Nikon 8mm f/2.8 Ai - filter carousel

[longzoom]

Some progress here. Forget about the gel filter idea now. A picture is worth a thousand words:

  Hah! Congs! You made my day!  How you did it and what you gonna put inside?  THX!  LZ

[Kuri]

Longzoom, Thanks for your idea about the 'hydroponic press'. I have a pneumatic press, which would not work exactly the same, but decided to use a lower tech method. A rubber mallet.
After spending a lot of time testing the filter adhesive with various solvents, I found nothing that softened the adhesive, which I was surprised about given the list of solvents I tried:
Toluene, Acetone, Methylene Chloride (DMC), Methanol, Lacquer Thinner, etc....
I would really like to know the exact adhesive used for those filters, if anyone knows.

Teflon sheet, with 7/8" hole (slightly larger than filters).
1/2" socket set socket (this fit inside the filter hole, has a flat large surface contact area, almost fills up the hole, but leaves enough edge room for the PEC padding).
Wooden dowel inserted into front of socket (flat back of socket was facing filter).
PEC pad (double folded for cushion, was placed between flat back of socket and filter glass)
Rubber mallet.

The idea of the rubber mallet is a softened strike with a positive drive. PEC pad protects the glass surface from scratching.
Filter was aligned over Teflon hole, and 'WHAM', filter falls right out.
Not guaranteed to work, or to work without breaking your filters, but none of mine broke, cracked, or chipped at all.
At least two of my filters were not subjected to any solvent tests, and they all came out just as easy.

Setup:

[longzoom]

Well done! It is your choice now, what to insert! Keep us informed, please! LZ

[Bill De Jager]

I have an 8mm f/2.8 non-AI that I used on film cameras years ago.  I can't use it on FX Nikons unless I have it AI-converted which would likely harm its resale value.  (It could be mounted with an adapter on a Canon full-frame digital camera, but I already have a Canon 8-15mm fisheye which is native on that mount and much easier to use.)

Earlier this year, I was considering trying to replace one or more filters on this Nikkor lens (and another), but set that idea aside for the time being after running into mechanical difficulties.  Since then Nikon has come out with their own 8-15mm fisheye with half the weight and far less bulk, so I expect to go that route.  I should have a copy in my hands shortly.  The 8/2.8 is just too heavy and bulky for general use, in contrast to the Canon which I have used while hiking.  The new Nikon should be similar to the Canon in usability.  If the new lens is suitable then I expect I'll sell the others.

I appreciate the filter information in this thread which completes the answers to questions I had raised in a previous thread.

[Kuri]

Thanks Longzoom. :-)
In order to use it on a stock camera and to keep the original L1A - Clear Skylight filter for that, I am left with 4 filter holes.
I would definitely populate one with Schott RG850, that leaves me 3 more.
I could put in a BG38 for visual shots, this way giving myself the option of doing Visual/IR composites in Photoshop.
This leaves me 2 more.
RG715 comes to mind, and maybe RG665 or RG695.
Of course one might want to leave the Red or Orange or Yellow in the revolver for doing stronger false color IR, as well as EIR/Aerochrome post processed shot from a yellow minus blue filter.
Ideal, I suppose, one could build an insert contraption, that would allow a single filter to be slid in/out of the space that the revolver was once housed in. That would make it much more versatile,
but perhaps not as quick and convenient.
If someone never needed to use it on a stock camera, but only on a full spectrum conversion, then the L1A - Clear Skylight filter position could be used for another filter.
Oh!! I almost forgot, I would definitely include a U-360 (or UG1) for IR with blue skies. So this drops the number down.
Hard to decide. 

Anyone contemplating all of this, just take a look at this diagram first.   

[Kuri]

Bill, The diagram makes it look quite complicated, but the filter revolver is removed by unscrewing its pivot screw, which is accessed from the rear of the lens after removing 3 or 4 composite parts.
It is not terribly hard to do, but does require the repair manual if you have never done it.
The rear elements are all removed as one composite part.
The front elements are also removed as one large composite part, only in order to remove 4 screws holding the revolver cover on, which can actually be removed without removing the front if you have a very short screw driver, but is arguably a lot easier if the front is removed, but that is very easy to do, one set screw and then the whole front section screws off.
I put everything in small covered containers, zip lock bags, and plastic film cans (for the screws).

One more important thing to point out about diving into this:
When you take the revolver pivot screw out, there is a ball bearing under the revolver plate, and also 2 small plastic washers stacked under the pivot screw,
these are small, and will be lost if you are not being aware of them. They need to be replaced and aligned in place when reassembling the revolver plate.
One needs to pay attention to those two parts, or they will be lost or not resembled correctly.

Yes, I have seen the new 8-15mm Nikon Fisheye-Zoom.
I don't know yet if it has any hot spot in IR or not. Does anyone know?

[Bill De Jager]

Thanks for the information, Kuri.  That's quite a project you're undertaking.

In my case, infrared use of the fisheye is not as important as overall usability. The new fisheye is just another lens when placed in the camera bag, while the 8mm is a monster to carry around and to mount, limiting its practical range of uses.

I actually have a number of fisheyes in several formats, some of which are circular fisheyes, though I haven't tested the circular fisheyes in infrared yet.  I also pretty much stick with ~850 or ~1000nm infrared cutoffs rather than all the other variations you've mentioned, so it works well to just mount the lens I'm using on a modified camera that can also be used with other lenses in the same spectral band.  We're pursuing somewhat different combinations of spectral ranges, so it makes sense for us to pursue somewhat different equipment choices.

BTW, the Panasonic 8mm full-frame fisheye for Micro Four Thirds does well in ~850nm+ infrared.

[Kuri]

Thank you Bill. :-)

Longzoom, What adhesive did you use when reinstalling filters in your 8mm revolver plate?

[Erik Lund]

Very nice work guys! Looking forward to the results


Comforting the rear cell came out in one piece

[Kuri]

Thanks again Erik for your input about all this. Very much appreciated.

Also thanks to Bob Friedman, who has demonstrated so superbly the ability of this lens to do IR. I would not own this lens if not for his artistic examples.

Thank you Longzoom for your hydroponic press idea.  Let me know what adhesive you used for remounting these filters.



 

[Erik Lund]

I would suggest to use one of the glues that stay somewhat flexible, like the ones for mixed materials, for rubber soles on shoes, since you might want to take it apart again,,,

[longzoom]

Thank you Bill. :-)

Longzoom, What adhesive did you use when reinstalling filters in your 8mm revolver plate?

  First off all, I covered the sides of the filters with deep black matte paint - successfully, to prevent possible reflections. Fortunately, filters came back to its cleaned saddles ease, without any efforts. Sorry, I do not remember what was the name of the composite glue I used, it contains of 2 parts, I should mix it together in some certain proportions, wait about 12-15 min before usage. It was completely unnecessary to put it thru the diameter, 3-4 points of that glue was enough to keep the filter deadly cemented to its place where it belongs. BTW, good idea to make the insert contraption! Good luck!  LZ

[longzoom]

I would suggest to use one of the glues that stay somewhat flexible, like the ones for mixed materials, for rubber soles on shoes, since you might want to take it apart again,,,

   Nice idea, really, for future use!  LZ

[Akira]

How about the UV-cure adhesive (actually kind of plastic) like this (Bondic)?

https://notaglue.com/

[Erik Lund]

As long as it is not too easy flowing, fluid,,,