HELP | Bronica GS1 100mm f3.5 lens - Separating or Something Else?

ozphoto

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Good afternoon brains trust!

I'm in the process of sorting out my Bronica GS1 to part out and noticed that my 100mm f3.5 lens has some weird banding along one edge. It's not a reflection and can be seen less obviously when the front cap is off, but there are definitely two "rainbow" bands present.

Is this lens separation or something else entirely? I've never experienced this with any other gear, so it has me rather stumped . . .

 

voceumana

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Maybe the lens was cleaned with fluid applied directly on the lens and it seeped inside. Lenses should always be cleaned with the fluid applied to the cloth or tissue to avoid this.
 

Kino

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Yes, lens separation.

While it certainly impacts resell value, it might not drastically the image being formed.

The only way to know is to use it...
 

Dan Fromm

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Newton's rings. As Kino aid, separations. I have a Kodak 25-15 w/a adapter for a 25/1.4 Cine Ektar with terrible Newton's rings. They're visible in the finder and on film. Its toast.

Mount your lens on the camera and try to see the rings in the finder. If you see them, its toast. If not, test with film.

About toast. I've seen suggestions that separations like yours can sometimes be fixed by putting a drop of oil on the edge of the separated element and letting capillary action wick the oil into the gap.
 
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OP

ozphoto

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Thanks, Dan. I'll check it out tomorrow. Re the oil method - think I might leave that to the more technically minded; knowing my luck I'll probably make it worse.
 

craigclu

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One of my 100's that I got some years ago with a system purchase has the same look to it. I've not used it as I assumed it wasn't usable. I should give it a try as it might have an interesting effect? It's curious that this is also a 100mm.....

 
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ozphoto

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Interesting. I have used mine in the past and it was fine - I don't remember seeing the separation previously, so it is a more recent issue. Shall test next week and post the results for you.
 

btaylor

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Yes, looks like separation. Sometimes it has no noticeable affect on photos. Unfortunately it drops the monetary value to next to nothing, especially on a common focal length like the 100mm.
 
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