dslr - Does shooting in "live view" also act as "mirror lockup"?

(If the musings below distract from the question, just read the title to understand what my question is.)

I'm interested specifically in the Canon 70D, but it would be interesting to know what the spectrum of behavior is among different brands and models.

I was just reading "Use a sturdy tripod and cable release. If your SLR has a mirror lock, use it. Camera shake can degrade the results."

I was using live view to give most accurate focus and easily point to the spot I want focused, and live view takes place with the mirror up.

I would think that the exposure can be done this way, but I wonder... does it drop the mirror just to lift it again, as an unchanging sequence of mechanical actions? Does the shutter even use a "motor" or is it driven by something more exotic?

(Long ago, I recall reading in a product brocure how a particular camera was ligher by using fewer separate motors. Old SLRs were run from springs (possibly cocked with the motor) and interlocked to work in a particular manner with mechanical rods and cams)

All I can tell from looking at the camera in operation is that I can't notice a light flicker in the viewfinder. But that doesn't proove anything.

IAC, does it really matter? Tripods are sold by weight of of camera+kit to be held steady, and there is no rating for how much a camera shakes itself during operation. I would think that SLR's are fairly standard in how much momentum they expell, and support equipment is built to handle that or it would be noticed. dSLRs have more resolution and people can zoom in and see the indivual pixels, so maybe the traditional standard of steadyness is detectibly lax now.

Answer

The short answer is yes, using live view is the equivalent from a mirror movement point of view as using mirror lock-up. (The mirror doesn't drop again).

However in the normal live view case the shutter curtain must reset before the exposure can begin. This results in one more mechanical action than just using mirror lock-up and not live view.

Additionally on many camera's (including your 70D) you can use electronic first curtain shutter (EFCS) when in live view. This reduces the vibration even further by only actuating the mechanical shutter at the end of the exposure. On Canon camera's this is normally called "Silent Mode 1" in live view.

In-camera vibration can be a concern for sharpness and is generally most visible at certain shutter speeds and/or orientations. The tripod/support system generally does not have a huge impact on damping in-camera vibration. i.e. even on very good tripods you can still measure the effects.

Of course whether you feel this is important to your photography is whole other (very subjective) story, ultimate sharpness is not necessarily what makes great images.

Some further reading:

http://krebsmicro.com/Canon_EFSC/index.html

http://blog.kasson.com/?p=6731

http://blog.kasson.com/?p=5402