Modern Compur 0 shutter - maximum aperture opening adjustment ?

[Dave Tolcher]

Hi there, I have re-celled a modern compur 0 shutter (150mm symmar F5.6) with a 203mm Ektar from an slightly older and u/s compur 0. Moved aperture scale OK by leaving off the flash sync from the new shutter. I expected to find a small screw to re-site to allow the aperture to open fully but cant see anything obvious. Could someone provide me with a pointer on how to do it please.

Many thanks

Dave

[IanG]

The shutter that had the 150mm f5.6 Symmar will have a maximum aperture f7.59 with the 203mm cells. Well within tolerance.

Ian

[Dave Tolcher]

Prompted by Ian I have made an error - having just checked- quite right it was a synchro-compur with chrome ring.

It is identical to the modern compur except for the synch socket which is a single post on the synchro. The aperture scale is the same and screws right on once I removed the synch post. It is possible that I have made a bad assumption that because the aperture scales fit and in almost all respects the shutter is the same that the aperture mechanism is also the same. The scale at wide open points to F11 on the ektar scale rather than 5.6 on the symmar-s scale (assuming that 150mm was correct in the first place !). The aperture does not open fully at the moment which is why I thought it should open more (like the prontor shutters where you move a screw pin).

Obviously I would like also to adjust the other end to not go past F45.

[Peter Yeti]

Dave,

a picture of your shutter would help. But I'm afraid that your shutter is too old. As far as I know, the Synchro Compurs didn't have an adjustable diaphragm. At least mine don't. The next generation (black, w/o synchro in the name though with PC socket) have one or two screws to set the lever to the appropriate f-stop mark and one screw each to limit minimum and maximum opening. For maximum opening there are a number of threaded holes to pick from. This is the same as the Prontor prof. mechanism, at least in the latest Compur models.

Good luck,

Peter

[Dave Tolcher]

thanks Peter, the shutter I want to modify is the latest generation black compur 0. I haved modified several prontors but couldnt see the same mechanism.

Dave,

a picture of your shutter would help. But I'm afraid that your shutter is too old. As far as I know, the Synchro Compurs didn't have an adjustable diaphragm. At least mine don't. The next generation (black, w/o synchro in the name though with PC socket) have one or two screws to set the lever to the appropriate f-stop mark and one screw each to limit minimum and maximum opening. For maximum opening there are a number of threaded holes to pick from. This is the same as the Prontor prof. mechanism, at least in the latest Compur models.

Good luck,

Peter

[Peter Yeti]

Hmm, intersting... As I said, a picture would be very helpful. My shutters to compare with are all #1 and #3 Compurs. Could it be that this wasn't the same for the #0 version?

Peter

[Dave Tolcher]

Here you go:



I removed the 3 screws that release the aperture control ring. There is a small lug underneath that controls how far the aperture will open. It moved easily to open the aperture fully but I couldnt see how to adjust the positioning of the aperture ring on this lug to enable me to open the aperture fully.
Thanks again
Dave

[Peter Yeti]

Dave,

Thanks for the pictures. Apparently, this is still very close to the earlier Synchro Compur design, not much changed at all. The aperture is not adjustable, there's just one hole in the aperture control ring into which the pin goes that turns the ring holding the leaves. The limiters for min/max aperture are two rivets, which can be placed into different holes. I marked them in red on your picture. You obviously found out already that the three screws I marked blue release the control ring.



It might require some precision mechanics skills to change the limits since it is riveted. Anyway, the rivet on the right hand side (across from the pin) limits your max aperture since it is in the second hole. If it was in the first, the blades would open all the way. The rivet close to the pin limits your min opening.

Hope this helps somewhat,

Peter

[Dave Tolcher]

Peter, that is a perfect answer and very helpful. I will probably just remove the rivet for maximum aperture and not worry about minimum.

Best regards

Dave

Dave,

Thanks for the pictures. Apparently, this is still very close to the earlier Synchro Compur design, not much changed at all. The aperture is not adjustable, there's just one hole in the aperture control ring into which the pin goes that turns the ring holding the leaves. The limiters for min/max aperture are two rivets, which can be placed into different holes. I marked them in red on your picture. You obviously found out already that the three screws I marked blue release the control ring.



It might require some precision mechanics skills to change the limits since it is riveted. Anyway, the rivet on the right hand side (across from the pin) limits your max aperture since it is in the second hole. If it was in the first, the blades would open all the way. The rivet close to the pin limits your min opening.

Hope this helps somewhat,

Peter

[Dave Tolcher]

Of course, I could just move the aperture ring from the old shutter ! Doh....