Jupiter-8 50mm F2.0 - extending focus to 0.6m (2ft)

yukosteel · Joined: 22 Jan 2018 Posts: 44

Just recently tried this lens and like how it renders on Fujifilm X-T2. I'm using set of LTM to Leica M + Leica M to FX adapter. It is very small lens and pleasant to focus, but by default closest focusing is limited to 1m only.

Here's short article on how to extend Jupiter-8 minimal 1m focus to 0.6m https://yukosteel.wordpress.com/2019/03/09/mod-jupiter-8-50mm-f2-0-focus-to-0-6m/

fiftyonepointsix · Joined: 30 Apr 2017 Posts: 292

https://cameraderie.org/threads/jupiter-8.39524/

To add- if using on a Leica, place the lens on an M-Mount adapter and file down the Threads where the cam of the lens comes into contact with the RF pickup. RF coupling will hols to 0.65m.

I did this a few years ago, ended up selling the lens. It's a neat trick that works only on the later J-8's where the front of the lens rotates with the focus.

Just to add- very nice write-ups on disassembling lenses on your blog.

yukosteel · Joined: 22 Jan 2018 Posts: 44

Thanks for sharing that thread and very useful details on rangefinder couple, I even didn't think about such option.

I also plan to add 0.5mm shims to that long bolts later, because now they are touching each other on minimal focus and there is a risk to accidentally rotate helicoid further while dismounting lens. I think extra 1mm should be enough to prevent that.

fiftyonepointsix · Joined: 30 Apr 2017 Posts: 292

The method I used for the lens in the thread: Instead of removing one of the screws, I "mis-threaded" the helical to reverse the action of the two stop screws. The J-8 in normal position has "about" 120degrees from 0.9m to infinity. Misthreading allows greater motion before hitting the stops. Then- undo the set screws for the DOF ring and focus ring, to re-align with the new position of the helical. The stop screws made good contact.