Telescope Reviews: Fuji OEM winged eye-cups for FMT-SX models?

There were (are) molds from WW II still at some rubber companies. Please let me know if you find some sources. One source I used is out of business. I do not know what happened to the cup and facemask molds ( still Government property, but long forgotten) which they had. One of the products from one of those molds was a winged eyecup, which was for some WW II Navy rangefinder, as I recall . I might have some yet,and could probably buy some, but have not been active with it for about a decade. There is a minimum quantity to order from the molders, ( if they still remember the product and the mold). There is such an individual winged eyecup(or was) for the Navy 20 x 120 binoculars.

I made Delrin threaded adapters for those cups and for the 2-hole Navy WW II rangefinder Lone Ranger style facemask mentioned above, sold by me and others in EPDM, natural rubber, and various grades of silicone . But with the several variables of diameters and eye reliefs, and the complication of re- focusing(particularly with stretched tight fits), as well as the usually very small quantities wanted by the customer, it becomes questionable to devote time to machining the fine pitch and short threads adapters required for some setups of the rubber cups and facemasks. Small , short setscrews (grubscrews in UK), help for a threadless solution, when applicable.

I did make some adapters for the F series. It is possible to discard the aluminum pushrings, and make all-Delrin pushring-eyecup or pushring-faceshield adapters. There is only a very short male thread available to mate, in the F series. The Navy facemask requires stretching to fit the F and the 25 x 150, and nose relief can be a problem. The original equipment winged rubber eyecups for the Fuji Meibo/Fujinon 25 x 150 trunnion model, and the Nikon 20 x 120 I and II, were hard, and had nose-relief problems, so were little used. I made an adapter semi-production run for the Nikon 20 x 120 I and II. Those give better effective eye and nose relief, and eliminated some serious brass-aluminum-saltwater galvanic corrosion on the Nikons,and on the very early, 1970's Fuji 25 x 150 brass to aluminum eyepiece mechanism. I made some for the Fuji Meibo 15 x 80, and a number for the WW II B&L 7 x 50, various models , as well as the SARD 6 x 42 and the mounted WWII Busch design 45 deg.inclined 10 x 80. There is enough variation the the thread size Schneider vs. Leitz vs. Busch vs etc, to preclude a one-size-fits-all production run. The cups and facemasks , though loose, can often be used on handhelds, without putting grooves in the pushrings.

I made a mold to copy the headrest on the WW II Carl Zeiss 25 x 100. I still have that mold. The foam I used was semi-banned by EPA or OSHA, after the Bhopal incident, or some other snafu. There are, no doubt, replacements, but I have not done any of this sort of production for years.

A more recent solution, which I posted a few months ago,with pictures, is making knife or scissor cut cups and forehead cushions from the foamed tubular rubber pipe insulation, similar to diver wetsuit material, or the lighter PE foam, sold at Home Depot, Lowe's, etc . These are quite comfortable. In the dark, who cares about their appearance? The material is inexpensive, and with a few minutes of trial and error, one can get the appropriate eye distance and wing angle. The cushions are easy: Glue, nylon cord, and wood spacers may help, if needed.

If one were to order some winged Navy WW II eyecups, or WW II facemasks, perhaps 50 each, from a molder, would the astronomy market buy them (solar?), without a lot of onesies and twosies custom machining?

Has anyone an alternate solution or source for the rotary winged eyecups on the B&L Mk. 21 7 x 50? Usually, all that remains of the originals is the cold aluminum rotating ring. Such is the case with one I acquired about a week ago. Its objectives need recementing. That, and the proper recollimation, to say nothing of prism cleaning, when required, takes a big chunk of time. The WW II sealing wax brew, before they switched to rubber seals, requires xylene or toluene(yuk!), together with many Q-Tips, for cleanup in reasonable time. Has anybody tried something else for this purpose? Ultrasonic? Citrus based? The Mk. 21 B&L is tough, lighter than the Mk. 28, and has fine images, at least near the axis. The SARD Mk. 21 may be the same eyecup assembly. I have forgotten, and it would take a few minutes to check this. I do not care for the yellow tint and the setscrew diopter lock, drilled at assembly, on the SARD Mk. 21.