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FWIW, I have noticed that even the 2 sec delay on my Pentax *ist DS is an insufficient time delay for the mirror slap vibrations to die down to the extent that image quality does not suffer. One night, I performed some ad hoc tests on bright stars which consistently showed “double stars” or signs of smearing and found that I was only able to obtain non-vibration affected shots using a minimum of 10 secs as a delay (by covering the front of the OTA and counting 1001, 1002, 1003….etc).
I haven’t tried the same (rough) experiment using our Canon 40D as it does have a genuine mirror lock up. Even though the 40D has a less mechanically violent mirror up/mirror down action than the Pentax, with both up/down actions controlled by some form of piston rather than spring, I still use MLU on the Canon.
Cheers
Dennis
Last edited by Dennis; 12-05-2008 at 12:43 PM.
Reason: Tested on bright stars, not as incorrectly written, the Moon
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