I've wanted one of these for a long time. Collapsible I-50, a Tessar formula lens reformulated with newer glass. The Rigid I-50, more common- but not as pretty. Oh. I mean Compact.
The I-50 Rigid is made of aluminum. This Collapsible I-50 is made of Brass, nicely chromed, and -unlike the Elmar- has an easy to use aperture ring.
BUT: it is made to the Contax standard, and had some problems with a M-Mount adapter. The Tab jammed well before infinity, even on the adapter with the cut-out for collapsible lenses. Shim and FIle.
Start: The I-50's in there various forms. All have the same optics module, use the same size shims.
The I-50 Rigid is made of aluminum. This Collapsible I-50 is made of Brass, nicely chromed, and -unlike the Elmar- has an easy to use aperture ring.
BUT: it is made to the Contax standard, and had some problems with a M-Mount adapter. The Tab jammed well before infinity, even on the adapter with the cut-out for collapsible lenses. Shim and FIle.
Start: The I-50's in there various forms. All have the same optics module, use the same size shims.
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BUT, the Collapsible I-50 is "just Pretty", oh- I mean Compact.
And the focus was WAY off. At 5M on the RF, actual focus was 3m.
And the focus was WAY off. At 5M on the RF, actual focus was 3m.
First Step: remove the light baffle at the rear of the lens tube.
I use a pair of Pliers for expanding cotter pins.
Next, remove the retaining ring for the optics module. I used fine-tipped needle-nose pliers and a spanner. Needle nose to start, spanner after the slots cleared an inner retaining ring.
I use a pair of Pliers for expanding cotter pins.
Next, remove the retaining ring for the optics module. I used fine-tipped needle-nose pliers and a spanner. Needle nose to start, spanner after the slots cleared an inner retaining ring.
Retaining ring out.
Set Screw out.
Optics module pulls out now.
Set Screw out.
Optics module pulls out now.
Heart of Brass.
And you can see the seat for the Shim. The one that we need to thicken.
I did not have a proper shim to get the focus correct, so will use Copper tape to build up the existing one. The through the lens viewer makes life easy, you can use ground glass for film with tape over it at the film gate of your camera. For digital, you can pixel peep.
And you can see the seat for the Shim. The one that we need to thicken.
I did not have a proper shim to get the focus correct, so will use Copper tape to build up the existing one. The through the lens viewer makes life easy, you can use ground glass for film with tape over it at the film gate of your camera. For digital, you can pixel peep.
I cut thin strips of copper tape, build up on each side to be symmetric. This job required 3 layers of tape.
Shim back in, required going in edge-wise, then rotating in the tube. Optics module on the shim, a little buit of a trick to tighten it in, drill out the new tap for the set screw, and get aperture to line up with the index mark. I used the rubber cork to grasp the module while tightening the retaining ring. Then drilled out the tap for the set screw, put the set screw in, and finished tightening.
Shim back in, required going in edge-wise, then rotating in the tube. Optics module on the shim, a little buit of a trick to tighten it in, drill out the new tap for the set screw, and get aperture to line up with the index mark. I used the rubber cork to grasp the module while tightening the retaining ring. Then drilled out the tap for the set screw, put the set screw in, and finished tightening.
Close Focus was good.
But the lens could not go to infinity. The lens screwed in too far on the adapter, past the cut-out of the ring which is intended for the collapsible Elmar. ALSO: the lens is shimmed for close-up, and infinity focus could not be reached. I filed the tab of the focus ring down.
To take the helical apart, take off the close-focus stop screw. The helical easily comes apart. There are multiple starting positions, so REMEMBER where the lens separates so you can restart it at that point.
Once back together, the screw sets infinity, and it is just beyond where the Tab would normally stop it. It goes slightly past infinity, which is perfect for use on a Leica.
But the lens could not go to infinity. The lens screwed in too far on the adapter, past the cut-out of the ring which is intended for the collapsible Elmar. ALSO: the lens is shimmed for close-up, and infinity focus could not be reached. I filed the tab of the focus ring down.
To take the helical apart, take off the close-focus stop screw. The helical easily comes apart. There are multiple starting positions, so REMEMBER where the lens separates so you can restart it at that point.
Once back together, the screw sets infinity, and it is just beyond where the Tab would normally stop it. It goes slightly past infinity, which is perfect for use on a Leica.
Close-up at F3.5
Distance with the new infinity setting.
And pretty colors.
Distance with the new infinity setting.
And pretty colors.
raytoei@gmail.com
Veteran
wow! that I-50 looks familiar 
newspaperguy
Well-known
Nice Brian.
(See you caught that doe again.)
Did you make that viewer?
(See you caught that doe again.)
Did you make that viewer?
Thanks all, Yes- the one and same I-50.
The viewer was a $15 Ebay find of an "I don't know what this is, but I am selling it anyway".
The viewer was a $15 Ebay find of an "I don't know what this is, but I am selling it anyway".
Robert Lai
Well-known
Wow, this is impressive. I had FEDKA adjust an Industar-50 to work with my Leica (and had my FED-2 adjusted at the same time to correspond). Afterwards, the lens worked great on a Leica, but on the FED-2, the infinity lock screw kept scraping the paint on the metal surround around the lens mount of the FED-2. I thought about just getting rid of the infinity lock, but instead I sold the lens. Maybe I should have done something about that screw instead!
ray*j*gun
Veteran
Brian, in your original post you noted that the I 50 collapsible was made to the Contax standard ..... I am confused (so easily happens these days). How is Contax related to LTM lenses?
Thanks!
Thanks!
typhillips
Established
Nice. I did the same thing with my collapsible I-50 so it would work properly on my IIIf. I didn't have the infinity focus problems that you did, though, at least as far as I can tell.
One of your posts also helped me properly shim a J-8, which now focuses wonderfully on the Leica. Just as you said, I had to shim for proper focus at 3m. After that everything fell into place.
These Russian lenses are just fantastic for the money, as long as you aren't afraid to tweak.
One of your posts also helped me properly shim a J-8, which now focuses wonderfully on the Leica. Just as you said, I had to shim for proper focus at 3m. After that everything fell into place.
These Russian lenses are just fantastic for the money, as long as you aren't afraid to tweak.
johannielscom
Snorting silver salts
If I got it correctly, the Russians copied the contax standard when they took Carl Zeiss equipment and technicians as damage payments after WWII. Before that, most of the Russian lenses were not standard at all, but made to fit individual bodies.
The Leitz standard is 51.6mm, the Contax standard is 52.4mm, but known to be 'off' up till 52.6mm. As a result, the lens has a minute difference in helical threads and Russian lenses often do not focus correctly on Leitz bodies. When stopping the lens down, the difference can be negligible, but when shooting wide open and close up, a Russian lens on a Leitz body will front focus if not corrected.
Correcting the lens for wide open and close up will cause slight problems with infinity focus, but these generally can be overcome by stopping down at infinity, usually up to f4.0 possibly f5.6.
Brian really is the expert on this, as you can obviously tell from that very nice pictorial of his!
The Leitz standard is 51.6mm, the Contax standard is 52.4mm, but known to be 'off' up till 52.6mm. As a result, the lens has a minute difference in helical threads and Russian lenses often do not focus correctly on Leitz bodies. When stopping the lens down, the difference can be negligible, but when shooting wide open and close up, a Russian lens on a Leitz body will front focus if not corrected.
Correcting the lens for wide open and close up will cause slight problems with infinity focus, but these generally can be overcome by stopping down at infinity, usually up to f4.0 possibly f5.6.
Brian really is the expert on this, as you can obviously tell from that very nice pictorial of his!
gerbilthemistake
Well-known
I tend to break anything I try to fix, Brian you seem to know how to fix or work around anything, do you happen to offer repair or modification services?
ray*j*gun
Veteran
Thank you Johan..... I see what Brian means now. I was thinking it had something to do with Contax mount lenses.
I have a really nice prewar Fed 3,5 collapsible (uncoated) that I only use on my Zorki 3. Got it from Fedka a while back......therefor I am assuming if I used it on my Barnacks or M's I would have a focus problem.
I also am all thumbs (see gerbilt's question)
Thanks.
I have a really nice prewar Fed 3,5 collapsible (uncoated) that I only use on my Zorki 3. Got it from Fedka a while back......therefor I am assuming if I used it on my Barnacks or M's I would have a focus problem.
I also am all thumbs (see gerbilt's question)
Thanks.
john neal
fallor ergo sum
Brian,
Does this mean it won't work properly on a Fed or Zorki any more?
Does this mean it won't work properly on a Fed or Zorki any more?
John- after shimming for the Leica, it will slightly front focus on Russian cameras. I adjusted the RF of my Zorki 3M to work with the Leica lenses.
Johan is correct about the focal length for the FSU lenses, they are slightly longer than the Leica standard. With Russian lenses that mave rotating cams, it would be possible to cut an "index" into the cam to correct the difference between the FSU standard and the Leica rangefinder. Roland did this with a Contax to LTM adapter. The same could be done for an I-50 or late J-8. It means filing the cam down by 0.1mm at closest focus. The distance scale would be off. I have not done this, and find shimming the simplest approach.
I am a kitchen table hobbyist, FORTRAN programmer by trade. If a software guy can do this, anyone can.
Johan is correct about the focal length for the FSU lenses, they are slightly longer than the Leica standard. With Russian lenses that mave rotating cams, it would be possible to cut an "index" into the cam to correct the difference between the FSU standard and the Leica rangefinder. Roland did this with a Contax to LTM adapter. The same could be done for an I-50 or late J-8. It means filing the cam down by 0.1mm at closest focus. The distance scale would be off. I have not done this, and find shimming the simplest approach.
I am a kitchen table hobbyist, FORTRAN programmer by trade. If a software guy can do this, anyone can.
-doomed-
film is exciting
Perhaps Ill keep my IIIf and grab an industar 50 collapsible for it , though my luck with fsu lenses on leica bodies has been pretty good as I rarely focus wide open and close up , but on the few I have done so with theyve been pretty good. I am glad that Brian does these sorts of diy walkthroughs, for I am sure one day I will get an FSU lense that doesnt work acceptably.