ive been experimenting with mirror lock up recently, and it got me thinking, i should probably do some tests!
...is mirror lock up just a battery waste?
...should you always use a remote shutter press for EVERYTHING? even hand held stuff if thats even possible ?
Mirror Lock-up - importance w/ & w/o IS (Link)

The question is periodically raised as to whether-or-not MLU is needed "with modern equipment". One must remember that "modern" is used to describe current equipment at any time in history. The suggestion has been made that MLU is "no longer important" through the years, more so since about the '70's - '80's, increasingly as makers began to NOT-include it as a standard feature, and wished to convince us to be satisfied with their judgement.
Numerous professionals have tested equipment to determine to their OWN satisfaction the truth about this function.
The consensus bottom-line has indicated that when one seeks the absolute best image quality which their equipment can deliver, ...MLU should be used, if possible/appropriate to the shooting situation.
There have been a few pooh-poohers, but one can read various articles on the web, and make a judgement as to which writers are to be considered most-authoritative. My own study puts me solidly in the "use it" camp.
A web search on mirror lock-up will turn up much discussion.
One of the most thorough analysis has been done by a respected German nature photographer, Fritz Polking, and can/should, IMO, be read at the following link.
Go to Home page > Workshop 1 > Sharp Photographs.
It is a long page, with many test results and comment (MLU, IS, etc.):
http://www.poelking.com/index_e.htmI have posted re. this link before. Apologies to those who find this info redundant.
HTH others,
Edit: There is also quite a bit of experienced and/or thoughtful discussion here:
http://photo.net/learn/nature/mluLarry