Nikon 8mm f/2.8 Ai - filter carousel

[Akira]

Akira, I would try cerium oxide on both, worth a try, if the surface of the glass is not etched/eroded, then the cerium should remove the problem, but it is hard to know until you try it.

Cerium oxide is available on eBay, etc., in powder form, just mix with water like mud. Also available already mixed in bottles.
Get the good stuff, not from China, often they mix zinc with cerium to make it less expensive.
Either pink or white will work the same.

I've had celium oxide (pink powder) to remove the yellow coating from the flash xenon tube.  The GB was so deteriorated that I could scratch the sticky thingie off using my fingernail!  Oh, well.

[Kuri]

Akira, don't be afraid to try cerium on your 'sticky' filter. :-) It can't make it worse.

Bob, here is what I made:
BG38
RG665
RG715
RG850
U-360
But so far I have no decided how/what exactly to glue them with.
I am still not an expert at dismantling and reassembling that lens. So that is actually the tricky part for me still.
It remains to be seen just how well these filters will work still, infinity focus, etc..
I have you in mind, my interest in this lens originated with your fine IR photos using that lens. You have helped me learn how to use it and process the photos.
From that list of filters, I think I know how you would populate the carousel, all of them except the BG38 which you would probably forgo for the original L1A clear filter instead.
I would not expect you would be interested in the yellow filter.
So:
L1A
RG665
RG715
RG850
U-360

So here are my current ideas on gluing. Let me know any thoughts, ideas, anyone.
Since the glass circles fit so tightly into the carousel holes, instead of gluing the glass onto the metal footing below the glass,
as the original filters we glued, I am instead thinking of only putting some kind of glue around the top, in the crack between the glass and the metal.
This could just be a few drops to hold it in place, or full circumference to also block off any possible light leak that might make it's way through the footing and around the edge of the glass.
Preferably the glue should be non out-gassing, and something that could be removed somewhat easily if the filters needed to be change.
It would be best if the glue is black or non light transmitting.
Something like black silicon, very finely applied around/into the circle crack, comes to mind, perhaps, but I don't know the specifications of that type of glue.
I am sure there is some kind of glue that might work well for all these criteria. Any ideas...let me know.
Am I thinking correctly here?

[pluton]

In theory, the light-fastness of the edges of the filters in their holes could be tested before returning the wheel back into the lens.
Obviously, the less glue used, the easier an eventual filter removal would be. Two or three spots in the circumference might suffice.
I would look to a very thick paint-like material, like fingernail polish. It dries completely and without subsequent outgassing, is easily dissolved later by common solvents.
I'd stay away from RTV "silicone rubber', as there is no known 'safe to use' material that dissolves or removes it.

[Kuri]

Pluton, Thanks for your ideas and advice.
I was thinking of the silicon because it can usually be removed fairly easily without any solvents.

[pluton]

Pluton, Thanks for your ideas and advice.
I was thinking of the silicon because it can usually be removed fairly easily without any solvents.

Yes, IF you can physically peel/scrape it off of the work, then you are correct.  If it happens to attach with good adhesion to a clean surface, it can be a lot of work to scrape off.

[bobfriedman]

Bob, here is what I made:
So:
L1A
RG665
RG715
RG850
U-360

- why not U-330 or a 1mm thick UG-1  instead of the U-360

[Dr Klaus Schmitt]

- why not U-330 or a 1mm thick UG-1  instead of the U-360

Here: http://www.ultravioletphotography.com/content/index.php/topic/2459-the-shape-of-things-to-come/, much nicer blue sky for dual band IR

[bobfriedman]

Here: http://www.ultravioletphotography.com/content/index.php/topic/2459-the-shape-of-things-to-come/, much nicer blue sky for dual band IR

the U-330 looks like it would be better based on the spectrum, greater sensitivity, etc.... and i have used UG-1 extensively.

[Dr Klaus Schmitt]

Guess it is less the graphs, but the visible outcome which triggered the decision...

[bobfriedman]

Guess it is less the graphs, but the visible outcome which triggered the decision...

i guess the U-330 is a UG-5