MS-optics - Perar - fault?

[marcg]

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I've just obtained a Perar 28mm.

It seems to be in new condition - but - there seems to be some problem with focussing.

 

When I first put it on and trying to focus on an image a couple of meters away, the infinity focus - according the rangefinder patch was at the 0.8m mark. -. Moving the lever would then move the image in the patch - into focus at about 3 meters and then at close focus near the infinity mark. - So focussing in revers.

 

Inside the lens there is an inner body of it which swivels - and I kept on moving that into different positions and refitting the lens - getting different focussing results until I eventually got something which seems to be right - in terms of the focussing marks and the patch - although I haven't taken any pictures to see if it is operating correctly.

I can't understand what is happening and I can't see any pattern to it.

 

Does anyone have any idea how it all works?

Even now, as you get towards the infinity stop, there is some resistance - and it seems to need a bit of a push to get it to focus. I don't think that one should be pushing or forcing these precision items.

 

Having done a brief test, I a getting a more focussed image when I estimate the distance than when I use the rangefinder patch.

 

So two questions - what is it that needs adjustment when you get better focus by using the distance scale than the RF patch - and what on earth going on with this lens so that somehow some inner mechanism won't align (presumably) so that the focussing mechanism is completely unrelated to the subject distance.

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[Ecar]

It should not do this. The inside part of the lens shouldn't swivel.

Mine focuses properly. Well, a bit of back-focus at close range (easy to check with the EVF on the M240), but that's to be expected given the lens's formula and simple construction.

Where did you get your lens from, if I may ask?

 

Edit: we are talking about the 28/4 "pancake", not the 35/3.5 "collapsible", right?

[marcg]

It should not do this. The inside part of the lens shouldn't swivel.

Mine focuses properly. Well, a bit of back-focus at close range (easy to check with the EVF on the M240), but that's to be expected given the lens's formula and simple construction.

Where did you get your lens from, if I may ask?

 

Edit: we are talking about the 28/4 "pancake", not the 35/3.5 "collapsible", right?

Yes - the pancake. It got it from an eBay seller in New Jersey - maybe he is a member of this forum..

As I say, it is in beautiful condition but the inner shell - not the small innermost element housing the lens but the part immediately within the outer shell turns within the outer shell.

 

It turns very easily with a gentle push of a finger and with only a slight resistance at one small place. Otherwise it just turns and turns freely.

 

When you turn the lens, it turns the inner shell as well - but if you put your finger on the innershell, then the lens will turn on its own

[marcg]

The arrow shows you what I mean by the inner shell

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[250swb]

I have had the Perar 35mm, and while it is a great lens, it is 'hand made'.

 

I have the inclination from your description and the picture you are posting that one of the locking rings on the rear of the lens isn't tightened enough. So if you aren't able to make a tool to do it yourself I'm sure a camera repair person, or MS Optical, can do it for you. But that is just a theory as to what is wrong.

 

Steve

[marcg]

Sounds like a good answer - although I have no idea which is the locking ring and what tool I need.

 

Also, I suppose that not only would the ring need tightening but also I suppose that it will need calibrating as well.

What a nuisance.

Ms-O are in Japan and I don't want the hassle of sending it out there, then having to argue with customs that it really isn't an import and that I don't have to pay tax!! - know what I mean?

 

I really don't mind trying it myself if I can get or make the proper tool. I don't want to bodge it and damage it.

Also I wonder if Will van Manen in NL can do it.

[marcg]

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In fact the thing is so loose that it rattles!!

[marcg]

Do I gather that if you push your inner shell thing around, it moves the entire lens element - it doesn't move freely on its own?

[250swb]

Without holding it and seeing and hearing where it rattles it seems to me that either

 

one or both of the rings with the two round holes for locking the lens elements in place are loose, or

 

the rings with the two square cut outs that hold the lens unit in place on the mount are loose,

 

or a combination of both.

 

My 35mm would lock up badly without warning, meaning I couldn't extend it from the collapsed position, but knowing what causes the problem, or at least how to deal with it, is the main part of the battle. But they are great lenses so I think its worth keeping on with the fight.

 

Steve

[marcg]

In fact I have checked it against my 35mm and I can see that with the 35mm if you put your finger against the inner shell, it prevents the focussing lever being used at all.

 

Clearly there is something which has become disconnected on the 28 and as you say it needs tightening or fixing.

 

The seller of this lens must have known - and he couldn't have used it like this - except with the distance scale - and it does work very nicely.

 

However for focussing with the patch - it is useless.

I'll call Will on Monday - and maybe it will have to go to Japan.

 

I can't face getting into an argument with the seller and having to face the cost if returning it etc etc etc.

My first bad eBay experience in 6 years.

 

I'll raise it with him, though and see what he says.

[marcg]

It's the inner shell - I don't know what else to call it - which is rattling. It even has a bit if wiggle in it if you rub your finger over it.

I mean that it is the ring which is indicated in the image above. That ring has two tiny cutouts or nicks - opposite each other and it is that ring which is so loose that it rattles and it doesn't grip any of the internal mechanism - so that finger movement of the focussing lever does not transmit fully to the camera RF mechanism.

 

My head hurts!

 

But I agree - they are great lenses.

[Ecar]

Sorry for my previous question, but the 35 has that wobbly (until it's locked into position, which can sometimes be a tricky operation) collapsible central lens part that could have a behavior similar to the one you described.

Seems indeed like something got loose, probably something as irrelevant - until it breaks or gets lost, of course - as a 2c pin...

I'd try and send it back to the seller. He must have known - unless it got somehow damaged in transit. Was is it properly packed? Or perhaps he never really used to lens (or couldn't make it work) and decided to sell it.

This being said, since it appears to be a mechanical issue, I'm sure Will can fix it.

[marcg]

It was beautifully packed - no problem about that.

 

The seller has now said -

Everypart of this lens is in MINT condition, and they are all working properly. The rangefinder mechanism is dead on, and the inner ring is designed to be loose, which means if you are changing the aperture of the lens, there is no click. This lens is based on old lens design, and i rechecked the mechanism of this lens right before i mail you the lens

 

Well he is wrong. IT was not working perfectly at all.

We'll see

[Ecar]

If you bought it on the bay, you should be covered.

I'd send it back and let the seller deal with it. It will cost you return shipping, though.

 

I once bought a Russian lens (a J-3) that arrived with one of the aperture blades missing... The seller insisted that he had *personally and thoroughly* checked it before shipping. He even accused me of having dismantled the lens (yeah, like that's my favourite week-end hobby...). I sent it back, got a refund, and found another working copy from a more scrupulous seller.

 

Good luck. And don't give up - it's a cracking little lens.

[marcg]

OK - the inner ring dropped out. It turns out that it is screwed into the lens body. So far as I can see, the lens is calibrated is by screwing the inner ring to a point where the patch alignment is true.

However if you don't screw it in so that it tightens at the end, then it remains loose and can drop out. On my copy, if you screw it in to the end then the patch won't align at infinity. The bizarre thing is that it actually needs to screw in further than it is able to: infinity is beyond its maximum.

 

There seems to be no way of fixing the inner ring if you want to calibrate it at a point before it tightens ...

... except I notice traces of something like dried glue. Can it really be that you screw the ring into to a point where the lens is calibrated and then you fix it there with glue????

This is my guess as to what has happened.

 

It may be useful to other owners.

 

Looking at the back of the lens with a strong magnifying glass, I see that there is quite a lot of grease on the surfaces. This is a nearly new lens so it seems to me that as it is bedding in, excess grease is working its way out of the moving surfaces.

This is worrying because this is grease which could eventually end up on your sensor.

As the inner lens body moves round within the outer body, you can see grease moving - or being displaced through a minute gap between the mating parts. Are there bearings in there? If so, then what I see is grease being rippled as the tiny bearings travel along the ball race track. If there aren't bearings, then it is for some other reason - but the grease between the mating parts is clear.

I wonder if the lens has been over-greased during assembly? It certainly can't be a good thing having grease coming out - and I was able to collect a tiny drop of it on the end of a wooden toothpick.

 

At the bottom of the female thread in the outer shell there is a rim which mates against a corresponding surface of the inner ring (the bit which has fallen out).

When the inner ring is screwed into the shell, the two surfaces meet - and incredibly (to me) the calibration is only true when the inner ring is fully tightened into the shell so that the two surfaces are fully in contact with each other. If this is right, then there is no calibration adjustment. It is all or nothing - and this means that the parts must be machined to a very high level of accuracy.

 

What is it which ensures that the inner ring won't loosen? - because with constant focussing, there will be repetitive pressure applied against the inner ring which will eventually cause it to loosen - however tightly it has been screwed in.

I think that answer is that it is secured by a small drop of glue - some rigid LocTite.

In the case of my lens, now that the inner ring has come out, you can see the remnants of the glue on the surface of the rim of the outer shell.

 

I have tried to scrape it away with a toothpick - and it is too hard. However, I have noticed that the little remnant of glue is slightly proud of the surface.

This means to me that when one tries to screw the inner ring back into the shell, it is prevented by the glue remnant from seating all the home. We are talking tiny fractions here but it is enough to prevent the RF mechanism from focussing at infinity - and that is exactly what is happening here.

 

I don't know if it is right - but for me it provides a satisfactory explanation.

 

It may be that the lens was never true.

It may be that the LocTite fixing was tainted by over-greasing.

 

Anyway, I think that the lens has two problems. It is over greased - and too much LocTite was applied - or else it was not applied correctly.

 

I'm interested to see that someone else has a lens with an inner ring which comes loose. If you are able to tighten it back so that it focusses correctly then you probably don't have a build up of glue residue. However, the reason it comes loose is because the LocTite bond has failed.

 

I don't know if using LocTite is good engineering.

 

I have had a very positive message from the seller of the lens offering me a partial refund - so that is very decent.

 

Bellamy in Japan and says that he agrees that there is an issue with this lens and has suggested I send it back to Japan.

 

Will van Manen of Kamera Service in the Netherlands also agrees that there is a problem. He says that he can fix it - and says that in 42 years, he has never found a lens which he couldn't repair.

My previous dealings with him have been excellent so I may send it back to him as it is less complicated keeping it within Europe rather than sending it to Japan - with any associated re-import problems.

I haven't decided yet. I am waiting for the seller to confirm the refund so that I will have funds for the repairs.

 

Will tells me that glue is often used to lock pieces into place. However, he says that it should normally be a non-hardening LocTite. The glue in my lens is white, and very brittle. It looks like super-glue rather than LocTite.

 

More pics - http://www.rangefinderforum.com/forums/showpost.php?p=2269950&postcount=14

[Erik Gunst Lund]

Loctite is often used to keep parts from working loose. There are several hundred different types!

 

There are no ball bearings in focusing helicoils.

 

Focusing helicoils are lubricated with grease. Many different types...

 

An amount corresponding to a tiny drop collected with a toothpick is normal and will not ham your camera.

 

Yes the parts must be clean at the contact surfaces when assembled, to be able to reach infinity.

 

Any decent repair tech can do this repair.

 

Sounds like someone applied a lot of torque in the wrong place to make that Loctite fail...

 

This would not happen for normal use...

[marcg]

Well there is no damage or evidence of that kind of force being applied. Also - it looks to me like superglue - and not Loctite - it is clear/translucent and very dry and very brittle.

 

I've sent it to Will van Manen in Netherlands who has see all of the photos and is confident that he can repair it.

 

Should I have it coded at the same time?

[Ecar]

Not sure about coding: if you are planning to use it with the M240, the code reader can can be tricky and not play well with the colour/material of the mount.

Mine is uncoded and I select the code manually.

I'd just ask Will and see what he thinks.

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[marcg]

Thanks - I'll do that.

It gets used with an MM

[Erik Gunst Lund]

I would definitely code it, no problem for any M reading a coded lens that is done properly.