F3 in A with MLU

Went out for a stroll on Saturday and found a few things that I thought would make some good B&W shots. I had my camera on a tripod and it set to A mode. I figured that I would use the MLU to keep the camera completely still. However the camera fired and then locked up. I figured that the camera was reading the scene through the stopped down aperture. I had to release the mirror to shut the shutter. So I went to manual mode and it worked like a charm. SO is the MLU just not usable in A mode or am I missing something.?

The manual says that "with the mirror locked up you should not operate the camera on automatic". If you need copy of the F3 manual send me a PM. cheers

I thought that was the case. Been a long time since I read the manual.

Oooh that's manuals are made for then...

I think you can do it but you have to lock the exposure in with the button, then keep it pressed while you lock up the mirror, then fire without removing your finger from the exposure lock button. PITA but it can be done, maybe if you have a few extra fingers handy.