Inside a Nikon 6x15 Monocular
When I’m visiting somewhere scenic, I often think to myself, “If only I had some binoculars right now!” The trouble is that my binoculars are bulky and aren’t something I enjoy lugging around. Monoculars aim to solve this issue by sacrificing stereo vision for increased portability. After doing some research, I concluded that most inexpensive monoculars are cheap junk (and still bulky too). One option appealed to me though: Nikon used to make a pocketable monocular, and I decided to give it a try.
This monocular model hasn’t been manufactured for years, and quality Nikon optics command a significant price premium over generic options. Thankfully, I found what seemed like a great deal. While Nikon monoculars regularly sell for about $125, I won one in an auction for $45. The catch was that I had to import the monocular from Japan in unknown condition.
When the monocular arrived, I looked through the eyepiece and was disappointed. The view was significantly dimmer than I expected. Taking a closer look at the optics revealed a problem: something (most likely mold) was blocking the light.
Without a warranty or cost-effective professional repair options, I decided to take the monocular apart and see if I could fix it myself. While I don’t have a clean room to perform precision optical repairs, I was fairly confident I couldn’t make things much worse. With a few plastic tools, I was able to carefully pry open the plastic housing of the monocular and look inside.
I suspected the root of the problem was mold growing on the optics (a common issue). Unfortunately, this theory proved to be incorrect.
Inside the monocular, there are two prisms, and each prism has a silver mirror coating applied to reflect light. Unfortunately, the coating on one of the prisms was catastrophically damaged. I suspect the damage was caused by a chemical reaction between the prism coating and degrading adhesive foam inside the monocular.
At this time, I have no way of replacing or repairing a damaged prism —-so that’s end of this monocular story. I plan on keeping the monocular in case it becomes useful for spare parts, or if I ever come across a spare prism. Otherwise, this project was a gamble that has yet to pay off.
There very litte information about these devices online, so I thought it would be worthwhile to post a couple teardown pictures in case they are of use to someone. I think that this monocular is a promising device, and had it not been irreparable, I would have enjoyed using it. It’s extremely compact, easily fitting into my pockets. There is also enough eye-relief for glasses-wearers. From the limited testing I did with a reduced aperture, I didn’t find the microscope-style magnification feature to be useful (the focal plane was much too narrow). Also of note: distance markings are a permanent part of the eyepiece.
Here is a gallery containing the remainder of the teardown photos I captured:
