Compur Shutters
The Compur shutters are still in widespread use. The most popular sizes are #0 and #1. Scroll down this page for a table of sizes. The earliest versions have three blades which open and close to deliver the exposure. The vast majority of these are #0 and #1 size, although there are a few #00 size. Most have no flash synch; these are obsolete, as a practical matter. However since they are of the usual rimset design they look similar to the later versions.
Later versions are called “Synchro Compur” or, in the case of the non flash version “Compur Rapid” and have five blades. These are also common in the tiny #00 size as well as the #0 and #1. Like the earlier models they use the tension type mainspring. The larger one in the picture is a special version of the same shutter made for Linhof.
The latest version of the Synchro Compur began production in the early 1970’s and is still in limited production. It has a new design torsion type mainspring and was originally available in sizes #00, #0, #1 and #3. Here, I show the #1 in the largely unsuccessful battery timed “electronic” version. Most of the electronic versions don’t work. Battery vendors for the PX 21 can be found via a Google search.
In addition to the usual #00, #0, #1 and #3 sizes there is an elusive size referred to by default as #2. There are variants and versions that make this a difficult size. These are usually four bladed shutters and exist in both dial set and later as rim set versions. They work more like the Compound shutters but are called Compur and were made thru the late sixties. This size (and the #00 size) is no longer available and replacement with new shutters is a problem. Repair of these an option which must be considered. #0, #1 and #3 sizes are readily replaced with new shutters, so the option of replace instead of repair is available. The Compur shutters are nicely made and well designed. They make use of more machined parts and fewer die stampings and therefore were more expensive to make and sell and have a reputation for high quality. The latest versions are perfect in operation and if it were not for their very high price would be popular. The earlier versions are OK but their performance does not equal their current Japanese made replacements.
| #00 | #0 | #1 | #2* | #3 | |
|---|---|---|---|---|---|
| body Ø | 45.2 | 58 | 70.5 | 80.5 | *** |
| front lens thread | M22.5-0.5 | M29.5-0.5 | M40-0.75 | M45.75-0.75 | M58-0.75 |
| back lens thread | M22.5-0.5 | M29.5-0.5 | M36-0.75 | M45.75-0.75 | M58-0.75 |
| overall thickness | 16 | 20 | 20 | 26.75 | 26.75 |
| front to iris | 9.3 | 10.2 | 10.75 | 14.5 | 31.5 |
| mount flange thread | M25.0-0.5 | M32.5-0.5 | M39-0.75 | M50-0.9 | M62-0.75 |
| lensboard hole Ø | 26.3 | 34.6 | 41.6 | 52.5 | 65 |
| iris Ø (Max) | 17.4 | 24 | 30 | 35 | *** |
Self Timer Operation
“P” Press Focus Type and Self Timer Type(No Press Focus)
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.
Operation of Compur 1 Shutter
The five blade Synchro Compur #1 is probably the most numerous of all the Compur shutters. It features shutter speeds from 1/400 Second to One second as well as “B” and “T” Speeds are selected by turning the knurled outside speed dial. There is an additional spring engaged when setting the shutter to 1/400 second. This takes a fair amount of force to turn to 1/400 second and may be very difficult to set to the highest speed with the shutter cocked. This is normal operation.
The shutter is released by operating the release lever or using a cable release in the release socket.
The Green “M/X” lever sets the flash contacts to be used with electronic flash or flashbulbs. Normal flash setting for modern electronic flash is “X”
The Synchro Compur # 1 has both the self timer and press focus.
The #1 shutter has both self timer and press focus. The square stamped lever/button can be used to open the blades when the shutter is cocked. The round button to the right operates the self timer. (Set the cocking lever then push the button, this allows the cocking lever to move a little more and engage the self timer. above. The two controls operate independently of one another. The blades should open when the press focus lever is pushed in and close crisply when the lever is pulled back out. It is a common fault/defect that the blades stick open and do not snap shut when the lever is pulled back out. Even in the case of defect, the blades will usually close if the shutter release is operated.
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