How important is mirror lockup when using slow shutter speeds? Was this an option or did all 67s have this after a certain date?

-- Pat Gerlach (patgbek@bekel.com), September 16, 2001

Answers

Using MLU at slow shutter speeds is very important. Not using MLU, the vib from the mirror has not attenuated enough when the shutter opens at slow speeds to allow for a sharp picture. In many cases, the left side of the frame will be soft and gradually sharpen as you move to the right side. The mirror vib will have ended by the time the shutter has finally closed. This can be seen when handholding the 150mm (and others)at 1/30 sec without MLU. The delay between the mirror locking and the shutter opening is an important feature(MLU) of this camera.

I believe that none of the Honeywell Pentaxs had MLU and that it was started shortly after the beginning of the Asahi. I'm not 100% sure of this however. I've never heard of MLU being an option.

-- Steve Rasmussen (srasmuss@flash.net), September 16, 2001.

I have and older Honeywell 6x7 with the MLU and a newer Asahi 67 without it. I assumed when I bought the 67 it would have this feature but it doesn't. I'd like some more info on this as well.

-- Ben Hughes (ben@hughesbros.com), November 29, 2001.

Depends on what you mean by slow shutter speeds; at roughly 1/60 sec. down to 1 sec. I feel it's mandatory, slower than that the shutter is open so long in relation to the vibration that it does not effect the exposure. However, I am so accustomed to using MLU that it's automatic. The first generation of 6X7, 1969-1974, did not have MLU after that it was a standard feature.

-- Arden Sampsel (marmutz@earthlink.net), December 01, 2001.