Originally posted by officiousbystander Thanks for this. I'll practice the single index finger technique. But I can't work out what you're doing with the mirror lockup.
@LensBeginner has it. That's about all there is to it. It works on the K1000 as well which also doesn't have a proper MLU. It takes less finesse than it looks.
You just "flick" the shutter release without actually pushing it - the mirror will go up but the rest of the shutter sequence won't complete and it'll remain that way until you actually press the shutter button to expose the image, and then the mirror comes back down normally, e.g. a little mirror lock-up hack for long exposure and what not.