FSU Lens on FSU Camera!

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mike goldberg

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Hi All,
I ran into some unanticipated trouble and miserable looking negs recently,
when testing a Fed-2 with a J8 that had been collimated for the Bessa R
by Brian Sweeney.

Then, I wanted to know if I could use my CV 75/2.5 on the Fed-2.
Here's what Brian, our resident "lens expert" had to say,

It might be a real problem. The RF coupling of the FSU cameras often miss lenses made outside of the USSR, the wedge shapped pickup slips under the
RF coupling of a number of lenses. ALSO: the RF may be set differently, and it
may miss the focus. It's the same problem of using an FSU lens on a Leica,
but in reverse.

With so many FSU camera bodies out there, and a world of m39 screwmount
lenses available, I thought it would be worthwhile opening the discussion to others.

Ciao, mike
 
I wouldn't expect a J8 to deliver bad results in this situation unless you're shooting very close and wide open. At f/2.8, the DOF ought to cover the difference in focal registration.

I use FSU glass on my Bessa R all the time, but I'd never really thought about using my Voigtlander lenses on a Fed. I tried mounting my CV 28mm f/3.5 on my Fed 3 a while back, and did have some trouble with the focusing wedge.

I'd certainly take Brian's word for it. He's very knowledgeable, and has earned his respect and reputation on this forum.
 
Hallo Mike. You've come up against the optical incompatibility issues first identified ( to my knowledge) by Dante Stella here - http://www.dantestella.com/technical/compat.html. In essence the Soviets seem to have adopted a Zeiss standard for their LTM lenses, so lenses adapted to ordinary Leica standards are not entirely compatible. In my experience a new-from-the-box I-61 ( for example) focussed on an object 1m away according to a accurate Leica rangefinder, will actually be focussed at around 1.10. This may not seem a disaster, but when standards are mixed, shooting wide open close up, or with longer lenses, it can become a problem. I didn't want to believe Dante Stella, but experience has taught me I was wrong :(

The other issue you raise is less disturbing: the Soviets seem to have chosen the adjustable probe rangefinder because it allowed for easier, less exact, manufacturing processes. Problems are usually only encountered with lenses that do not have a full rangefinder cam (as the FSU optics do) but instead link the lens to the RF using a narrow tongue. Some lenses with a very thin full cam might also pose a problem, but I would not have thought that the C/V lenses would have trouble mounting. On several occasions Jay has listed incompatible lenses and most seem to be older Canon LTM or a few Leitz models.

All the best, Ian
 
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when standards are mixed...
Thanks all, above,

I take the key words, when "standards are mixed," from Jocko above,
and from Brian's message to me in flickr, previously quoted.
What was most disturbing in the negs+CD from the test, were the
erratic results. Some frames looked like I didn't know how to focus the Fed-2 :rolleyes:
This one below, close in, but not with the lens fully extended,
was OK. Perhaps it was OK, because it was at f8.

http://www.flickr.com/photos/mikegoldberg/464128394/

Anyhow, given the comments thus far, and good 'ole dantestella...
it pays to check things out.

Cheers, mike
 
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I don't think mixing standards has anything to do with it. It is more likely to be merely be a matter of accumulated accident/abuse of the follower arm over the years, which can hardly be surprising. My FED-1 was suss with its own lens. It worked OK but didn't feel right. The Leitz and the rigid I-50 felt fine. It was clear that the arm was bent and barely contacted the FED lens. It was fixed by bending it back. There are some notes here

http://www.rangefinderforum.com/forums/showthread.php?t=9779

I don't think it would be a good idea to bend the arm in situ.
 
You'd be amazed to note that even J-12, a very Soviet LTM lens, will often be difficult to mount in some FED and Zorki. FED-2, Zorki-3/4 are among the cameras which would not allow easy fitting. Often because the RF arm hangs too low. The arm can be bent upwards a bit, and when done, the J-12 will easily mount.

Soviet FED and Zorki allow far more RF adjustments than a Leica or Canon can.
The difficulty lies in how much to adjust the several parts involved. But once calibrated, any non-Soviet LTM lens with a full barrel cam will mount and focus correctly.

On the other hand, I've not had any problems using Soviet Jupiters and Industars in my Leica cameras either. My J-3 worked right as I got them. Judging from their worn and tired looking barrels, it seems that they lived useful lives- hence the wear. This would either say that they were right on from day 1 or else had been calibrated for real-world use. :)

The only problematic lenses I have are some J-9 85mm. Not because of compatibility problems. These wouldn't even focus with FED or Zorki. The problematic lenses won't work because someone had previously tinkered with them, and botched the work. However the good J-9s would focus right, regardless of the camera they are put on.

Jay
 
Nickfed said:
I don't think mixing standards has anything to do with it. It is more likely to be merely be a matter of accumulated accident/abuse of the follower arm over the years, which can hardly be surprising. My FED-1 was suss with its own lens. It worked OK but didn't feel right. The Leitz and the rigid I-50 felt fine. It was clear that the arm was bent and barely contacted the FED lens. It was fixed by bending it back. There are some notes here

http://www.rangefinderforum.com/forums/showthread.php?t=9779

I don't think it would be a good idea to bend the arm in situ.
Click to expand...


Each time the arm is adjusted, the pivoted tip (tiny tear drop in the earlier cameras, replaced by the more common larger sloped tip) has to be adjusted as well. The angle of this sensor tip is critical to the rangefinder's close focus accuracy. This sort of adjustment is there by design.

Jay
 
ZorkiKat said:
Each time the arm is adjusted, the pivoted tip (tiny tear drop in the earlier cameras, replaced by the more common larger sloped tip) has to be adjusted as well. The angle of this sensor tip is critical to the rangefinder's close focus accuracy. This sort of adjustment is there by design.

Jay
Click to expand...

Not true.

By bending the arm you are merely moving the tip up and down. It has to move back and forth to have any effect on the rangefinder. That's its job when the lens moves in and out. Even a fair amount of movement side-to-side would be permissible. You don't have to know too much trigonometry to realise that the generous ratio of arm length to end movement makes things quite undemanding mechanically, which is just as well, and of course it minimises any complications of linear variation of rotary movement. It's all there in the sine tables.

In my case the tip was lifted 1mm or so. If it works at all, I guess it would never need to be bent much more, but to change the effective length of the arm would require some truly serious effort.
 
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I'm glad this Thread got a buzz going...

For me it's clear: I'm using a NON-collimated J8 from the 1950's, and
the Fed-50/3.5 Elmar type and an I-61 are waiting for me at the PO.
The hours at the PO are erratic these days with the workers cutting
back on hours, pressing for higher wages, benefits etc.

The Fed-2 focusing patch is quite good, and yes, the V/F is a bit dim.
The bright CV 75/50 VF [shoe mounted supplementary viewer]
sits atop the Fed-2, because I'm not using it on my Bessas at this time.

In short, the Fed-2, especially with the collapsable Elmar type will be
a sort of, dedicated 50mm RF. I've also heard that the I-61 is
quite sharp.

Anyhow, cheers...
mike
PS: There seems to be another message herein: Take care of that
little tongue where lens thread meets screwmount. THAT is what
engages the RF focusing mechanism.
 
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Nickfed said:
but to change the effective length of the arm would require some truly serious effort.
Click to expand...
Nick

It is not totally clear unless you brouse Jay's site that there are two bends

the arm to clear lens bodies for mounting &
the little follower to allow the effective radius of the arm to alter, twist on pivot

Sorry, and as well the leicas do have a similar adjustment but it is less obvious and I've forgotten...

noel
 
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Nickfed said:
Not true.
...but to change the effective length of the arm would require some truly serious effort.
.
Click to expand...

You're wrong, Nickfed.

It's not just the effective length of the arm which changes when the sensor tip angle is adjusted. And if you look at the way the lens cam engages with the sensor tip, you'll see that the cam won't be touching the same part of the sensor as it moves in focusing. Note too, that the sensor tip is shaped in a peculiar manner- not round, but tear drop or comma in form. The early FED used a rectangular oval. But it appears that the shape evolved into something else due to functional necessities. If it were just a question of arm length, the sensor tip would have just been plain round or some regular shape.

Maizenberg's repair instructions define the importance of the sensor tip's angle of slope in the ability of the RF to focus correctly at minimum distances. He knew why the sensor tip used in FED and Zorki was adjustable- he was around in the factories and workshops - and privy to the people who were designing this.

A deviation by as little as a fraction of a degree on the slope itself is sufficient to affect the RF's focusing accuracy at close distances. When the RF sensor arm is bent up or down, the sensor tip's angle changes. Thus it becomes necessary to adjust its position again when the arm is modified. Observations from the repair and adjustment of many FED and Zorki cameras also confirm this.

The angle of the sensor tip varies from camera to camera. It's almost never found in the same position. Each rangefinder in a FED or Zorki appears to have been assembled with less uniformity. Each therefore would need individual adjustment so that each can focus properly throughout its focusing range. There is no other reason why the sensor tip is pivoted- it's not a whim, but rather a design required by necessity. The necessity for individual fine-tuning.

Many people complain of cameras which do not focus properly, particularly in the minimum end of the range. Most of the time, it's because the sensor tip isn't properly angled.

The pivoted sensor tip also allows the RF of a camera to be adjusted for whatever lens is to be used with it. A FED from before WWII will have an RF calibrated for a lens whose RF camming is very different from a Leica. Such a camera can be recalibrated (with perhaps a change of lens mount) to be used with Leica lenses or post war Soviet LTM lenses when the RF is adjusted both for infinity (with the known screw between the ports) and minimum focus using the pivoted sensor tip. Perhaps the Soviet engineers considered this and made it one of the reasons for using an adjustable sensor tip instead of a roller wheel as found in Leica or Canon.

Jay
 
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mike goldberg said:
mike
PS: There seems to be another message herein: Take care of that
little tongue where lens thread meets screwmount. THAT is what
engages the RF focusing mechanism.
Click to expand...


That's why instructions say that the lens must be set to minimum focus first before fitting on the camera. The cam retracts into the barrel, clearing the way for the sensor tip as the lens goes on the camera. When the lens RF cam is extended as the lens is being mounted, there is risk of changing the angle of the RF sensor tip, and when this changes, the camera RF's accuracy is compromised.

Jay
 
Xmas said:
Nick

there are two bends

the arm to clear lens bodies for mounting
Click to expand...

I am referring to the arm on the pivot that swings the rangefinder. The one shown in the picture. I'm sure I described physically bending it, not rotating it on any pivot. I even mentioned it's on a square drive, which more or less kyboshes any thoughts in that direction. The bend is done to ensure the "sensor' bears properly on the lens. Furthermore, by doing so, I think you can bet your balls that all you are doing is putting the sensor back where to it was in the first place. There is nothing to suggest this is down to manufacturing variation etc. it's just a little soft metal bar that is slightly exposed to abuse and gets a bit over fifty years. It has no effect on rangefinder geometry, well, measurable effect anyway. Calling this "critical" is just theoretical fantasy. Mind you, there is a lot of that around.


Rotating the "sensor", which, while probably less critical than people think, does nothing to solve the problem, indeed may make it worse. Maybe I should have pointed that out before! But nobody would try fixing it by doing that, surely?
 
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I have FSU lenses, CV lenses, and just one LTM lens which does not fit either of these categories - a Nikkor-Q 13.5cm f3.5. That is the one which causes problems with FSU bodies because it does not have a full-circle RF cam, just a tongue about 15mm long at the top and cut on a straight 45 degree angle at the ends. When I first bought it I jammed it on a FED-2 and the only way I could remove it was to open the shutter on B with a locking cable release and gently pull back the cam lever from behind. Thankfully there was no film in the camera at the time, and even more thankfully, it was not a bottom loading body.

Cheers, Peter.
 
I had the problem with the J-12 on a FED-2 where the rangefinder arm was too low and jammed against the lens body, which I fixed by bending it up a millimetre or so. And it didn't affect the focusing at all (I checked - the indicated distances for various focus targets using a 50mm lens where exactly the same before and after I adjusted the arm).
 
oscroft said:
I had the problem with the J-12 on a FED-2 where the rangefinder arm was too low and jammed against the lens body, which I fixed by bending it up a millimetre or so. And it didn't affect the focusing at all (I checked - the indicated distances for various focus targets using a 50mm lens where exactly the same before and after I adjusted the arm).
Click to expand...


Sometimes, luck can smile and allow this sort of adjustments without altering the RF sensor tip's accuracy. I've done this bending thing with 6 cameras for J-12 accomodation so far: 2 FED-2, 1 Zorki-4, and 3 FED-1. Only 2, one of the FED-2 and the Zorki-4 did not require recalibration. The others, particularly the FED-1, with their tiny tear-drop tips, required minimum distance adjustment after bending the rf arm.

Jay
 
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