View Full Version : Quick Fix for some Focal Plane Shutters

Steven Tribe
8-Jul-2017, 04:03
I have had the misfortune to have been unable to resist buying a number of these innovative focal plane shutters from the period 1895 - 1930. The concept behind these was great, perfect for the growing "Enlightened amateur" market. They have no movements and only a few lenses available with focussing mounts for each model. Typical sizes were from 9x12 up to 13x18cm and originally were made by Goerz, but followed by ICA, Ernemann, Mentor and others. They were crtainly very useful in the era when other shutters were pretty unreliable as far as speed. Note that my comments do not apply to the Graphic Speed model.

In my experience, most of these are well past their useful age. The shutters I have locked at (Intimately!) have been worn and extremely complex. It doesn't help that diagrams showing moving parts are usually unavailable.

Recently, I purchased a lot which, apart from the two ULF plate holders I was after, contained a Goerz Ango set (camera, Celor, case and 5 DDS's). I eventially looked at the camera this week after. repairing the ULF plate holders.

For the first time, I found that the mechanics, as far as I could tell, were OK. The movement of the curtain was very sluggish. The curtain was full of micro cracks in the rubber (?) layer and small holes in conjunction with these cracks.

I had no confidence in my ability to sucessfully take the shutter apart and re-assemble. It stuck me that I could just replace the three sections of curtain which were important. Basically - cut away the 3 sections, but leaving a 1 centimeter wide edge at the two reels and crossbars in order to glue the new pieces in. The only real problems I could see were:

- would the old rubber base prove to be a suitable surface for glueing?
- could I do a piecemeal assembly ( 3 pieces of curtain, 6 separate edges to be glued)?

This last point is made more difficult as the bottom roller has to be under some tension in the "uncocked" position. This means the bottom roller has to be locked under the operation and that the cut and replace must start here at the bottom.

This what the sections look like.
The curtain is made up of two separate sections, held together by a very thin (silk) cord. One end of this cord is attached to a slider. This slider can be (with difficulty!) moved to positions 1 to 7. The slack in the chord can be moved around to widen/narrow the gap - thus decreasing/Increasing the speed. A simple operation, but best done at home, I think.

Steven Tribe
8-Jul-2017, 05:14
Cutting out the three sections is quite easy. I did this one section at a time, completing the repair before proceding to the next section.

I had the replacement curtain material from Micro Tools, Germany. This was bought over 5 years ago, whem there was a selection of qualities. They appear to have only one type and size for sale at present.
The material should be used in the correct orientation - I forget the correct weaving expression - is it trend? Anyway, the more prominent thread should run lengthwise. My pieces from micro tools were not cut very precisely, so I had to do a squaring up exercise of one edge before I could cut replacement squares. I cut full length pieces (from bar to bar or reel to reel) as these help accurate glueing as some of the work will be somewhat out of sight. I let the overlap by the red letter written guide to curtain opening setting be a little larger to retain originality!

Cutting out the old curtain squares shows quite clearly why the curtain no longer worked. The whole area is covered with dozens of long cracks in the rubber layer. Looks like a combination of drying out and conflict in flexibility between the rubber and silk layers. Not only are there cracks and pin holes in the rubber layer, but on the other side of these cracks the silk has corresponding folds. These increase the thickness of the curtain and the clearance at the reels is compromise. This, combined with now permanent "curl" in the curtain due to hardened rubber, makes operation impossible.

Here are some images of the old surfaces and a comparison with new material.

Steven Tribe
8-Jul-2017, 08:02
I forgot mention the back has to be removed to do this. 8 screws, I think.

You must be prepared to check the edge glueing at the overlaps. A loose edge will strike the "edges" and increase friction as well as leading to eventual failure. Quite easy to do, it is much more difficult doing the initial glueing while maintaining the zero position tensioning of the bottom roller. Getting the right "zump" sound when activating the shutter is very exciting. This was done on a uk market 1/4 plate Goerz Ango, but the same principles apply to real LF versions.

Steven Tribe
9-Jul-2017, 02:27
I have re-found another mountable focal plane shutter which covers at least 5x7" where the curtain is non-fumctioning, but the mechanics OK. It is the more complex, two section, type with ribbons and dial adjustable curtain. I have ordered materials from Japan, which seems a good source of rubberised silk curtain material at the right price. I will post when I have further developments!

Steven Tribe
14-Jul-2017, 01:34
The silk/rubber material has arrived from Japan. It has very close and fine weave and is quite a lot thinner than the material from micro tools. The company is Aki-Asahi.com. I need to do a little mechanical work on the next shutter, so, perhaps in a week, I can report back!

I have re-discovered the page at earlyphotography.co.uk which has some helpful explanations and schematics.


Both the shutter I have repaired (Goetz ango - internal cord adjustment) and the one I am doing at present (unknown German - two blind with external tape length adjustment) are shown there.