Originally posted by Thomas The above method does use battery power. Here's a technique I used years ago before I had a 67II. (lited from a p-net thread)
"I did a search for long exposure techniques with the 67; none I found was really straightforward. The following procedure worked for a 3 hour exposure using a Pentax 67 without exhausting the battery: 1. Focus a tripod-mounted 67 and advance the film and lock up the mirror. 2. Remove the battery. 3. Have the shutter speed set a "B" and depress the shutter.
The shutter will not close until the battery is returned. Most tripods will will require removing the camera from the tripod and QR plate to remove the battery and since the mirror is up, the compostion can't be checked upon remounting the camera. Not really a problem for wide angle shots, but could be with long lenses."
NB If I remember correctly this works with the shutter set between any 2 speeds, e.g. 100 and X.
Good luck
I believe this technique works for the 6x7 model. I tried it with a 67 and pulling the battery out closes the shutter and drops the mirror.
I made a device for use in astrophotography. It simply holds the safety button ( the recessed button below the shutter release) in while the extended exposure is made. Once this button is held in, you cock the shutter, operate the mirror up if desired first, then press the shutter release to open for the exposure. It does not matter what shutter speed you have selected and you should not have a battery in the camera for this to work.
The link below shows how I made a simple plate that temporarily attaches to the camera for this operation. I used a cable release to operate the safety switch and releasing the cable release to end the exposure.
A company named Hutech made one for years, but no longer makes them.
I've shot hundreds of hours with this setup and no battery!
http://www.cloudynights.com/ubbarchive/showflat.php?Cat=&Board=Film&Number=1...v=#Post1702165