I've found that all of my cloth shuttered Pentax bodies will respond to the "Pentax-Flick"... tested on the SV, Sa1, Spotmatic II, KX, KM, K1000, MX.
Originally posted by asaru The DIY mirror-lockup by flicking the shutter button has been discussed a thousand times. My post is not about that. I can make my MX do it without fail, but as I understand it, the ability of a given MX to do MLU depends on the exact angle at which the upper half of the shutter actuating assembly has been screwed tight. This clearly makes the finger-flick an unsatisfactory universal method.
The required action to accomplish having the mirror release first and not the shutter is to have an arm that reaches under the front panel where the timer is at. The rod that fires the shutter is not the same as the what fires the mirror... from above it to fire the mirror. What usually happens is not actually that complicated... I would think a lever could be installed that would perform the same way as by trigger with the OEM internal lever.