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Juha Mattila

Cooke Speed Panchro cement separation issue

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Hello all,

I have this ser II Cooke and it has a separation issue on back element. I wonder how hard is it to fix it? I will take it to local repair shop so they take can take a look but I heard that these old hand build lenses can be tricky to put together again. One repair man already told it wont bee worth it to trye.

 

What do you guys think is it worth it to try to fix this lens? If anyone can give me any advise on this it would be appreciated.

- Juha

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Hello,

 

I had great experience with Focal Point Inc (http://www.focalpointlens.com). They fixed coating issues on a Kinoptik 75mm and cleaned it completely.

 

I found their service pretty affordable too. Just make sure your customs paper are right so you don't pay fees at import afterwards.

 

All the best,

 

Olivier

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Separation is unsightly but usually it doesn't really affect the image, so I wouldn't waste money repairing it if it's just for your own use. If you want to sell it then it might be worth repairing, but make sure you don't spend more than you recoup.

 

I'm sure Focal Point would do a good job, but you could also ask some closer repair places in Europe. Try Gecko Cam or P&S Technik or maybe True Lens Service in the UK.

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Thank you Dom! It will be my own use. The guy how told me it's not worth it, told me also that it might not affect too much the image, but I have notised that if I use bright practicals or let the back light go in to the lens I get pretty bad flare all over my image. I don't have other Cooke but I have Zeiss Sonnar 85mm and I know Zeiss is more contrasty lens but there is so big differens with these lensen even when there goes no light towards the lens. Zeiss seems lot sharper too. Sure Zeiss is sharper by default I didn't think it would be that much. Maybe I should test with other Cooke then I see how much there is differens and would it be worth to repair it.

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Well it might be adding some flare if the separation is more than just at the edges, but they are old lenses with simple coatings, very different to any Zeiss from the last 40 years. If there is coating damage to the front or rear element surfaces or the elements in the iris cavity or shiny iris blades that could also add some flare. You could compare to another Speed Panchro for sure to get a sense of it.

 

It's not a really big job to separate and re-glue a doublet, and older ones tend to be easier to separate than newer ones. Any company that does Speed Panchro re-housings will have come across this before, maybe ask P&S Technik what they think.

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P+S Technik in Germany and TLS in the UK do vintage Cooke lens rehousing as mentioned above, so will be well up to date on repairing these lenses. A separation of an old-school canada balsam bonded doublet is a less painful repair than separation or degrading of the bond done with modern UV cure optical cement.

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Yes, the separation covers about 70% of the lens, including center. Rear elements are in good condition. Lens is also pretty yellow too I don't know is it because of Canada Balsam or radioactivity. I haven't try UV-light treatment yet.

I emailed P&S too.

There is one guy here in Finland how has some experience re-cementing still photography lenses. I wonder is there some special centering and collimating tools and knowledge needed when dealing Panchros whitch differs ordinary still lenses?

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No, optics are optics. Cine lenses might often have tighter tolerances, but the process for splitting and glueing doublets is the same.

 

The yellow comes from the glass, I believe P&S Technik have a heat treatment cure that can remove some of it.

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