Ages ago, I bought a broken Yashica GSN as a parts camera to repair the rangefinder mechanism on my keeper GSN. (You can read about that surgery here.)
When I cannibalized the parts camera, I took the lens off (probably the only part of that camera which was in decent shape) hoping to one day adapt it for use on a Leica M body or something similar. Well, the lens wound up, like a lot of my projects, kicking around in a drawer for years and just gathering dust. Then the NEX series of cameras came along and with them adapters for every lens imaginable. Slooowly, eventually, the dim flashbulb in my head went off, I remembered the long forgotten GSN lens and I got to wondering if and how I could pair it with my NEX 5n.
My main issue always came down to how to focus this little beastie. When I had removed the lens from the GSN, along with disabling the shutter and fixing it in the open position, I removed all the of the focusing mechanism and filed down the lens mount flush with the helicoid. (The holes seen were for wires and a metal rod that triggered the shutter inside the lens.)
In hindsight, I should have obviously left at least a part of the focusing hardware in place, so at this point whatever was going to focus this lens was going to have to be an external thing.
This is where one of my favorite adapters for the NEX series of cameras comes in; Sony E-mount adapters that have a helicoid built in, which are meant to allow for close(er) focus with M-mount lenses. These adapters have gotten dramatically cheaper as more Chinese made versions have become available. If you search eBay for “nex helicoid” you will find plenty in the $35-$40 range, which is likely the same as the one I have. There is even one that goes for about $18 that can be found by searching for “tinray helicoid”.
At the moment, and as you can see from the photos, this is in the prototype stages, and I am simply using blu-tack to fix the lens to the adapter. I was actually lucky to have removed as much of the focusing mechanism as I did because in this setup with this particular helicoid adapter infinity focus is very close to spot on. It currently focuses just a little bit past infinity, but I plan to shim that when I do the final mounting.
The only tricky bit has been to tripod mount the camera and check the focus in the corners to ensure that the lens is fairly aligned with the sensor. Of course, this being blu-tack, it is as easy to push and prod the lens in to a rough alignment as it is to knock it right back out. 🙄
Eventually, I want to get a Hawks v3 helicoid adapter (much better quality!) for use on my a7R. I will then use some JB Weld on this adapter to permanently fix the GSN lens to the helicoid. I’ll update this page when that happens.
In the meantime, here is a sample shot with the prototype mounted GSN 45mm f/1.7 lens shot at f/5.6 on a Sony NEX 5n. (click on the image to see it full size)
Years later… I finally got around to permanently attaching the lens to the adapter. The most critical part of the process is making sure that the adapter is not out of tilt with the lens. To do this, I placed the lens front side down, added a pretty thick layer (2-3mm) of JB Weld to the adapter ring, and placed the ring on the lens. Then I let it settle for a bit, and allowed the JB Weld to firm up a little. Then I checked the tilt by rotating the lens around to see if any side was lower, and making small adjustments to the adapter until I was happy with the result. I was also careful to align the lens and adapter, so the top of the lens is facing up when clicked into place on the camera.
The JB Weld has held up very well over the years, and the mounting to the adapter is very solid. The aperture ring works and I can still manually adjust the aperture from f/1.7 to f/16. I left the self-timer in place, so you can still pull the lever, but it doesn’t click into place now and will just unwind itself. I set the focus ring on the lens to infinity and that part doesn’t move anymore. If I was to re-do this, I would probably set the focus ring to the middle of the scale so that the lens grips would be on each side of the lens instead. This wouldn’t change the focus in any way, it would just make it look a bit better.
Here are some recent shots I took with this lens and a Sony A7IV:
Here are some Yashica related links that helped me with this project:
Yashica GSN service/repair manual:
https://archive.org/details/nat-cam-yashica-electro-35-repair
Forum post with instructions on how to remove the lens from the camera:
https://www.dyxum.com/dforum/yashica-35-lens-conversion_topic110776.html
Mike Lee has a great write-up for adapting a GSN lens to the Sony E mount:
https://mike-lee.org/scripts/camera/view.htm?id=1649
Page showing how to get to the aperture and shutter blades from the front of the lens:
https://ctm35.wordpress.com/2017/02/22/yashica-electro-35-gsn-lens-disassemblyrepair/
Hi! Great project, I would like to do the same. Do you have some instructions or guides? I picked up a Electro 35 at a local thrift (had no idea what to do with it). I have a few E-Mount cameras and I think it would be a fun project. If you got anything you can forward or would be willing to walk me through some of it that would be awesome.
Cheers,
Chris
Hi Chris,
I don’t have instructions on how to take the GSN apart on my page but you can find great disassembly and repair info at the following links:
http://www.yashica-guy.com/document/repair.html
http://www.yashicaddiction.com/
Let me know if you get stuck or have any questions…
Hi!
I’m in the midst of the same project as you. I have removed the lens from a broken Yashica GX, the next step i to lock the copal shutter open but I’m not sure how to get at it.
Did you remove any lensgroups? If so, from the front or back?
Hi Jesper! You’ll need to go in from the front of the lens to get to the shutter. It’s been a while since I did this but IIRC once you get the front elements out the shutter and timer mechanics will be exposed. It’s fairly simple to block the shutter in an open position. On the back end of the lens I cut the wires, the shutter cocking rod and filed the lens mount down to make it flat and even.
Hope that helps! Let me know if you have any other questions.
So you say, “I was actually lucky to have removed as much of the focusing mechanism as I did because in this setup with this particular helicoid adapter infinity focus is very close to spot on. It currently focuses just a little bit past infinity but I plan to shim that when I do the final mounting.”. How did you finally shim it to get proper focal length?
Hi Mark. I’m little ashamed to say, I never bothered… I did eventually JB Weld the lens to the adapter and it came out well. But it was focusing past the infinity point by so little that I didn’t bother. If I was to bother, I would have needed to take off a bit more from the back of the lens to bring it in to the adapter more. But again, it was no nearly spot on that it wasn’t worth the effort.
Hi, and thanks for sharing this. As for the helicoid adapter, which one do you recommend, the m-mount helicoid for Leica? Thanks in advance.
Marlon
Hi Marlon! That is correct. I used a Leica M mount to Sony EF helicoid adapter. For this project, I just got a cheap one on eBay. Search for “Leica M to E mount Sony Adapter Helicoid”. The cheapest ones seem to go for around $25 and work create for adapting old lenses like this. The most critical thing is getting the lens centered and flat/perpendicular with the adapter. That is why I originally used blue-tack. I was not confident I’d get a permanent bond right. In the end I used JB Weld and it did work out though. It is still a great lens. 🙂
As for a really great helical adapter, I’d recommend the YEENON M-E Helicoid Adapter. I have been using one for years on my A7 and have had zero issues. Really solid adapter.
Well, I ordered the helicoid adapter from a vendor in China. While waiting, I looked you up at the Flickr website and subbed you. I’m there as well, at:
https://www.flickr.com/photos/3flyte/
I completed it several hours ago (748p.m.), using fast-setting JB Weld. I put it on my a7II, powered it on, and it works perfectly. It focuses closer than it did as a rangefinder lens at about 18 inches. It will focus to infinity, I’m sure, maybe beyond. I’ll make sure tomorrow when there’s light. Thanks to your blog-tutorial, you made it all possible. And thanks for meeting up with me on Flickr =) Cheers;
Marlon
That is great! Mine focuses a little past infinity as well, but it doesn’t bother me at all on the A7. The image quality and rendering from this lens still surprises me. Really happy to hear there’s another one out there that has been given a second life! See you on flickr! 🙂