Modifying the Collapsible Industar-50 for the Leica

[Brian]

I've wanted one of these for a long time. Collapsible I-50, a Tessar formula lens reforumlated 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.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2792

[Brian]

BUT, the Collapsible I-50 is "just Pretty", oh- I mean Compact.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2793

And the focus was WAY off. At 5M on the RF, actual focus was 3m.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2795

[Brian]

First Step: remove the light baffle at the rear of the lens tube.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2796

I use a pair of Pliers for expanding cotter pins.

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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.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2798

[Brian]

Retaining ring out.

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Set Screw out.

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Optics module pulls out now.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2801

[Brian]

Heart of Brass.

And you can see the seat for the Shim. The one that we need to thicken.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2802

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.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2803

[Brian]

I cut thin strips of copper tape, build up on each side to be symmetric. This job required 3 layers of tape.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2804

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.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2806

[Brian]

Close Focus was good.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2810

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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.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2812

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.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2813

[Brian]

I'll be uploading some distance shots with the M8, they looked much better at infinity with the files-down ring.

[Brian]

Close-up at F3.5

http://www.ziforums.com/picture.php?albumid=256&pictureid=2815

Distance with the new infinity setting.

http://www.ziforums.com/picture.php?albumid=256&pictureid=2816

[Nooky]

Is there a deer in the distance?

Brian, thanks a lot for this tutorial. I might want to try my hand on one of these lenses now that I see how it's done.

[Brian]

Yes, just posing for me. It's something to loo out in the backyard and see the deer at rest. Not tame by any means, but calm. The younger ones even get curious when you approach, but Mom warns them off.