Post by SteveW on Apr 15, 2024 20:12:42 GMT
Guys,
SWMBO is a bit of a Birder and quite a few years back invested in a decent pair of binoculars, some Nikons. All good until she tried them the other day. No visible damage but the two barrels seem to be looking at two separate places. Her first reaction was "they're broken, I must have dropped them, I need to go buy a new pair". I checked them and sure enough they were a bit broken but buy a new? Hang on, let me look at them first.
A quick search on the web and sure enough there are a number of forum posts and Youtubes on realigning binoculars' internal prisms. After checking a number of sources I was ready to have a go. On the face of it its just a case of locating the two adjustment grubs screws for each barrel, noting their position and giving them a coordinated tweak. However, the actual adjustment is far from straight forward given the internal geometry so loads of scope to cock it up completely. Interestingly a couple of sources recommended using a prominent star, at night, as a reference while aligning and to focus the fixed barrel on the star and defocus the other barrel. Then its just a matter of centring the focused star in the centre of the defocused star.
No visible sign of the promised adjusters, they were hidden under the fully enclosing rubber grips and they weren't giving in without a struggle. Turns out by using a small screwdriver pushing in through where the strap lugs appear I was able to carefully separate the the rubber from the barrels without damaging the edges. Turns out all that was holding it all together were a number of strips of double sided sticky tape.
So far so good. But then it occured to me. If these things got dropped it wasn't that they needed adjusting, they needed being dropped from the other direction. None of the references suggested this.
A bit more fiddling and I'd managed to unscrew the two forward lens assemblies from the main body and was able to look in. Sure enough there were large cracks in the paint securing both prisms. I had hoped that only one prism had moved indicating I only needed to tweak that side. No such luck.
None of the references I found suggested checking for witness cracks in the prisms glue/paint to indicate which barrel needed adjustment.
Interestingly the prisms simply sit on an internal reference surface and each is held there by a transverse leaf spring that sits in two slots in the barrel sides and the adjuster screws just nudge them around before getting a dab of paint to fix them.
In my early attempts I just nudged the prisms to close the cracks in the locking paint and it worked. Certainly the image is now zero'ed and the binoculars are useable, just.
So far so good and time to share here before I continue fiddling and cock it all up.
SWMBO is a bit of a Birder and quite a few years back invested in a decent pair of binoculars, some Nikons. All good until she tried them the other day. No visible damage but the two barrels seem to be looking at two separate places. Her first reaction was "they're broken, I must have dropped them, I need to go buy a new pair". I checked them and sure enough they were a bit broken but buy a new? Hang on, let me look at them first.
A quick search on the web and sure enough there are a number of forum posts and Youtubes on realigning binoculars' internal prisms. After checking a number of sources I was ready to have a go. On the face of it its just a case of locating the two adjustment grubs screws for each barrel, noting their position and giving them a coordinated tweak. However, the actual adjustment is far from straight forward given the internal geometry so loads of scope to cock it up completely. Interestingly a couple of sources recommended using a prominent star, at night, as a reference while aligning and to focus the fixed barrel on the star and defocus the other barrel. Then its just a matter of centring the focused star in the centre of the defocused star.
No visible sign of the promised adjusters, they were hidden under the fully enclosing rubber grips and they weren't giving in without a struggle. Turns out by using a small screwdriver pushing in through where the strap lugs appear I was able to carefully separate the the rubber from the barrels without damaging the edges. Turns out all that was holding it all together were a number of strips of double sided sticky tape.
So far so good. But then it occured to me. If these things got dropped it wasn't that they needed adjusting, they needed being dropped from the other direction. None of the references suggested this.
A bit more fiddling and I'd managed to unscrew the two forward lens assemblies from the main body and was able to look in. Sure enough there were large cracks in the paint securing both prisms. I had hoped that only one prism had moved indicating I only needed to tweak that side. No such luck.
None of the references I found suggested checking for witness cracks in the prisms glue/paint to indicate which barrel needed adjustment.
Interestingly the prisms simply sit on an internal reference surface and each is held there by a transverse leaf spring that sits in two slots in the barrel sides and the adjuster screws just nudge them around before getting a dab of paint to fix them.
In my early attempts I just nudged the prisms to close the cracks in the locking paint and it worked. Certainly the image is now zero'ed and the binoculars are useable, just.
So far so good and time to share here before I continue fiddling and cock it all up.