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Simon Benton
13-Apr-2014, 06:54
I obtained an older 250mm f6.7 Fujinon that has separation on the front and back elements and covers the whole lens. I can remove the elements from the barrel and have heard that if there is a visible crack oil can be applied to fill the separated elements. Can any member please advise of the type of oil I should use and should the whole of the glass be immersed in the oil or do I just apply to the crack with a brush. Any advice gratefully received.

mdarnton
13-Apr-2014, 07:02
Someone will surely say you can do it, and it will be OK, but you might want to consider some of the things that they haven't:

It is probably little understood that oil is a solvent for natural resin. That could make the problem worse, or it could spread to other elements. Not to mention possible migration to the diaphragm, etc., depending on how careful you are and the oil you use. Oil also evaporates over time, so there's the additional problem of it fogging surfaces, more migration, etc.

Haven't a few people reglued their own elements at home? I bet there's a how-to somewhere on the web.

hoffner
13-Apr-2014, 07:12
I obtained an older 250mm f6.7 Fujinon that has separation on the front and back elements and covers the whole lens. I can remove the elements from the barrel and have heard that if there is a visible crack oil can be applied to fill the separated elements.


Sound like a perfect invitation for a fungus to grow on it.

Chauncey Walden
14-Apr-2014, 09:08
Opticon?

mdarnton
14-Apr-2014, 10:04
The barcode scanner Opticon, the contact lens Opticon, or some other Opticon?

Chauncey Walden
14-Apr-2014, 12:57
Opticon resin No. 224. A fracture sealer for gemstones with the RI of quartz.

Tracy Storer
14-Apr-2014, 17:26
Or pack the lens off to Focal Point Lens in Co for recementing. he does a very good job. Separating the elements is the hard part but that's already done !

Steven Tribe
15-Apr-2014, 00:58
Sorry, but you will have to describe/image separation!

Is is just regular Newton's rings?
You describe it as old - but my guess is that it synthetic optical glue which has lost its contact on one or more glass surfaces. Thin oil was used as laminating material in very early - pre-photographic achromats - but I doubt you will be able to get the oil in without forming air bubbles of some size.

Carsten Wolff
15-Apr-2014, 02:42
Sell it (even to me) and get another one.

Simon Benton
15-Apr-2014, 09:58
The separation shows as an oily rainbow pattern across all of the internal lens glass. I was given 4 Fujinons with this separation problem and was just interested in seeing if there was a way to fix them economically.

Steven Tribe
15-Apr-2014, 12:41
Sounds like a complete shear, so the glass will split into components when dismantled. You can fix with clear thin oil (for perhaps 20 years - oil will not support fungus growth) or use canada balsam (bought as a clear liquid). I know nothing about how these particular lenses are built up!

hoffner
15-Apr-2014, 14:13
You can fix with clear thin oil (for perhaps 20 years - oil will not support fungus growth) or use canada balsam (bought as a clear liquid). I know nothing about how these particular lenses are built up!

Funghi eat hydrocarbons which are present in oils. It is a known fact that fungus in optical instruments can use hydrocarbons, PVC, polyurethanes, certain plastics, certain paints and other material (varnish, lacquers) as fuel.