monopix
Cam repairer
I've never yet found a description of the way the double shutter on the Bessa cameras is constructed. All references seem to suggest it's a shutter with a double layer curtain. Stephen describes it as a 'Modified Copal shutter with two sets of blades' on his page here. Well I had the chance to dismantle a Bessa L recently and I can say this is definitely not a modified Copal shutter. In fact, it's two separate shutters with the main one (the rear one) being a standard Copal shutter as used in a trillion other cameras and not just ones made by Cosina. The second shutter, the front one, is completely separate and works, in principle, in the same way as a mirror does in an SLR - which makes sense because it's taking the place of the mirror in blocking light getting to the shutter.
The second shutter is built on to the back of a central box, very similar to the mirror box on an SLR, which has the lens mount attached to the front. The shutter is cocked separately and is linked to the main shutter using the same linkages as would be used to link the mirror and the shutter in an SLR. And the function is the same as a mirror in that, when the shutter release is pressed, the second shutter is triggered. As it fully opens, it triggers the main shutter which, in turn, triggers the second shutter to close after the exposure. This is identical to the sequence that takes place in an SLR between mirror and shutter.
It's actually a very neat way of achieving what was required.
The second shutter has no manufacturer's mark and I guess it's a Cosina design and they manufactured it.
bessa shutter 1 by Peter Robinson, on Flickr
bessa shutter 2 by Peter Robinson, on Flickr
The second shutter is built on to the back of a central box, very similar to the mirror box on an SLR, which has the lens mount attached to the front. The shutter is cocked separately and is linked to the main shutter using the same linkages as would be used to link the mirror and the shutter in an SLR. And the function is the same as a mirror in that, when the shutter release is pressed, the second shutter is triggered. As it fully opens, it triggers the main shutter which, in turn, triggers the second shutter to close after the exposure. This is identical to the sequence that takes place in an SLR between mirror and shutter.
It's actually a very neat way of achieving what was required.
The second shutter has no manufacturer's mark and I guess it's a Cosina design and they manufactured it.

