Is This a Shutter for the Front of a Barrel Lens?

[Steve Smith]

I found this in a box of stuff I was given:



I think it is a shutter which fits on the front of a barrel lens.

It has three settings:

O - Permanently open for focusing.
Z - Same as B i.e. shutter open whilst cable release is pressed.
M - A fixed time release.

In the M setting a fast press of the cable release gives a consistent open time of about 1/30 (rough guess). If the release is pressed slowly the blades will open slowly then snap shut.

(the blades are shown half open in the picture intentionally with the control set half way between M and O).

Can anyone tell me anything about this? Make, age, etc.


Steve.

 

[Dan Fromm]

Steve, shutters made to be mounted in front of a lens in barrel typically have three radial set screws 120 degrees apart that hold the shutter to the barrel. You showed only one side of your wee beastie. Does it have three threaded holes in the side 120 degrees apart? You showed just one side. Please show the other side, also give the dimensions.

 

[Steve Smith]

I will get another picture tomorrow.

However, it's about 100mm diameter with a recess in the back about 35mm diameter. There is only one screw to hold it to the lens.


Steve.

 

[paul_c5x4]

I also have a shutter (almost) the same - Mine is finished in a crinkly black and has three screws set at 120° radially. If you open it up, there is nothing in the way of a timing mechanism inside, just a spring to keep the blades closed.

 

[j-dogg]

I have been looking for something like this for a lovely Bausch & Lomb Zeiss-Tessar 1a barrel lens I acquired from a 5x8 Graflex.

 

[Steve Smith]

Mine is finished in a crinkly black and has three screws set at 120° radially. If you open it up, there is nothing in the way of a timing mechanism inside, just a spring to keep the blades closed.

Definitely just the one screw on mine.

The mechanism might be simple but I think it's fairly consistent if you push the release quickly.


Steve.

 

[paul_c5x4]

See: http://www.earlyphotography.co.uk/site/entry_S28.html

The one I have is virtually identical to the bottom of the three pictured.

 

[AgX]

In the M setting a fast press of the cable release gives a consistent open time of about 1/30 (rough guess). If the release is pressed slowly the blades will open slowly then snap shut.

Any idea how this is achieved?

 

[Steve Smith]

Any idea how this is achieved?

I think any consistency as down to how you press the release. in the web page Paul linked to, it suggested a shutter speed of 1/5 to 1/20 depending on cable release pressure.

Most of the travel of the cable release is taken up with opening the blades. Once the travel gets to about 90% the blades snap shut again. I think that if you press the release quickly you will be more consistent than trying to do it slowly.

I notice that the web page also suggests that shutter speeds up to five seconds can be achieved on the B setting. Not sure why they say that as you could keep it open forever.


Steve.

 

[AgX]

So I assume it is a matter of force:
Pushing slowly would enable one to stop at a threshhold at full-open and keep the shutter at this point.
Pushing beyond that threshhold would make the shutter snap and close at more or less fixed time.