Looking For Nikon S-series Trinocular or Binocular head piece.

[stitchy.mitch]

I am looking for a trinocular headpiece for my Nikon S-kt. It was a high risk purchase on a used item and it turned out one of the prisms in the headpiece has a crack which is bending the lightpath to the right eye. It is causing two images to be produced, and it appears whatever causes the crack has also affected the trinocular eyepiece, so its view is offset vertically significantly.

https://scontent.fyvr3-1.fna.fbcdn.net/ ... e=5D385A90

and

https://scontent.fyvr3-1.fna.fbcdn.net/ ... e=5D316AEB

I am an amateur and I am hoping it could be the case an experienced technician thinks it is something else and that a crack like that in that place could not produce the issues I'm describing.

If anyone has anything like this for sale I would buy it for a reasonable sum.

~Mitchell

[abednego1995]

Hi, that's a nasty crack in there...
Having double images indicates a mismatch in the optical axis somewhere in the train. In the Nikon S series Jentsch type binocular, this often happens with the displacement of the center columnar prism in your second photo.
When you disassemble this head, touching the 3 screws that hold that prism to the faceplate is a big no-no. Removing multiple prisms from the frame will exponentially make realignment difficult.

*the below instructions are under the assumption that you have the 45-degree prisms right under the ocular tubes in their proper places. Look for fine alignment marks on the frame they make at assembly*

Reassemble the head sans the cover which protects the center pivoting slot lever, and the lever itself which keeps the oculars at an equal distance.
This will make both ocular tubes free, and possible to access the 3 screws that fix the center columnar prism. Loosen the screws only so much as to allow slight movement to the prism by tapping those screws sideways with a fine screwdriver.
Mount a 40x objective on the scope and find a fine point detail on a slide. Peering through either ocular at one time will give you a sense of the displacement.
Tap those screws horizontally and vertically until you have reasonable field match. Tighten the screws very gently and finally firmly. Reassemble.

This is a highly frustrating job, but it is possible.
Regarding the crack, I suspect it will be within the field of view. If not, it will at least be a point for stray reflections causing a drop in contrast.

If nothing goes well, I can provide either the trinocular (U) or binocular (B) head at a reasonable offer (Given that shipping might be prohibitive from Japan.)
PM me if you're interested.

Cheers,
John

[Scarodactyl]

I have a vague recollection that these older s series scopes have the same head dovetail as the labophot series? If they are compatible getting a good trinocular head on eBay should not be too hard, as reasonable deals seem to come up fairly frequently.

[stitchy.mitch]

Thank you John, for the instructions on solving the problem. I attempted the repair and while it took me quite a while and some patience I was successful. However it is hard to gauge if I am getting the most out of my scope and if the crack, or small errors in alignment are putting my images off; and causing strain to my eyes.

So far the images is one again and appears very clear. I will PM you likely to inquire about the trinocular head soon. Many thanks.

~Mitchell