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Need help with dissassembly of a lens group
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PostPosted: Sun Oct 12, 2014 4:31 pm    Post subject: Need help with dissassembly of a lens group Reply with quote
Hello,

I am trying to dissassemble an A.Schacht Ulm R Travenar 2.8/85.

Actually I want to clean the back of the 2nd front glass.....I have taken apart the lens all the way down to the component consisting of the 2nd and 3rd glasses......

I have no idea of how to take the glasses out.....I see the only movable part of this component is the black plastic-like ring as circled on the picture below............but it can be turned forever without coming out.....doesn't seems to be a screw threaded structure.

Could anybody give me your kind advice? Thanks a lot.



PostPosted: Sun Oct 12, 2014 4:39 pm    Post subject: Re: Need help with dissassembly of a lens group Reply with quote
The 2nd and 3rd of the 2.8/90 are cemented together. I am not sure if your 85mm are sharing the same optical formula.


PostPosted: Sun Oct 12, 2014 4:43 pm    Post subject: Re: Need help with dissassembly of a lens group Reply with quote
calvin83 wrote:
The 2nd and 3rd of the 2.8/90 are cemented together. I am not sure if your 85mm are sharing the same optical formula.



Hello Calvin,

Thanks for your reply. I see that there is a fungus like spot on the glass....that's why I want to clean it. If this 85 is cemented together...would it be possible to have fungus on the cemented surfaces? I am no expert of this.......

and even if they are cemented together......would it be possible to take the whole group out from the container?


PostPosted: Sun Oct 12, 2014 5:05 pm    Post subject: Reply with quote
For confirmation, you may post some photos from different angles showing the spot.

You can check if the elements are glued/cemented by counting the reflections. If there is four strong reflections, it means there are two separate glasses separated by air. If there is two strong reflections and one weak reflections, it means the two element is cemented and the weak reflection come from the cemented surface.


PostPosted: Mon Oct 13, 2014 1:26 am    Post subject: Reply with quote
calvin83 wrote:
For confirmation, you may post some photos from different angles showing the spot.

You can check if the elements are glued/cemented by counting the reflections. If there is four strong reflections, it means there are two separate glasses separated by air. If there is two strong reflections and one weak reflections, it means the two element is cemented and the weak reflection come from the cemented surface.


Sorry I'm not able to take a shot of the spot since I have no digital camera with me right now...but I used a 10x loupe to examine the spot and found a node/cell surrounded by a petal-like line....it seems to be 99%, if not 100%, organic...

Regarding the reflections, I shined a torch light from the 2nd glass through the 3rd glass.....I observed from the 2nd glass side and saw 3 reflections of the light......the weakest one is at the front........

Do you have any advice? would it be possible to press the 2nd glass and pop the group out? Thank you very much


PostPosted: Mon Oct 13, 2014 2:54 am    Post subject: Reply with quote
tales87 wrote:
calvin83 wrote:
For confirmation, you may post some photos from different angles showing the spot.

You can check if the elements are glued/cemented by counting the reflections. If there is four strong reflections, it means there are two separate glasses separated by air. If there is two strong reflections and one weak reflections, it means the two element is cemented and the weak reflection come from the cemented surface.


Sorry I'm not able to take a shot of the spot since I have no digital camera with me right now...but I used a 10x loupe to examine the spot and found a node/cell surrounded by a petal-like line....it seems to be 99%, if not 100%, organic...

Regarding the reflections, I shined a torch light from the 2nd glass through the 3rd glass.....I observed from the 2nd glass side and saw 3 reflections of the light......the weakest one is at the front........

Do you have any advice? would it be possible to press the 2nd glass and pop the group out? Thank you very much

Move LED around the lens and observe from different angles. If you can confirm there are only three reflections, the elements are cemented together. I heard it is possible for fungus to growth inside the elements.

You can try to push from the side with black plastic-like ring. However, you cannot clean the fungus if it is cemented without re-cementing the elements.
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