Flipping a Yashica mat 124G

[Anirudha Ambekar]

Recently, I found and bought a Yashicamat 124G whos lens is not pretty. Is it possible to replace the lens by yourself?

 

[darkroommike]

Well you could replace both the viewing and taking lenses from another similar Yashica with a bad shutter or advance. But you would have to swap the pair not just the taking lens.

 

[GregW]

What's wrong with it? These often have ugly dense haze that is not too hard to clean off.

 

[jspillane]

A word of warning if you undertake a lens swap: if registration of the lenses is off, you can have focus errors with TLR's that can be a little difficult to detect (easiest way is to shoot some close-ups with the aperture wide open). Make sure to double check that the registration is correct.

I haven't done this by hand before, but a good technician should be able to check and shim the lenses accordingly to make sure your taking and viewing lenses match perfect.

 

[Anirudha Ambekar]

I am taking this up as DIY because the local repair shop wrote the lens and the camera off as not worth putting their time into.It doesn't look so bad to me. The shutter fired at all speeds and aperture opens smoothly.
I'll go step by step and clean it completely before swapping any parts.

 

[Nick Merritt]

Shoot a roll of film (use a shade if possible) and see how the results look. You didn't explain what's wrong with the lens (haze? scratches?), but either can largely be overcome with a shade to minimize flare.

 

[Anirudha Ambekar]

I would say it is haze plus cleaning marks. The attached image should give some idea of how it looks. I was pointing the camera at a well-lit white wall with the back open while taking this picture.
By shade do you mean a lens hood?

 

[ic-racer]

I'll put my money on "won't clean off."
Let us know. It is certainly worth your time because you will gain a lot of knowledge about 124G cameras. If the rest of the camera is great, I suspect you can find a beat up camera with clean lenses to use as replacement.

I had some similar projects like that. In this case I swapped all the lens elements from the beat-up barrel to the pristine barrel with the Durst flange. The 'good looking' lens barrel with the Durst flange had lens elements that were destroyed by 'cleaning marks.'

 

[ic-racer]

This was another similar project. A 90mm lens with a special barrel to fit the Horseman 4x5 camera. But it had fungus. I swapped lens elements with a similar pristine lens that had the exact same lens elements (a Caltar HR) but a different barrel.

 

[ic-racer]

I guess I have a third related story. I was given a Rolleicord in 'unused' condition by a friend of the family. However, the taking lens had bad haze. Turns out it DID clean right off! Sometimes you get lucky.

 

[ic-racer]

Ok so one last "Not So Happy" story. I paid fair market value for this large-format teleconverter. That little thing has seven lens elements and 14 surfaces and it was hazy (more lens elements than your entire Yashica lens). However, after total diassembly (a major ordeal) and cleaning, it is still hazy.

 

[shutterfinger]

I've cleaned haze off lens with my breath and a clean Microdear heavyweight microfiber lens cleaning cloth that no lens cleaner or glass cleaner would phase. A heavyweight lens cleaning cloth will feel like flannel, velvet or similar thick material. Microdear makes store brands as well. Dead Link Removed

 

[Anirudha Ambekar]

All in all I would say you have encouraged me to try and salavage the camera despite the last scary story.
The heavy-duty cleaning cloth looks good for the planned cleaning attempt.

 

[Fixcinater]

If you get something soft, like a rubber drain plug, that is the correct size to contact only the front of the lens, you can spin out the front of the taking lens and access the lens elements that face the aperture/shutter blades. These are the ones that generally accumulate haze. I've cleaned Yashica lenses that had so much condensed/off-gassed lubricant that visible droplets were formed. For whatever reason, this haze on the Yashica TLRs generally cleans up, at least to 95% (good for using for real photography at least) and so is worth the attempt.

 

[paul ron]

you can swap the taking lens from another 124. but to refocus the taker to viewer n film plane, you will have to remove the front leather to access the locking set screw of the viewer.

btw... this thread has a nice link to a repair of a D... access to the lenses n shutter is the same for the 124.

(there was a url link here which no longer exists)

 

[Anirudha Ambekar]

Thanks Paul.
Will I have to refocus even if I take it out for cleaning as Fixcinator says?

 

[shutterfinger]

Lens are rarely their marked focal length. They can be .05mm to 5mm either side of the marked focal length, usual is with in 3 mm.
The viewing and taking lens of a TLR are matched for focal length.
The greater the difference in focal length of the view and taking lens the greater the focus error at closer distances.
A.05mm difference may not be noticed until 6 feet or closer where a difference of 3mm will be noticed at 15 to 20 feet.

Unscrewing a lens for cleaning and reinstalling it will not affect focusing unless there are shims under the cell and you leave one or more out on reassembly or if you take the individual elements out then install them reversed in the cell.

This is the lens diagram for a Zeiss 75mm lens, your will be very similar. Light travels in direction of the arrow. The first 2 elements comprise the front cell which unscrews from the front of the shutter. This cell can be further disassembled by unscrewing the trim/nameplate ring from the front of the cell. The next 2 elements are behind the shutter and aperture blades and are cemented together. They cannot be easily separated and should not be separated unless there is a failure in the bonding agent. Special care must be taken when separating cemented lens elements. You may be able to unscrew the rear cell from the shutter with the back open.
The front elements have an air space between them as does the front to rear cell element surfaces, these are the ones that need cleaning. Unscrew the front cell, clean the outside surfaces of both the front and rear cells then if the haze is not gone separate the front cell elements and clean them.

 

[paul ron]

Thanks Paul.
Will I have to refocus even if I take it out for cleaning as Fixcinator says?

probably not but why not check n make adjustments while you are working on it anyway?

 

[Anirudha Ambekar]

So I unscrewed the front cell and both the surfaces on this piece were fairly clean.
I used the bulb mode to look at the other exposed surface (the front surface of the middle element?) and I could see significant "haze" on this surface.
I tried cleaning it with a Q-tip and acetone and then Q-tip and alcohol.
but as ic-racer said, it won't clean off! :-(
What could be the reason?
Do i need to look at the airspace between the two lenses?
Or is their a special cleaning method that I must use?

 

[shutterfinger]

Repeat, post #12.

 

[trythis]

I read on Leica's site about using cigarette ash for polishing. I wouldn't know where to get that type of ash or if it works...just passing on info.

 

[anfenglin]

For surfaces, I also successfully used toothpaste to get rid of the destroyed single coating of a Belar lens on a Flexaret.
The microgranules rub it off just like placque on your teeth.

The other possibility for the remaining haze could be a deteriorated lens cement layer between the last two lens elements.
I've seen this in its beginning stage in Zeiss Jena and Meyer lenses, so in the 35mm Flektogon and the 100mm 2.8 Meyer / Pentacon.
If that's the case in your lens, there is no other option but to throw it away.
Unless of course you want to try to re-cement it. You'd need acetone and either Canada balm or some sort of modern epoxy resin.

 

[shutterfinger]

Recementing lens is not that difficult but requires precision, which is beyond some members. This discussion tells how http://www.skgrimes.com/library/old-news/old-lenses-can-be-restored-by-re-cementing

I had a 12 inch Goertz Dagor with a very hazy cell that was due to cementing failure. I heated in an oven heated to 300°F then put the cell in and turned the oven off. I repeated this several times with no help. I also poured boiling water on it in a container and allowed it to cool to touch, again no help. I put it away and decided to try again 6 months later and the cell was crystal clear.

 

[Anirudha Ambekar]

The combination of toothpaste and heavy microfiber cloth worked! Now I am left with a lens with no haze but cleaning marks. I'll put a roll through it now but I am going to look out for a spare pristine lens that I can swap the current one with.
Thanks everyone for your help!

 

[paul ron]

rouge or rotten stone are the best for polishing glass. they dont leave "cleaning" abrasions.

those abrasions just cause a beautiful soft focus.