Leica Jupiter-8 50/2 late version, Modified for close-focus.

I figured out an easy way to modify this lens for close focus, after separating the helicals remove the infinity stop screw from the portion with the focus ring, then misthread when putting back together by 1 notch. The close-focus stop will now act as a near and far stop, meaning you get almost 1 full rotation for the focus. The focus ring and DOF scale can both be repositioned.


On the Leica M8,

The normal 1m close-focus:

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L1016242
by fiftyonepointsix, on Flickr

0.65m on the M8
17920415424_ab11a13e29_o.jpg
L1016243
by fiftyonepointsix, on Flickr

Wide-Open at F2.
 
Also F2, a some direct sunlight.

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L1016254
by fiftyonepointsix, on Flickr

I shortened the focal length on this lens, moved the rear module in ~0.5mm or so. The shim was originally 1.3mm, and it was off by ~0.15mm. If I was not going to mod for close-focus, would have been good enough to add the extra shim. Moving the rear module closer to the front acts like thickening the shim and simultaneously shortening the focal length. The latter brings it closer to the Leica standard- needed to maintain focus over the increased range.

Looking at the pictures, filing works out once again.
 
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They look good to me!

It's nice to know that out two M Monochrom's agree on RF calibration!

KMZ J-8's are all good. This one has the rear group moved in to bring closer to the Leica standard, and the helical is purposely misthreaded to eliminate an internal stop screw and allow close focus to ~18". RF cam keeps up to ~0.65m.
 

asiafish

All-Pro
Location
Bakersfield, CA
Real Name
Andrew
They look good to me!

It's nice to know that out two M Monochrom's agree on RF calibration!

KMZ J-8's are all good. This one has the rear group moved in to bring closer to the Leica standard, and the helical is purposely misthreaded to eliminate an internal stop screw and allow close focus to ~18". RF cam keeps up to ~0.65m.

Even nicer to know that my new Monochrom focuses the same as my old one. I really like this lens. The aperture ring is very loose, but four is decent and image quality looks great to me.
 
This lens is one of a kind. I disassembled it, polished down the barrel to move the rear group in closer to the front section to shorten the focal length. The helical is intentionally misassembled to allow one stop screw to be used for both infinity and close focus stop. The threads of the mount are filed down to allow RF coupling to ~0.65m. The DOF ring, Focus ring, and aperture ring are all re-indexed. I used to be a rocket scientist. Worked on spaceborne sensors and writing software to calculate and optimize orbits, so that counts. Adjusting Jupiters is not rocket science, but I did learn a lot about lenses on the project. So it did not hurt to be a rocket scientist.
 

asiafish

All-Pro
Location
Bakersfield, CA
Real Name
Andrew
This lens is one of a kind. I disassembled it, polished down the barrel to move the rear group in closer to the front section to shorten the focal length. The helical is intentionally misassembled to allow one stop screw to be used for both infinity and close focus stop. The threads of the mount are filed down to allow RF coupling to ~0.65m. The DOF ring, Focus ring, and aperture ring are all re-indexed. I used to be a rocket scientist. Worked on spaceborne sensors and writing software to calculate and optimize orbits, so that counts. Adjusting Jupiters is not rocket science, but I did learn a lot about lenses on the project. So it did not hurt to be a rocket scientist.

It is an exceptional lens. I followed your advice and put a little scotch tape in there and now the aperture ring move gently, but stays put. I can see this one getting a lot of use.
 

dante

Rookie
I never really hit a bad 50/2. The black-paint ones freaked me out, but the lens has a pleasant look, even unmodified. This was on my Hexar RF.

Dante
 

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The DOF at F2 is enough to cover the difference between focal length between the Leica and Zeiss standard at 1m. Going down to 0.65m required the change.
 

asiafish

All-Pro
Location
Bakersfield, CA
Real Name
Andrew
The DOF at F2 is enough to cover the difference between focal length between the Leica and Zeiss standard at 1m. Going down to 0.65m required the change.
Well it definitely worked. It's a strange looking lens watching the focus distance markings pass infinity and mfd, but it is accurate at all distances at f/2 to the rangefinder (not the scale).
 

helinophoto

Rookie
You can put some scotch tape between the aperture ring and focus mount to get extra friction- it works.

In my own trials, I've found that lithium based bike-grease does wonders for the aperture-ring. I found it to be too thick for the helical,so i smeared some of it for the aperture and the aperture is now buttery smooth and perfectly "sticky".

(This: Not sure where else it exists but at least there is a photo of the tube Zéfal Pro II Grease sykkelfett - ZEFAL | Clas Ohlson )
 

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