RB67 min shutter speed ona tripod without MLU?

[flavio81]

I will give this -- when I first got my RB67, I was surprised how smooth the mirror/shutter action was, but I just chalked it up to the non-instant mirror return. There'd be roughly twice the impulse (felt in the hands, not visible by the shutter) if the mirror returned as soon as the shutter was reclosed -- but there'd be no point in doing so, since the shutter will stay closed until cocked again.

I have a 35mm SLR (and older Praktica) with a mirror that returns only on advance, and my first SLR (Exa II) did the same. There's less felt movement, but it doesn't make any real difference in motion blur -- the return is after the shutter caps, after all. Apparently the RB was built with additional mechanics to help in this. Probably explains why I can hand hold it at reasonable speeds, even with the 250mm mounted.

In focal plane cameras, a big amount of the vibration can also come from the shutter. That's why mirror lockup isn't a panacea.

Worst case: Pentax P67. The shutter itself has horrible vibrations. I sold mine because of it. I've seen that the people who use the P67 (6x7) and don't complain about blur often are the ones who use the huge, ridiculous wooden grip handle, undoubtedly design to hold the damn machine steady while the big FP shutter makes its move.

It's sad really. Extremely sharp lenses coupled with a brutal shutter.