View Full Version : Swapping shutters/lenses

7-May-2017, 13:23
I have two shutters; both Synchro-Compur-P.

One of them has a decent - but currently redundant - Xenar 135mm f4.7; the other has an Angulon 90mm f6.8. The bad news is that the second shutter has timings all over the place while the first is fine. Since I have an alternate 135 in a Seiko shutter, I'd like to swap the Angulon into the shutter currently holding the Xenar; then at my convenience I can investigate sorting out the timing issues on the second shutter.

My understanding is that the lenses front and rear are simply screwed into the appropriate side of the shutter - is this the case? Or is there a hidden locking screw perhaps, or are thread lock compounds used? Or do my lenses simply not want to come to bits after sixty or seventy years?

I have located the Compur repair manual, but an initial scan doesn't suggest anything.

Any advice gratefully received...


7-May-2017, 14:56

You are correct - the lenses are simply screwed into the appropriate side of the shutter. You also need to transfer any shims that may be present, as well as the aperture scale. If the cells don't come out, you may need to use a rubber strap wrench or ribbed gloves to get a better grip.


7-May-2017, 22:35
Thanks Kumar; I'd assumed that but wasn't certain and didn't want to force anything. I'd worked out the aperture scale had to swap over but had wondered also how the precise positioning was maintained - shims are an obvious idea (doh!).


7-May-2017, 23:47
One of the first things to do before any work is to get a pair of measuring precision calipers to measure the distance between (at least) the outside front + rear barrels while still in the old shutter, so you can compare this measurement when the cells are screwed into the new shutter...

Having a decent set of calipers is almost a must have for anyone who tinkers with gear... There are some inexpensive models that are OK if you carefully hand select a good set (try before you buy)... When closed, and you hold the matching measuring surfaces to the light, they should close to an almost invisible and even line... When you open and close them after they are zero'ed, they should zero again exactly, and should repeat a measurement of something exactly every time, and find the point where it is snug enough to read and repeat (not get "sprung" or creep...) If you actually make stuff requiring precision, get a better pair, but an OK cheaper pair is usually OK for simpler casual measurements, like size of a lensboard, cut-outs, general size of a lens barrel, etc... Digital, dial, you choose, but I like dial when I'm sanding or filing something, as the needle gets nearer to the perfect thickness... (Helps me visualize the rate of material removal)...

Good luck!!!

Steve K

8-May-2017, 13:11
Thanks Steve; I have olde-worlde mechanical precision measures at home, and more modern stuff available at work.

Good call on the base measurements.


8-May-2017, 13:45
Hmm. Three out of four elements removable, but the front of the 135 is being stubborn...


Mark Sawyer
8-May-2017, 14:07
Keep in mind that the f/stop scale will be off...

9-May-2017, 10:43
Yep, need to swap the scales. The front element has succumbed to brute force and ignorance - you can tell I'm an engineer :)

Thanks, all.


21-May-2017, 05:16
Hi, what I do when confronted with a stuck lenselement, is take a piece op pipe that fits around the element and heat it with a hairdryer. I then take the warm pipe (80 C) and slide it over the stuck element so that it is in contact whit the part of the shutter where te element is threaded in. Wait for a minute, check ik the threaded part is nice and warm, and then unscrew the element. The warmth softens the grimy grit stuck in the thread and it also expances the threaded parts of the shutter and the stuck element. Because the threaded part of the shutter has a slightly larger diameter, it'll expand more, come loose fron the element and voila, problem solved!

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