Compur-Rapid lock open?

[shawn]

Anyone know an easily reversible method of locking open a Compur-Rapid shutter? I am adapting a Compur-Rapid with Ektar 47mm f2 lens to my Fuji and just want the shutter to always stay open.

I know I could open it all up and remove the shutter blades but wanted to know if there is a simpler method.

Thanks,

Shawn

 

[Dan Daniel]

The shutter blades are controlled by one ring. The ring has pins on it that each blade slots into. There is one pin that is longer and projects up into the interior. In this image which I took from this location-
https://simonhawketts.co.uk/wp-content/uploads/2017/05/compur_rapid_shutter_cleanup-20.jpg
I want to give proper credit) There is a large slotted screw a little above center of the image. It is the pivot point for a flat J-shaped metal piece. At left end of this J is a tab with a thin spring coming in from the left. Then as you go up the J is a tsb of metal pushed up, then a slot with a darker gray pin in it.

That J is what opens and closes the shutter blades by moving the gray pin back and forth. I don't know which size the photo is, but the idea is the same on the #00 and the #0.

You'll need to remove some parts, mainly the cocking ring, to get a clear view of this. Anyway, you could jam this part with the blades open. Check the cocking ring for how its connection to this piece reacts to it, etc. Well, hopefully this will get you going.

 

[Peter Jennings]

Why not just set it to B and then jam something behind the release lever so that it doesn't spring back?

 

[shawn]

You'll need to remove some parts, mainly the cocking ring, to get a clear view of this. Anyway, you could jam this part with the blades open. Check the cocking ring for how its connection to this piece reacts to it, etc. Well, hopefully this will get you going.

Thanks, very helpful. I wonder if removing that screw allows that actuator to be removed? If so I should be able to just take that out and then open the blades with the tab and leave it that way.

Shawn

 

[shawn]

Why not just set it to B and then jam something behind the release lever so that it doesn't spring back?

Any downside to leaving the shutter open on the B setting? Stress on springs or anything like that? While testing the lens I was using a rubber band to hold the shutter release down and the blades open.

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I also have a 50mm f2 Ultron lens I can try on this setup.

Shawn

 

[shawn]

I had a more beat up Syncro-Compur that came off a Vitessa. I opened it up and removed the main spring and then opened the shutter blades. The aperture is a little easier to adjust on this one too because of the LV system on it. Moved the Ektar lenses onto this shutter body and they focus fine here too. Will be fun to compare the Ektar and the Ultron.

Shawn

 

[Steve M.]

All of my cable releases have a knurled knob that you turn to lock a shutter open on B until you decide to release it.

 

[Greyscale]

Set it to B and use a locking cable release.

 

[Dan Daniel]

Any downside to leaving the shutter open on the B setting? Stress on springs or anything like that?

Shawn

No downsides. Even if so, what is the chance that the shutter will actually be needed again?

 

[shawn]

All of my cable releases have a knurled knob that you turn to lock a shutter open on B until you decide to release it.

There is no provision for a cable release on this shutter. If there was I would probably use a small screw turned down in it to lock it open.

Shawn

 

[shawn]

No downsides. Even if so, what is the chance that the shutter will actually be needed again?

Good point, probably fairly low.

Shawn

 

[johnnyrod]

Maybe you could modify the speed setting ring to turn the B setting into a T setting? Take a look here, although this shutter works on B and T without cocking - try some of the other albums perhaps.
www.flickr.com/photos/bikeguruuk/albums/72157669025971471

 

[Dan Daniel]

Thanks, very helpful. I wonder if removing that screw allows that actuator to be removed? If so I should be able to just take that out and then open the blades with the tab and leave it that way.

Shawn

Missed this earlier.

Yes, you can remove the actuator. But then the ring that opens and closes the shutter blades is loose and could get knocked around and close the blades or leave them partially open. It's hard to see in the photo. but that spring has slight kink in it that causes it to slide to one extreme or the other of the range of the actuator. As you slide the actuator open and closed you can feel the spring wanting to be at one position or the other, not in-between. I assume that this is partly to 'secure' the actuator in position, not only to provide a small push to the actuator's travel.