I sometimes use the 2 second MLU delay for normal work but haven't tested it.
Hi Doug,
I think you mean the self timer exposure delay of 2 seconds? In my testing of other cameras, a 4 second delay after the mirror slap would more or less allow all vibrations to decay to insignificant levels, but then the shutter release adds its own vibration which will impact image resolution.
I was trying to separate out the Mirror slap from the shutter induced vibration.
Yes, very much appreciated since this is usually poorly documented, but of high importance for high resolution cameras. In fact, adding the shutter release vibration to the not yet decayed mirror vibration might even cause an amplification if the amplitudes are in phase. So to find out the best combination of timings, one would need to add a timing component to the test.
The 5DS (R) offers a new adjustable shutter-release time lag for Mirror Lockup shooting, but the maximum delay is 1 second.
Therefore, I'd see it more as a handheld shooting feature (not for action shooting though) and to a lesser extend effective for tripod use (although it might help to avoid the in-phase amplification). If you can time and measure the vibration decay, it will probably show the requirement for a 2-4 second delay to be really effective.
I use a separate
vibration logger which has modest weight/mass of itself, and it allows to record acceleration data at a high enough sampling frequency (user definable up to 512 Hz) to make sense for most of the exposure times we would be interested in. I have a previous version which is slightly slower (320 Hz), but it already shows a few vibration swings within a second, even when used on a heavy tripod without center column extension on a concrete floor. My 1Ds Mark III allows a 16 second shutter release delay, so I can isolate both impulses.
Just offhand I would say the 2 second delay gets rid of the large majority of the mirror induced motion except on very long, heavy lenses that can take longer for vibration to die down.
I don't have a 5DS (R) to test, but my 1DS Mark III (a heavier body but with older mirror technology) requires more than 2 seconds to get rid of measurable vibrations. The complexity then becomes, how the remaining vibration translates to image shake, which additionally varies with the lens used and the projected image magnification factor. But anyway, if there is no measurable vibration, there can be no visible vibration blur during exposure.
So your test is very useful for assessing the image effect, but it is an aggregate that is accumulated during the actual exposure time. It would require an acceleration sensor, or a flying spot on a scope or something like that, to gain insight as to which time delay is minimally required to avoid (most of the) vibration.
Cheers,
Bart