Manufactured by Bausch & Lomb Rochester between 1907-1910 under license from Friederich Deckel München. The shutter was originally introduced in 1903.
Mechanical leave shutter. Exposure times are controlled by a dial which on its turn controls a pneumatic retarder.
Flat dial with markings on face. Dial disk connected to the pneumatic retarder.
As from the 1910 model, the speed dial became a conic section with markings on the edge.
The right photo shows the Compur shutter.
The Compur appeared in 1912 as the successor of the Compound. Unlike the Compound which is equipped with a piston and cylinder pneumatic device, the Compur has a geared slow speed governor.
The most prominent device of the compound shutter is the horizontally placed cylinder on top of the shutter. The cylinder is partly hidden behind an interesting looking exposure speed setting dial.
When the selector on the bottom of the shutter has been set on M, the exposure time can be set by turning speed setting dial until the desired expose time appears under the arrow.
You may now press down the shutter cocking lever as far as it will go, otherwise the lever does not return to the initial position, indicating that the shutter has not been fully cocked.
When the shutter release is pressed the shutter opens and air in the cylinder is gradually released, letting the piston move; it closes the shutter again when it reaches the end of its travel.
Opening the shutter blades is done by the piston which moves from right to the left.
Travel time depends on how far the piston has been brought to the right. This has been set by a eccentric cam inside the disc while choosing the exposure time. The shorter the piston has to travel, the faster the exposure time.
Unfortunately, these fast exposure times are very sensitive. The cylinder air escapement or retarder pump is not as reliable than the mechanical clockwork escapement of the later invented Compur shutters.
Photo 1 Photo 2
Cylinder and piston serving as a retarder. The friction slows down the shutter movement.
Photo 2 shows the situation when the cam (in cocked position) holds the piston guide arm ready for exposure at position 1/10 second. Photo 3
Compound shutter with removed cover,
In released position. After shutter has been fired.
(1) Piston not visible inside the black cylinder.
(1a) Spring providing pressure on the piston guide arm.
(1b) notch hold the guide arm under pressure until the release has been tripped.
(2) cocking mechanism. When pressed down clockwise, the spring is loaded.
(3) Notch controls selector for M, B or T positions
(3a) Triggers the blade pin and thus opening the shutter blades when released by cocking mechanism.
(3b) Notch in M position giving way to trigger mechanism.
(4) Position to block trigger for B or T
(5+7 ) Notch to block trigger for B or T
(8) release arm for B and T.
(9) Pump or Bulb release air cylinder.
(10) Finger release lever.
Jo Lommen Cameras