FED 6.3/100 lens LTM problem

[john341]

What is it with the 100mm FED 6.3 l3ns? I cannot get rangefinder alignment with this lens. I seems that the lens mount is too thick as the distance scale does not finish on the top of the camera but to the side. I have tried this lens on many ltm bodies and cannot get a match. Does anyone have any experience with this lens??

 

[photovdz]

It's normal..; it suppose to be somewhere like 10:30 or 11 o'clock...
make a test roll... as those lenses are not standard calibrated... you have to match them to certain fed body (and vice-versa)...

 

[varjag]

Yes, the lenses and pre-war FED bodies were supposed to be matched for each other in a workshop.

 

[jc031699]

Quick note from my cleaning of my newest lens: FED 100mm f6.3
I could not find any other online resource at all for how to do this. It was pretty straightforward in the end.
It opens by taking out the 2nd ring in from the back. This allows the optical unit to slide out the front.

There are three grub screws that hold the focus ring in place. Taking those out allows the ring to slide off the front.

Unscrew the front and rear lens units and clean them. Each of these is a cemented doublet. The FED lens is a four element in two groups lens. Not sure if this means it's a topogon type design... (the canon 28/2.8 and orion-15 seem to have a similar arrangement) These lenses cleaned up nicely.

The aperture ring can be taken off, by unscrewing the two threaded aperture control pins, but this can/will release the aperture blades which will fall out if you are not careful. You have to use a cork or some other cylinder to press the aperture blade assembly into place in order to replace the aperture ring and place back the threaded pins. The surfaces between the aperture ring and the optical unit may need cleaning/light regreasing.

The helicoid will unscrew completely if you take out the small silver screw in the side of the focus unit. Be sure to mark the helicoid so that it can be replaced into the right starting point. I used some NGLI 2 grease, probably could have used even heavier to remove some play in the helicoid.

Interestingly, the rangefinder cam is spring loaded, and can be pressed out the back gently for cleaning/greasing of the sliding contact surface.

There were tons of shiny surfaces that I blackened with India ink to decrease internal reflections:
1) outer shiny silver inner diameter of aperture ring
2) surface of front lens unit
3) inner surface of optical unit front
4) inner surface of optical unit back
5) all inner surfaces behind the rear lens unit - 2nd ring from the back, 1st ring from the back, inside of focus unit, inside of rangefinder cam
7) aperture blades front and back with sharpie (like Brian's I-61 mod) - they were shiny blue to start

The first ring from the back comes out easily, but I'm not sure what it does as part of the rangefinder cam assembly.

I hope all of this, plus my Leica FIKUS clamp on hood will help to reduce the flare that I've seen on posted images.
It is super tiny, very cute, and solid brass.

 

[Valkir1987]

It's an old 'Tele Tessar' design lens. It needs to be collimated and adjusted by a workshop to work on a Leica or any other L39 body. If I remember correctly, the ring that touches the rangefinder cam can be adjusted at the right height.

Please do not remove the 'shiny blue' of the aperture blades with a marker. A limited amount of lenses with a blue aperture was made for the Fed 1C series. Theses lenses are rare and rather valuable. Most 'regular' pre war Fed 100mm lenses come with black aperture blades. This is more a collectors lens than a performer.

You can find the optical design here.

Pre-WWII Lens FED-36 6,3/100 & viewfinder FED 100 mm - USSRs Phototechnics

The FED-100 100 mm f/ 6.3 Lens. Specs. MTF Charts. User Reviews.

 

[jc031699]

It's an old 'Tele Tessar' design lens. It needs to be collimated and adjusted by a workshop to work on a Leica or any other L39 body. If I remember correctly, the ring that touches the rangefinder cam can be adjusted at the right height.

Please do not remove the 'shiny blue' of the aperture blades with a marker. A limited amount of lenses with a blue aperture was made for the Fed 1C series. Theses lenses are rare and rather valuable. Most 'regular' pre war Fed 100mm lenses come with black aperture blades. This is more a collectors lens than a performer.

You can find the optical design here.

Pre-WWII Lens FED-36 6,3/100 & viewfinder FED 100 mm - USSRs Phototechnics

The FED-100 100 mm f/ 6.3 Lens. Specs. MTF Charts. User Reviews.

Thanks! Yes, I am planning to shim the optical unit to see if I can get the RF calibrated without touching the cam.

Fortunately all of my blackening steps are totally reversible. The sharpie comes off with an alcohol wipe, and so does the India ink. All of these are pigment and not paint or chemical removal of the bluing.

I intend to use this, it has zero value to me as a collectible.

 

[jc031699]

It's an old 'Tele Tessar' design lens. It needs to be collimated and adjusted by a workshop to work on a Leica or any other L39 body. If I remember correctly, the ring that touches the rangefinder cam can be adjusted at the right height.

Please do not remove the 'shiny blue' of the aperture blades with a marker. A limited amount of lenses with a blue aperture was made for the Fed 1C series. Theses lenses are rare and rather valuable. Most 'regular' pre war Fed 100mm lenses come with black aperture blades. This is more a collectors lens than a performer.

You can find the optical design here.

Pre-WWII Lens FED-36 6,3/100 & viewfinder FED 100 mm - USSRs Phototechnics

The FED-100 100 mm f/ 6.3 Lens. Specs. MTF Charts. User Reviews.

Any hints on how to adjust the height of the cam? It does not come close to reaching infinity on the rangefinder and needs to protrude a couple of mm beyond where it currently sits.

 

[Valkir1987]

Any hints on how to adjust the height of the cam? It does not come close to reaching infinity on the rangefinder and needs to protrude a couple of mm beyond where it currently sits.

The helical must be assembled properly of course, but a fine adjustment is possible. On the ring of the rangefinder cam, you see a little hole. This hole was intended for a hook wrench. Of you loosen the first ring that sits within the ring of the rangefinder cam. You will be able to screw it back and forth until it reaches the right position for infinity. Hold the ring in position when you tighten the inner ring back.

 

[jc031699]

The helical must be assembled properly of course, but a fine adjustment is possible. On the ring of the rangefinder cam, you see a little hole. This hole was intended for a hook wrench. Of you loosen the first ring that sits within the ring of the rangefinder cam. You will be able to screw it back and forth until it reaches the right position for infinity. Hold the ring in position when you tighten the inner ring back.

OK, amazing. Thank you so much. You saved me so much work.

What a special design for the era, an adjustable cam. The same type of design as my 7artisans 35/1.4, modern day.

As it turns out, it was my ignorance that led to the cam going out of spec. Like I said, I didn't know what that rearmost lock ring did. Now I do....😏

Now for the re-shimming event-
@Sonnar Brian, would you be willing to help me with advice on what my next move would be?
The lens is front focusing, and does not have any shims. Am I at the end of the line here?

 

[Valkir1987]

Prewar Fed cameras have a shorter flange to film distance than Leica cameras. It came close to a 'standard' of 28.70 instead of the usual 28.80mm before the war and most post war Fed 1f cameras have a 28.70mm register. The Fed 1g uses 28.80 mm. (most of them come with a coated lens and modern aperture numbers)

When mounted on a Leica (or any LTM standard 28.80mm body) the lens won't reach infinity.

Shims can be added, but if no shims are present you need a lathe to take something of.

 

[jc031699]

Prewar Fed cameras have a shorter flange to film distance than Leica cameras. It came close to a 'standard' of 28.70 instead of the usual 28.80mm before the war and most post war Fed 1f cameras have a 28.70mm register. The Fed 1g uses 28.80 mm. (most of them come with a coated lens and modern aperture numbers)

When mounted on a Leica (or any LTM standard 28.80mm body) the lens won't reach infinity.

Shims can be added, but if no shims are present you need a lathe to take something of.

Makes sense. I think I may be able to take advantage of the adjustable cam, by grinding down the outer barrel of the helical so that the optical unit / inner helical barrel can screw in further. Thankfully these lenses were made to be fully adjustable (presumably to allow tuning to variances in the flange to focal plane distances in individual cameras): The focus ring is also infinitely adjustable without needing to have new taps made for the grub screws. I need to think this through carefully to make sure that I can get the helical entry points correct though....

Update: After adjusting the cam to make the rangefinder match for wide open close focus, I was able to accurately focus all distances up to infinity even though the cam does not drive the rangefinder far enough. I am thinking that it is the f6.3 maximum aperture that makes this work out. I am open to further suggestions!

I read but cannot currently find where Brian Sweeney had said that the Jupiter-11 (135/4) LTM worked fine on Leica cameras, where as the Jupiter-9 LTM (85/2) does not. I was surprised to learn that after knowing about the Jupiter-9, but perhaps the f4 max aperture effect is similar to what I've seen here with the FED 100/6.3.

 

[Valkir1987]

That looks quite well for a start. It can be a bit soft wide open still.

One of my 100mm Fed lenses came close to infinity on my Leica IIIa. Taken on Provia 100f. I used a Canon hoe shoe finder for the shot, but there was a mismatch in the parallax correction.

 

[jc031699]

Thanks so much for sharing your knowledge and thoughts. In the closeup wide open shot I can see individual pixels, which implies the resolution is high. However it still looks soft, which in these vintage lenses like Summar and Summarit I have seen some say perhaps it is low contrast and aberration that gives this impression.

 

[Sonnar Brian]

The J-11: the minimum focus is ~6ft, and max aperture is F4. I used one mount for a CZJ 13.5cm F4 Sonnar conversion, and shimmed a J-11 for Leica.
The Minimum focus distance is the issue for the J-9 LTM.

 

[jc031699]

I tested this lens with my Techart EA-7 on the Sony a7ii. It was sharper at infinity than when using it on my M240.

I did not feel like I was getting close enough to infinity, so I did grind down the outer helicoid barrel some. This gave new insights into the construction, as taking out the little screw on the side of the lens barrel allows me to unscrew the helicoid without having to undo any other parts. This may have given me a different entry point on the helicoid, but it doesn’t matter because the helicoid goes all the way down to the infinity stop with all entry points. I did have to adjust the cam again for near focus, probably due to this. The rangefinder is still off, but it will probably be sufficient for film and using the digital eyepiece viewfinder / live view for my M240. Not sure if shortening or lengthening the distance between lens groups would help this any.

 

[jc031699]

Here is where I ended up after grinding down the outer barrel so that I could screw the helicoid in about 1mm further toward infinity. I didn't want to go further because it would make the middle distance (~5m) back focus too much, since the helicoid is screwed all the way in even for that. I set the cam to make close up just a tiny bit biased toward front focusing to compensate. The image without the tree is f6.3, the image with the tree is f9. Pardon my sensor dust, I've been tuning a few lenses.

 

[jc031699]

 

[jc031699]

Circling back one more time-
When I was working on this lens previously, I was pretty flummoxed by the consistent circle of flare (like a spotlight in the center of the frame) any time I would stop down past f9. Looking inside the barrel from the rear of the lens, I saw that there was a lot of light scattering around the inside of the barrel, which makes sense since longer FL lenses have larger image circles. I had previously blackened all of these surfaces with india ink, but I have seen a few times recently where that was insufficient.

After finishing a major work project, I took a little reprieve and replaced the india ink with Maxx Darth black acrylic paint on the inner rear barrel. I left the areas inside the aperture and lens unit with india ink as before, not wanting paint flakes inside the optics. This fixed it entirely, even when pointed directly at a kitchen overhead lamp.

When looking at the inside of my Elmar 9cm f4 LTM, the inner rear barrel is similarly blacked out with matte paint.

All AFTER at f12.5. Dramatically improved contrast, no flare. I didn't take a before at higher f-stop

 

[jc031699]

Here is a BEFORE at a larger aperture, f9. The circle of flare is subtle but visible.