Old brass shutter

[Petzval Paul]

Hi everyone,

I have an old lens that is mounted in a B&L twin-piston shutter. It's a bit similar to the Unicom ones which seem common enough, but it lacks the aperture scale along the bottom and instead the aperture dial is mounted behind the shutter-speed wheel at the top (making two wheels, one behind the other). Not sure what the name of this shutter could be and I have looked everywhere with no success.

The problem is that the shutter is dead. The first question I have is simply: is it worth it to try and fix this old bad boy? I only shoot collodion so I really don't need the shutter, but it would be nice to have it working, so at least I can use it on bulb for the long exposures. Alternatively, were these old shutters made so that the sizes were somewhat standardized? IOW, could I find a replacement shutter (preferably non-pneumatic) that would fit the same threading of my lens?

Thanks,

Paul

[Archphoto]

Is it worth it ? In my opinion YES

One the other hand: how much do you want for it (as is ) ?
I recently got a full plate camera for free her that needs a shutter.......

Peter

[Darren Kruger]

IOW, could I find a replacement shutter (preferably non-pneumatic) that would fit the same threading of my lens?

There is a small chance there is a more modern shutter that would work. What are the thread measurements for the lens from the shutter? How thick is the shutter where the cells screw in?

More than likely you would need to get some adapters made to get the cells to fit a more modern shutter.

-Darren

[GPS]

These shutters, if not missing parts, are not difficult to be repaired. But when it comes to precision they are almost good for nothing. Their speeds are not reliable and can vary a lot on the same shutter speed because of a faulty mechanical construction.
If your shutter is not working at all it's probably because of a misaligned disk with shutter speeds (= violent treatment or a loosen screw).

[Wimpler]

These shutters are beautiful things. Since they are simple to repair, it is definately worth it. Especially because it will be extremely expensive to mount into a new shutter, if at all possible. The old shutters were not standardized at all. Stick to this one!

While not easy to get them to run precise, when cleaned they will definately run acceptible consistent, which is good enough for most uses.

The main parts that need to be cleaned are the shutter selector speed, and the two pistons. On some shutters these can be removed and cleaned without actually opening the shutter. On others, the cover needs to be taken off but no internal parts need to be disturbed.

If you wish, I can go take a look at a shutter I may have lying around and give you more precise information.

[GPS]

The slightest mutual misalignment of the two cylinders (cleaned or not) used to delay the shutter action (the cylinders on the right if you face the lens) can cause huge difference in the shutter timing. The misalignment can happen inadvertently just touching the bottom cylinder in the "wrong" way. There is no way to know when the misalignment happens...

[GPS]

Just to add - once I measured a Unicum shutter with my Calumet shutter tester. The shutter was entirely cleaned, working mechanically correctly. The times were - a joke. Inconsistent and changeable with the "wrong" touch on the cylinders. By the way, there is no way to keep their correct alignment firm, the construction is faulty.

[Wimpler]

In regular conditions, if you cock the shutter just before the exposure, there won't be a lot of forces working on the cylinders. Ofcourse, a lot more care needs to be taken then when compared to modern shutters. However, when properly used, I would be very surprised if one could not use them with a maximum error of a stop.

However, I've never done measurements over a long time or in non-ideal conditions. Lets just say that these shutters are an improvement over using lens caps or hats as a shutter

[CCHarrison]

You have a B&L Iris Diaphram Shutter patented in 1888. You can see the repair for this shutter here from Restoring Classic & Collectible Cameras By Thomas Tomosy:

http://books.google.com/books?id=0cQ...h+lomb+shutter

Here is the patent on this shutter http://www.google.com/patents?id=VGN...ad=0_1#PPA1,M1


Dan

[GPS]

In regular conditions, if you cock the shutter just before the exposure, there won't be a lot of forces working on the cylinders. Ofcourse, a lot more care needs to be taken then when compared to modern shutters. However, when properly used, I would be very surprised if one could not use them with a maximum error of a stop.

However, I've never done measurements over a long time or in non-ideal conditions. Lets just say that these shutters are an improvement over using lens caps or hats as a shutter

Of course you cock the shutter before releasing, no doubt about it. That's not the problem. The problem is the fact that a lateral (radial) touch on the cylinder in question makes it slightly turn around its pivot and changes its alignment with the corresponding cylinder. This touching can happen when you open the camera, when you clean the lens, when you change the aperture, when you remove the lens with its board and on many other occasions...
You can have many stops difference of the exposure time without even noticing you touched the thing! Yes, you can even stop the shutter functioning just by a slight, invisible misalignment of the cylinders! And that is only one problem of this construction, there are more of them. The manufacturer noticed the problems too and tried to make up for them but the construction didn't allow it with full success. When you understand the construction you can see why...

These shutters, although an improvement over a lens cap were unreliable already in their time and left as such as soon as a new construction (spring shutters) were available...