Nikon Monarch ATB Binocular Broken Eye Cup Replacement

August 15th, 2014 § 13

Nikon make a tremendous set of binoculars in the Monarch ATB series.  I was drawn to this model after Cornell Lab reviews that consistently place these binos in the same league as models many times their price.

I work and photograph in some pretty hostile environments – from the Arctic to the Antarctic, to remote parts of the New Zealand wilderness, and deliberately chose the lower priced model thinking I could wreck or lose several binoculars for the price of one Leica, Zeiss or Swaroski.

High Arctic Nanavut, NZ Sub Antarctic Islands, Antarctica - the Nikon Monarch's have had a good life so far

High Arctic Nanavut, NZ Sub Antarctic Islands, Antarctica - the Nikon Monarch's have had a good life so far

But alas, after a few years they’re still going strong after hardy service in salty coastal areas, mountains and near the Poles. But for one weakness, a broken eye cup ring (a common problem I believe because of the very thin plastic design and normal wear and tear) they have been excellent.

The thin plastic ring holding the eyecups eventually fails on Nikon Monarch Binos. A known weakness but easiy fixed though

The thin plastic ring holding the eyecups eventually fails on Nikon Monarch Binos. A known weakness but easiy fixed though

I was initially drawn to Don Enright’s post about replacing the eyecups and would have used his post to make repairs, but have found there are… some important changes to replacement eye cups – hence this new post.

I contacted the Nikon agent in New Zealand about parts.  They had to get special permission from Nikon to be allowed to sell the parts without the repair being done in house. After showing them Don’s post, and convincing them of my competence in mucking with stuff, they set out ordering.  It sounds like they found it hard to get the right part numbers, possibly due to the various models (see below for part numbers).

Fortunately it appears that the eye cups are fairly universal.  The parts arrived (about NZD$50.00 incl GST and shipping) and I immediately found they were significantly different to the originals.  Nikon have obviously tried to improve their design ( but it doesn’t actually look like they’ve strengthened the weakest part).  Oh well, the tiny ball bearings that click lock the rotated eye cup into place have gone – they fell out a long time ago, and are now small rollers;  hopefully these will be better?


Remove the old eye cups by screwing the whole unit (rotating rubber eye cups and base ring) CLOCKWISE (opposite threaded to normal).

Screw the new base ring on ANTI-CLOCKWISE but only a few turns, as you’ll need to rotate yet to get the bits in.


Slip the rotating ring over the base ring (make sure you have it the correct way up) and then angle it so that you can drop a metal roller into the slot (left photo below). Do this 3 times with all the rollers by angling the roating ring to stop the previous rollers from falling out. I suggest you do this over a surface where you will find a roller if it gets away!

nikon_monarch_binoculars_eye_cup_repair_3_wThen install the three small screws through the rotating eye cup and into the base ring.  Once all three are installed then carefully turn the whole unit down (screw ANTI-CLOCKWISE) and tighten it into place.  Becareful not to overtighten as you may crack the base ring again. However, you will need to tighten it enough to stop it unscrewing when you adjust the stiff new eye cups.

Install the rubber eye cups over the unit and you’re done.  I note my old eye cups had glue holding the rubber hood on.  My new ones are tight and I’ll see how I go without glue for a while.  I also wonder about putting some loctitie or similar under the base ring to stop it unscrewing in the field, but have chosen not to at the moment – I’d hate to compromise the intregity of the weak ring below.


I’ve photographed the parts packets I recieved from Nikon in case anyone wants to get part numbers.  Note that I can’t be sure which parts came in which paackets sorry.  But it should give your parts people enough to get started with.

nikon_monarch_binoculars_eye_cup_repair_part-numbers_wWell, hopefully if you’ve been in the same boat as myself (and Don Enright), you don’t chuck out your good bins, a 15 minute repair will see you up and running again.  Good Spotting!

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§ 13 Responses to “Nikon Monarch ATB Binocular Broken Eye Cup Replacement”

  • Rajnish Pradhan says:

    Need a pair of eye caps of nikon monarch 8×42

  • John H Felix says:

    monarch 3 10×42
    On my Elk hunt I noticed the eye cup was sliding little funny when I pealed the rubber on the eye cup back a screw fell. I spent 2 hrs trying to find it. after finding the little screw a notices it was the screw that was in the journal for the eye cup to slide up and down. well later that day while chasing some elk I saw the rubber cups had come off. Is there any way to get some sent to me and how much it is

  • Dat Hoang says:

    I’ve been using a a pair of Monarch 5 8×42 from 3 years ago, they’re still amazing. Hope I won’t have to repair them soon

  • Chris says:

    are you able to tell me who you got the parts through as im struggling to find the agent.


  • Rob says:

    Hi Chris, yes, I ordered via the NZ Agent. They had to confirm first from Nikon if it was a repair that could be done without them doing. Seemed overly cautious, but they were helpful. Regards, Rob

  • Borja says:

    Thank you for this very useful post. You saved my cake!

    Now, a note regarding the small rubber rollers. After several years my eyecups (Monarch 5 8×42) have become very stiff. Curiously it happened to both at once. It might be the rubber drying out, maybe with dust making it worse, and/or high temperatures (Southern Spain is hot in Spring and Summer).

    Anyway I have restored them to fully operational state just lubing the rollers with a bit of vaseline grease. Now they are smoother than they ever were.

    I wonder: did yours become stiff, so much that you forced the threads? I am asking because one of mine became so stiff it unscrewed when I tried to twist them.

  • Rob says:

    Hi Borja
    I’m pleased that was helpful. I’m not sure what broke the rings apart from them being way too thin, but I did notice that the old rollers (which were actually round ball bearings not rollers like the replacements) did get a lot of corrosion from the marine environments I worked in. Would be worth putting something like a lanolin (wool grease) product on them possibly – firstly to limit corrosion, and secondly to lube them. I know CRC make a good lanolin product which should be easy on the plastic. Cheers and all the best, Rob

  • David says:

    Hi there can you please provide the contact details for service people you contacted in NZ as I need to make the same repair. Thanks heaps great article

    Cheers David

  • Robert Camper says:

    I need eyecup for left eye on Monarch 8×42

  • Rob says:

    Hi, looking at my notes, I worked with Aliese Booth at Macalisters in Auckland. It was mid 2014, so you mileage might vary. Regards, Rob

  • Thank you for all this. I am mostly very pleased with my Nikon Monarchs… but this eye-cup problem is sad.

    I was lucky the first time the eye relief cup screws came out: they were caught in the track and I was able to put everything back. But on a trip I lost two of three screws on one side, so I glued the cup in the out position that is my norm for wearing contacts… so now this is not usable with my backup glasses.

    Now home, I look at the other side, and 2 of the 3 screw slots are open at the base so will give way soon: more glue.

    BUT WHY DOESN’T NIKON JUST SELL us replacement eyecups fully assembled & ready to screw on? What is that about?

  • Al Peña says:

    Hi Rob, got the same problem with my Nikon ActionEX 10×50 6.5 waterproof binos left side eye relief. Kindly please let me know how I can get the parts needed to repair my binoculars. The tiny ball bearing is still attached to the body if that’s of any importance. I’ll appreciate any help and thank you in advance. Al

  • Dominic says:

    I ordered eyecups from Nikon, but I received the eyecup, 2 small steel ball and 2 click rubber but I can not figure where I must put the steel ball? They don’t have small screw like mine… Someone knows how to assemble it? Nikon answer me that they are not authorized to share diagram…

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