Problem with my 'new' Compound shutter: my own fault!

[Paul Kinzer]

I just received a 300mm Schneider convertible Symmar* in the older Compound shutter that I know they came in. The seller had said the shutter would fire inconsistently, but I recalled reading that you need to wait a bit after cocking these pneumatic shutters before firing them. Sure enough, if I waited several seconds before tripping after cocking, it fired at increasingly longer speeds as I went down the scale. Yay!

But not so much now. The speeds seemed a bit fast, and I also remembered reading that putting a bit of dry lubricant into the piston could make the shutter able to fire more quickly, and that it can help with speed accuracy, too. but, as I should know by now, not everything one reads is true. Now, the shutter fires way too quickly. as in, 1 second seems to fire at 1/50th. I assume I broke some kind of seal, and that the piston is no longer doing its job.

I have not yet searched the internet for a solution (I'm afraid). and hope for help here.

But, hey, I'm not very patient, so I'll go looking as soon as I post this. If I find and easy, non-shutter-wrecking solution, I'll come back and post it.

*This was one of those eBay deals I look forward to. In addition to a shutter that worked (notice the past tense!), contrary to how it was advertized, the ad also said there was haze in the front element. This was one of those lucky times when I unscrewed it, and the 'haze' just wiped right off, revealing almost perfect glass! This is my third Schneider lens where this has been true. This one makes up for the 135mm Fuji W lens that was sold with the same warning. That haze was internal, and would not wipe off. But it's so minor you really have to look through it at the right angle under the right light to even detect it) that I'm going to live with it till I see what effect it might have, if any.

Paul

[AJ Edmondson]

It sounds as if the piston is sticking as opposed to moving over the range determined by the setting. You might try removing the end caps located at the ends of the cylinder and check for cleanliness (lack of any type residue). These are really good shutters (within their limitations) and Carol Flutot or SK Grimes are excellent at repairing them.

[Paul Kinzer]

^^

Actually, that's exactly what I did, and it was then that the problem started. I'll post a photo of the piston end caps in a bit. They have some copper-colored circles inside them, and I'm wondering if these are seals that came off when I removed the caps. And now I wonder if, when I screw them back on, the seals no longer seal.

Should I put something in there to re-seal them, and if so, what?

[Paul Kinzer]

I found this page here on the forum. Someone was having a problem very similar to mine, and the last commenter wrote:

'The end caps have little gaskets that may have dried out. If the caps don't hold an air tight seal the shutter can act like that. Try removing the caps, add a drop of oil to each, let it sit for a minute to swell the gasket and reinstall them. It might solve your problem.'

I tried it: nope! And I waited a lot longer than a minute. I still think non-working seals might be my problem, since it worked okay until I removed the end caps.

I also tried 'exercising' the piston by gently pushing it back and forth with the end of a paper clip. I was careful not to force it in any way. I put a bit of dry graphite lubricant into the bit of the piston shaft where it did not go completely freely when cocking the shutter. I don't know if it is even supposed to go there, but found that, when I pushed it there with the caps removed, with the shutter set at 1 second, and then tripped the shutter, the shutter did something different: instead of just firing at a high speed, it opened and got stuck. A touch to the cocking lever made it close.

This is what made me wonder if you had it right, AJ Edmondson, and it needed some help. It looked clean, and moved fairly freely, but this is when I figured it could not hurt to put a bit of graphite into the piston cylinder. That fixed the getting stuck problem. It doesn't do that anymore, but it doesn't work, either. It still fires at a single, high speed, no matter the setting.

[Paul Kinzer]

Okay, it's me again, making comments on my own query. I just tried something else: With the end caps off, I cocked the shutter, which moved the retarder in the piston cylinder into position. I then put a fingertip tightly against each end of the cylinder, forming my own seal. Then I tripped the shutter. It opened, and stayed open until I released one of my fingers. Then I figured out that, if I did not squeeze too hard, so that the flesh of my fingers intruded into the shaft of the cylinder, the shutter opens and then closes! The volume of the air in the cylinder obviously has to be just so in order for all to work as it should.

So it seems that the seals are the issue. The problem now is, how to fix them.

[Jac@stafford.net]

I put a bit of dry graphite lubricant into the bit of the piston

Please never use dry graphite in any part of a lens. It has the tendency to migrate and really muck-up the optics,
.

[Paul Kinzer]

Please never use dry graphite in any part of a lens. It has the tendency to migrate and really muck-up the optics,
.

I'd be interested to hear more about this, as I've done it with shutters that I could not get to work in any other way, and my own experience has been that, if only a tiny bit is used, and the excess blown out with a can of air after a bit of exercise, the only issue is some specks of graphite dust on the inside of the glass. It's easily wiped off, and graphite is very soft (that's why pencils work), so it doesn't harm the glass, which is very hard. And I've found that these specks only appear for a while after doing this. I have lenses that I did it with years ago, and have not seen any specks for a very long time. And the shutters still work.

While I understand that it may not be the done thing by professionals, I'm on a very limited budget. If I can buy a shutter that doesn't work for a very low price, and get it to work for almost nothing, that's the choice I'm going to make, because I cannot afford a different one.

I apologize if this seems snarky, or even negative. It's not meant to! I'm just making my case.

By the way, here's a photo of the end caps:



Does anyone know if those copper-colored bits are the seals, and what might be done with them?

[Chris7521]

I'd be interested to hear more about this, as I've done it with shutters that I could not get to work in any other way, and my own experience has been that, if only a tiny bit is used, and the excess blown out with a can of air after a bit of exercise, the only issue is some specks of graphite dust on the inside of the glass. It's easily wiped off, and graphite is very soft (that's why pencils work), so it doesn't harm the glass, which is very hard. And I've found that these specks only appear for a while after doing this. I have lenses that I did it with years ago, and have not seen any specks for a very long time. And the shutters still work.

While I understand that it may not be the done thing by professionals, I'm on a very limited budget. If I can buy a shutter that doesn't work for a very low price, and get it to work for almost nothing, that's the choice I'm going to make, because I cannot afford a different one.

I apologize if this seems snarky, or even negative. It's not meant to! I'm just making my case.

By the way, here's a photo of the end caps:



Does anyone know if those copper-colored bits are the seals, and what might be done with them?

They are seals. If they are bad or the caps are not tight, the piston will not slow the speeds down because the air leaks out. I have made seals for a shutter using a very thin gasket making paper found at automotive stores if you need replacements.

[domaz]

Slightly related question- does anyone know of an off the shelf replacement for Compound shutter end-caps, or at least the threading they use? I took one to the hardware store and couldn't find a match with modern common threads, using their thread finder board.

[John Kasaian]

I've always heard that nose oil was the ticket for lubricating Compound shutter pistons?