Yashica GSN Butchery

[Ulfric M Douglas]

I recently bought a knackered old Yashica GSN off e-bay. The body was half-dissassembled and a few bits were missing : Ideal for my evil project. (insert evil laugh)

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For those of a nervous disposition I've thumbnailed the "gory" pictures.
I had to remove 99% of the camera to isolate the lens. It has its front elements removed to give me access to the electronic leaf shutter.

Careful use of Dronco stainless 1mm cutting disc.

Insert hard steel plug (bit off a bit) into in-lens leaf shutter mechanism to jam it open forever.

It is important to grind the camera's front plate to a slim ring enabling focusing.
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At first I made up the mount straight onto my G1 using epoxy putty alone, but wanted one I could mount and dismount...
So I sent off for a C-mount adapter : the only one with a thin enough plate. Bit of epoxy-putty and filing and glueing later.

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Cost : £7ish for Yashica, £13ish for adapter, half a day's work. Enormous satisfaction achieved.
End of story.

 

[robertro]

Yashica GSN...

I have almost done the same, except that I removed the shutter mechanism so it wouldn't get in the way. I am about to attach the lens to the adapter plate - I was going to drill the adapter and use the existing screw holes. I wanted to ask you about spacing (you mention using part of the caera body, if I understand correctly, as an additional spacer) - i.e. how you achieved infinity and how you adjusted as needed.

If you had a photo of the side of the lens that would be great.

I'm currently sitting on a Yashica Lynx 14 IC with a 45mm f1.4 lens that is pending the results of the GSN experiments....

 

[Streetshooter]

That was actually a nice camera. The lens has great sharpness and contrast.
I bought one of them in Nam for my uncle.
He liked RF cameras. I got his M3 and gave him this.
Good luck with your re-creation of a classic camera.
Can't wait to see images youse make.

 

[Gwendal]

First off : thanks for the post - always interesting ! I have a question, though : how can you guarantee there is the right flange distance ?

 

[Brian S]

Good job- I've got some Fixed-Lens cameras and have though of doing this. I have a lot of lenses...

 

[Streetshooter]

Brian,
I'm relieved you posted. You are the Official Camera/Lens fixer upper.
Thanks....

 

[Ulfric M Douglas]

I was going to drill new holes if the glue didn't hold...

... I was going to drill the adapter and use the existing screw holes. I wanted to ask you about spacing (you mention using part of the caera body, if I understand correctly, as an additional spacer) - i.e. how you achieved infinity and how you adjusted as needed....

The camera's front plate (which is NOW the lens' rear plate) has two brass 'tags' in slots in the rear portion of the lens : you turn the focus ring and the helix makes the whole lens move away from/towards the camera body: the alignment is held by the slots and tags. I only have one tag, but that's fine. Because of this the two tags and at least a 'ring' of the camera body front plate must be left intact and becomes the back of the lens assambly.

I then built up epoxy putty around this 'ring' : too much and then careful sanding to slowly get proper focus. The epoxy construction WAS my adapter for a week.

... : how can you guarantee there is the right flange distance ?

That's something I had to do twice. After taking pictures where the lens marking said 'infinity' and the fous was on next door's cabbages ... slow filing and sanding. 0.8m is the close focus mark : easily checked.
For proper alignment I balanced a plate on the camera lens resting on a table and measured around the rim to get it level. It isn't perfectly level but it does focus correctly enough for me.

Sharper than my Russki rangefinder lenses.

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Nice, less flare than some.

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Quite a clear and sharp 100% crop in Whitehaven harbour;

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And, remarkably, very little CA so far ;

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[JoeFriday]

Amazing! A GSN was the very first rangefinder i ever bought. Very sharp lens, but I hated the aperture-priority only setting.

 

[Ulfric M Douglas]

I just found a link to a bloke off the RangefinderForum and his Flickr page.
It shows disassembly differently and with hordes of photos.
Color-Yashinon DX 45mm F1.7 - a set on Flickr

 

[robertro]

45 / 1.7 Yashinon

Yes, I had followed this fellow's instructions to disassemble, and I now have the lens free of the body. It looks very good when I hold it up to my camera by hand, but that's not a long-term solution, and it's not entirely clear to me how the mount is aligned and set to infinity.

From his pics, it looks like he has just drilled the mount and screwed it into the existing holes with no change needed for infinity focus. Since he screwed it into the adapter, I assume he did not have to use the surgically-removed part of the camera body. Very elegant if that's the case.

 

[Ulfric M Douglas]

Well I can't see from the pics how he allows the lens body to slide in and out without turning, or how he shimmed it to the C-mount adapter and adjusted for focus, or exactly what the C-mount adapter is screwed to : which part of the lens assembly. These parts are the hard parts.

 

[jimevidon]

The closer focused pictures are very sharp with good contrast. But the one shot at infinity of the castle is a little soft. Perhaps a little more work on the mounting plate thickness will do the trick? As I recall, my GSN, when it was working many years ago was razor sharp at all distances.
Jim

 

[Ulfric M Douglas]

I'm thinking the light was a bit troublesome at that angle : that ruin doesn't seem to come out well with any camera/lens we've used.
Next job : hood & internal baffle/stops.
More testeeng.

 

[MiniMax]

I just found a link to a bloke off the RangefinderForum and his Flickr page.
It shows disassembly differently and with hordes of photos.
Color-Yashinon DX 45mm F1.7 - a set on Flickr

I was totally amazed to see (for the first time ever) what huge amount of ingenious craftmanship went into these cameras. I would have never thought of this complexity. This was much more surprise than the comparable simple fact, that the better lenses used then still can stand up to modern designs.

 

[Tecpatl4]

I was thinking the same thing myself. I had an Electro-35 I picked up off ebay a few years ago wanting a ranger finder. Turns out it was a basket case, all the solder joints were corroded and I have not the fingers for that sort of work. I stipped the lens down and got all the shutter guts out, but there is one screw that holds the mounting plate on, the screwdriver tip broke off inside there and I can't get it out, I am considering drilling it but will think about it first. If not, the front element would make a dandy loupe for you folks that still do film. The rear one is nice too, but not so large.

I saw three of these things at the antique mall, ranging in price from $20 to $45. Don't do it, They go for ten bucks on ebay.

As for the rangefinder, I ended up with a nice Olympus Trip for 10 bucks. Works just fine.

 

[Ulfric M Douglas]

... I stipped the lens down and got all the shutter guts out, but there is one screw that holds the mounting plate on, the screwdriver tip broke off inside there and I can't get it out, I am considering drilling it but will think about it first. ..

I found that removing the lens from its 'mounting plate' was the opposite to what was needed.
I simply reduced the front plate of the camera - lens attatched - until it resembled a ring of metal, then I could get it to mount into the C-mount-to-m4/3rds adapter.

Yashica Electro GSN is one of the few rangefinders that has a good lens, an F1.7 lens, and is still CHEAP because it was kinda common and breaks down.
I think there's a Canonet that looks the business too.

 

[robertro]

Now you tell me....I have been trying to figure out how to munt the lens so that it allows in/out motion without rotating and have so far been stumped...

OTOH, it works as a nice tilt/shift lens when hand-held in front of the camera body ;-)

 

[Maeda]

...so did you guys make any more progress on this? I broke down and registered to bump this!
Judging by pictures, and that flickr set, the disassembly looks like cake, but how do you go about adapting the flange to the lens body(sans epoxy) and still be able to focus?

I just picked up a 10$ Electro, and a C-mount adapter...

 

[Ulfric M Douglas]

... how do you go about adapting the flange to the lens body(sans epoxy) ...

You need to create the 'flange' from a ring-shaped section of the front plate of the Yashica body which contains the two brass tabs that allow the lens to slide without turning : reduce it in diameter until it will fit into/onto your C-adapter. You can then drill and tap that 'flange' and screw through from the back of the C-adapter.

 

[penfan2010]

Nice job

Amazing work that you did to get the lens adapted to your camera, and the image quality is excellent. You are giving me ideas----a similar Yashica with a damaged shutter sits gathering dust on a bookshelf at home (with the rest of the "not working" vintage cameras), and I just might have a go. Only issue is that it was my father-in-law's main camera for shooting pics of my wife and her brothers when they were growing up----she is quite sentimental and will not look too kindly on her Dad's Yashica being mangled...unless you have any thoughts on how to put a C mount onto the Yashica body as well so I can mount some unused lens on it.:smile: