses, but as fast as you can. And then just invest in a remote cable shutter release, so you will not induce vibrations via shutter button pressing. Success!
However, I sense there is a trick that might make life easier (faster) on you. The 400D has only one motor for driving both the shutter mechanism and the mirror movement. Moving the mirror is linked to the shutter. However, the 50D is different. It has two separate motor systems. In live view, the mirror goes up. While with the 400D the mirror needs to move up and down between shots, it does not have to with the 50D in live view. So, try setting up the 50D in live view with NO mirror lock up and WITH bracketed exposure. It should now be possible to make 3 consecutive shots in fast succession, each with a different exposure, and with no mirror induced vibration.
I can not test it, because I have no 40/50/60/7D at hand, but I have a hunch this might work for you. Still 3 shutter presses, but as fast as you can. And then just invest in a remote cable shutter release, so you will not induce vibrations via shutter button pressing. Success!