Operation of Compur Self Timers and Press Focus Features

S.K. GRIMES
Services for the Large Format Photographer

Operation of #0 Compur Self Timer or Press Focus

"P" Press Focus Type Self Timer Type(No Press Focus)

Some #0 Synchro Compur shutters came with a Self Timer feature.
The self timer button has a stop (see arrow) to keep the cocking lever from moving past that point in ordinary non-self timer use.

After the self timer button has been moved, the shutter cocking lever can be moved as far as the arrow indicates. This engages the gear mechanism needed to cause the approximate ten to fifteen second delay after the shutter release is operated until shutter clicks at its set speed.

The Press focus version Compur P looks the same except that the button pictured is used to operate the Press Focus Feature. Press Focus allows the photographer to open the shutter blades and view the composed image on the ground glass without having to disturb the shutter speed setting or otherwise operate the shutter.

To view the composed image on the ground glass, cock the shutter at any speed setting then push the press focus button back and operate the shutter release. The shutter operation will be blocked with the blades open. To close the blades prior to inserting the film holder re-cock the shutter. This will also push the press focus button back to its rest position.

So why are there two different versions?

The small sized #0 shutters were used on both folding rollfilm cameras (permanently installed shutter) as well as on small sized view cameras. Press focus on a camera without a viewback will cause problems when it is operated since it will spoil the film and have no usefulness at all on such a camera. Rather than design a separate casting the makers used the same parts to operate a nice to have self timer on these mostly amateur cameras.

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