Light leak on a Mir Lens Mount.

[SCOTFORTHLAD]

I am expecting to receive a Mir shortly,which has been troubled by a light leak.Advice from a reputable source is that one of the culprit areas for this is the lens mount,and that this can be rectified by sealing behind the mount with some cord/string,presumably waxed or similarly treated.

Has anyone any previous experience in this particular treatment on a Mir,or any other of the similar Zorki models.

Any comments or advice would be greatly appreciated.Thanks.🙂

Brian.

 

[SCOTFORTHLAD]

I am expecting to receive a Mir shortly,which has been troubled by a light leak.Advice from a reputable source is that one of the culprit areas for this is the lens mount,and that this can be rectified by sealing behind the mount with some cord/string,presumably waxed or similarly treated.

Has anyone any previous experience in this particular treatment on a Mir,or any other of the similar Zorki models.

Any comments or advice would be greatly appreciated.Thanks.🙂

Brian.

Update--the Mir arrived today,and very nice it is too!Looking at the lens mount,unless there is a cavity behind it,it is such a nice snug fit,that some sort of sealing gasket would need to be very lightweight indeed.Assuming that it is at all feasible?

 

[Xmas]

Brain

If the materials can stand the liquid and setting any of the thick setting sealants would do, provided they dont dry translucent. Bath tub calk (RTV) releases acetic acid (stop bath), but some other sealants are more innocous. Apply a releasing agent to at least one surface to allow future maintenance.

Noel

Noel

 

[wolves3012]

We are talking about the Zorki 4 variation aren't we? Take a peek at the Zorki 4 CLA "how to". I've noted the light seal around the mount and you can see on photo 42 where it goes - around the lower part of the mount where it fits against the outer body. This could be the culprit if the body has ever been removed, it's a black string of some sort - maybe wool (or yak hair!).

 

[wolves3012]

Brain

If the materials can stand the liquid and setting any of the thick setting sealants would do, provided they dont dry translucent. Bath tub calk (RTV) releases acetic acid (stop bath), but some other sealants are more innocous. Apply a releasing agent to at least one surface to allow future maintenance.

Noel

Noel

Bathtub sealant does release acetic acid (aka vinegar) and acetic acid will corrode the alloy parts - not recommended.

 

[SCOTFORTHLAD]

We are talking about the Zorki 4 variation aren't we? Take a peek at the Zorki 4 CLA "how to". I've noted the light seal around the mount and you can see on photo 42 where it goes - around the lower part of the mount where it fits against the outer body. This could be the culprit if the body has ever been removed, it's a black string of some sort - maybe wool (or yak hair!).

Hi,
As you say ,this is a Zorki 4 variation,and the guidance to the relevant section in your excellent thread is very helpful.I did look through it quickly,yesterday,but didn't read the text closely enough so missed the reference to the string sealer.

The pointer to the sealing string as a possible cause came to the previous owner from Oleg,and your excellent details at least explain more fully what he was referring to.(I say the previous owner,but I myself owned the camera even earlier,and would love to get it 'operating' again.)

If I get at this string gasket and it is damaged,it sounds as if it could be replaced by something similar--I hope?
With reference to the shims under the lens mount,are they metallic,or somthing more fragile?I have seen mention of paper shims in FSU lenses,I assume that these would be well past their sell-by date by now.

Thanks for the help,🙂
Brian.

 

[SCOTFORTHLAD]

Brain

If the materials can stand the liquid and setting any of the thick setting sealants would do, provided they dont dry translucent. Bath tub calk (RTV) releases acetic acid (stop bath), but some other sealants are more innocous. Apply a releasing agent to at least one surface to allow future maintenance.

Noel

Noel

Thanks for the suggestions Noel,it may be that some black wool, from the wife's sewing basket, and glue, could be the answer

Brian.

 

[wolves3012]

Hi,
As you say ,this is a Zorki 4 variation,and the guidance to the relevant section in your excellent thread is very helpful.I did look through it quickly,yesterday,but didn't read the text closely enough so missed the reference to the string sealer.

The pointer to the sealing string as a possible cause came to the previous owner from Oleg,and your excellent details at least explain more fully what he was referring to.(I say the previous owner,but I myself owned the camera even earlier,and would love to get it 'operating' again.)

If I get at this string gasket and it is damaged,it sounds as if it could be replaced by something similar--I hope?
With reference to the shims under the lens mount,are they metallic,or somthing more fragile?I have seen mention of paper shims in FSU lenses,I assume that these would be well past their sell-by date by now.

Thanks for the help,🙂
Brian.

Can you say any more about the nature of the leak? Besides the sealing-string I mentioned, there's a small seal behind the self-timer arm. The other possible cause is a badly-fitting back. Other than that, missing screws in some areas could cause leaks. Black wool twisted tight and glued with 2 or 3 dabs of PVA would probably be good for the mount seal.

The lens shims aren't metallic (not on any I've seen anyway). They're a kind of compressed paper with a slightly shiny look, hard to describe. If you're careful with them there shouldn't be a problem. If you do any replacing, use something that won't compress easily. Also, don't do the mount screws overly tight, there's no need. Jay's excellent site mentions some materials he's made shims from - hats off to him for the patience to make them!

 

[SCOTFORTHLAD]

I'm not too sure of the exact nature of the light leak,Kully who had the Mir before me,opened up a thread here for advice, at the time,but that was several months ago.I am sure that he followed up all the options,and the lens mount suggestion is probably the last option.Hopefully it will be solveable.

Thanks again for the tips.

Brian.

 

[SCOTFORTHLAD]

I've stripped the Mir case down as shown on Wolves thread(photos 33--42),the light seal around the lens mount is completely detached,and looks to be shorter than it should be .Someone must have opened the camera before,as the light seal is made of modern light seal foam.
I'll make up a new seal and put it all back together---hopefully the problem will then have been solved.😉

Brian.

 

[SCOTFORTHLAD]

I've stripped the Mir case down as shown on Wolves thread(photos 33--42),the light seal around the lens mount is completely detached,and looks to be shorter than it should be .Someone must have opened the camera before,as the light seal is made of modern light seal foam.
I'll make up a new seal and put it all back together---hopefully the problem will then have been solved.😉

Brian.

All back together now---Fingers crossed for a problem solved,🙂

I'll let you know in due course how it goes.

Brian.

 

[SCOTFORTHLAD]

Just took my second light leak test film in for processing.

The first one was a disaster,not from any light leak,just that it was completely blank.I had misloaded the film,and it had not been winding on.😱

I was a little suspicious when I rewound,even after a service and new curtains by Oleg it was a tad too smooth!

Still I live in hope for the latest attempt.

I'll keep you informed.

Brian.

 

[Ash]

Good luck Brian!!!

 

[Xmas]

Ash

The Leitz hoods are real expensive suggest, a step ring, chepo filter, and a chepo hood.

Noel

 

[SCOTFORTHLAD]

Unfortunately my efforts have still not succeeded.I attach a couple of scans which show the light leak as it has ocurred on almost all of the 24 exposures from my test film.
To date the lens mount and the internal casing around the shutter has been sealed,plus the external screws.I have not sealed the rebate in the camera's body into which the removable back panel sits,nor have I sealed the delayed timer switch.

Or could this be a shutter malfunction.

Any comments welcome.
Thanks,
Brian.

 

[kully]

It's cursed Brian, nothing short of an exorcism is going to cure it 🙂

The self-timer - I took out the lever and blu-tac'd and taped it all over - still saw the light leak.

 

[SCOTFORTHLAD]

You may be right Kully,it seems worse now than when it first appeared.It's a pain,because the camera is in such good condition in every other way.

Nil Desperandum😉

 

[Xmas]

Brian

Because of the colour it is from the front of the film, so it is probably from the lens area or the take up spool area.

Does it extend into the sprocket rebate area, if not it is the shutter. If the shutter does not overlap enough you should get a finishing side problem as the blinds overlap more and more and the shutter is set.

Perhaps there is a foreign body in the blind frame slots, borrow small mirror, lock open shutter and try to see e.g if a bit of film has lodged...

Noel
P. S. it looks as if one of the tapes is the wrong length.
P.P.S. if you fit a cap as you wind/cock the shutter this would allow the problem to be confirmed...

 

[SCOTFORTHLAD]

Noel,
The fogging goes right across the film including the rebates.

As the fogging is more pronounced now than it was originally,it may be that when fitting a fresh seal underneath the lens mount, the mount may not be fitted back on as tightly as it should.

I generally had a lens cap on the lens,but probably took it off before winding on.

Brian.

 

[kully]

Hallo Noel,

I shot a roll making sure I put the cap on before winding on - the problem was stil there.

Very frustrating Brian, especially as it's not there at all on some frames...