G3 PVS 14.

The numbered diopter adjuster, and the indicator ring seem to be out of alignment in relation to each other.

The diopter moves the lens in/out just fine, but the white dot on the indicator plate looks to be in about the 9-10-o-clock position when viewed from behind/mounted on a j-arm.  The central point in the range of motion on the numbered diopter ring looks like it should be almost 180-degrees different, around 3-4-o-clock.

Is there a way to adjust, or remove/reinstall these to match up with each other without compromising the units seal, or needing a nitrogen purge?

Not something I can’t live with (can’t see numbers in the dark, anyway). But if it’s an easy fix...

TY. I’m going to do my best to ignore/forget about it. The adjustment works when necessary, so I think the best solution is to leave well enough alone. So happy with my first monocular.

Why even put indications on there then if they are always wrong?

You can move the indicator plate but you need to disassemble the eyepiece somewhat. If the diopter adjustment stops just before +2 then the plate is roughly at the right location, but if not, then if you absolutely want to you can move it.

Even if it does not stop close to +2, but is in any useful range, for example you can adjust the numbers from +1 (or even just slightly positive) to -2, then that should be enough for normal use and you can just screw in or out the whole eyepiece to reset the zero diopter.

If you want it to be as precisely aligned as possible then you will need a magnifying diopter scope to peek into the eyepiece while doing the adjustment, but two other easy methods are:
- loosen the locking ring by turning it clockwise (looking from behind the unit). Grab it gently with your thumb & index finger making as even pressure as possible and turn.
- now you can grab the eyepiece in the same manner. Grab the larger outer part of it, that which was touching the locking ring
- set diopter mark to zero and see to which direction you needed to go to zero, were you at the plus or minus side
- if the setting you run normally with was on the plus side, you need to turn the eyepiece counter clockwise to bring it further from the tube. If it was on the negative side, you need to turn the eyepiece clockwise to screw it toward the tube
- so basically you are adjusting diopter by turning the whole eyepiece (moving the lens cell in / out, just as adjusting diopter normally does)
- now as the indicator is showing zero, either:
1. look at the image with your eye while you turn the whole eyepiece and stop when the image becomes sharp
2. grab a camera, focus it to the stars (either manually, or after autofocus disable it so the focus remains the same. Or if it shows you the focus range in meters anything >70m is good), and then turn the eyepiece while looking at the eyepiece through the camera to see when it is the sharpest (gets you closer to real zero than with your eye, even with corrective glasses if you need such)
- retighten the lock ring

If the diopter indicator plate is all wonky, or the adjustment range is not sufficient, then you need to do further disassembly. The whole procedure is best understood by reading the technical manual that you can find searching google for "7451865 PVS-14 TM-11-5855-306-23-P" (one of the first results)

This applies to a mono only. In a bino if you don't have access to collimation equipment and want to retain collimation, you need to mark up the angle of the whole eyepiece assy after you adjust anything so that you can place it at the same position it was. If you need to take the lens cell out, then marking the angle of the lens cell is important as that is the part is offset to enable collimation adjustments.

I don't think almost anyone cares what the indicator plate is showing. You will be fiddling with it anyway. Especially with a bino, storing it can touch the diopter focus ring and throw either side off by a little and a mismatch between sides will show when next used. In a mono such small changes don't matter nor are visible. But even then the indicator plates are so coarse that they are almost useless anyway.

Edit: I just reread your post, and somehow the clock positions you wrote flew past me. Seems it is enough far off that you indeed would need to either move the indicator plate, or take out the whole eyepiece from the PVS-14 body and put the lens cell on another set of threads. The indicator plate can be moved by taking of the snap ring on top of the diopter focus ring, rotating the focus ring so that it lifts up just a bit, and then move the indicator plate to a place where you wish. Turn focus back and reinstall snap ring. You won't loose the seal doing this nor if you are resetting the zero (which you will need to do anyway if it is off). You may break the seal if you turn the eyepiece out too much and the O-ring pops out. There is quite a bit of threading on the housing, but it is possible to pop it off depending on where it is set now. Probably it is screwed pretty much all the way in though.

Mine seems to be almost 180 degrees off, and yeah all that to get it 'fixed' isn't worth it.  Maybe one day when I'm feeling super industrious I'll black out the scale and then make my own markings.

The bigger problem I'm having though, is that I run out of adjustment for actually focusing using the diopter.  This is while wearing contacts with an up-to-date perscription.  As I turn fully counter-clockwise (looking through the eyepiece), the clarity is still getting better as I max out the adjustment.  It's not all that far off, but enough that still leaves stars fuzzy no matter where the objective focus is set (goes from getting better back to getting worse without ever coming into perfect focus).  I feel like I must be doing something wrong trying to focus these things.

Last related FNG question, there's some sort of ring just behind (toward the eye) the diopter focus ring that sits flush with it.  They free spin and never tighten unless the adjustment is fully clockwise.  Is that normal?

That ring you speak of is the snap ring and all it does is keep the focus ring from coming out / keeps it in place so that instead of it screwing out it forces the lens cell to move instead. The cell has threads and so has the focus ring, so either has to move, and in this case it's the lens cell because of the snap ring. When fully clockwise the lens cell wont move further in so the focus ring tries to push itself against the snap ring.

Your focus problem is solved by loosening the lock ring (that ring which is closest to the main housing) and then screw the eyepiece more outward. Then tighten the lock ring back. The only thing to know is to grab the ring and also the eyepiece as evenly as possible. Especially the lock ring as it flexes quite a bit and can be hard to get turning in the first place if you apply pressure on one point too much. So first lock ring clockwise to separate it from the eyepiece, then eyepiece counter clockwise, and finally lock ring back counter clockwise. Moving the whole thing out, further from the tube, is the same as adjusting diopter towards positive figures, "making the image appear further", so you will gain more room for adjustment that way.

Edit: a gazillion edits, hopefully you didn't have an email notification and click it right away as I probably had something wrong. Easy to get mixed up in in/out clockwise or not, etc.

Only thing to add is that if you unscrew the oculars like instructed and you have binos, you will lose collimation. The trick there is to mark the location of each ocular relative to the housing (just a simple scribe mark) and make sure both get unscrewed in increments of 180 degress. Or is it 360 degrees? Someone will correct me. Was this an eBay special or something? No excuse in running out of diopter adjustment range in that direction if someone half-competent put these together. Have you always had this issue? I ask since on a PVS-14 or MOD-3 housing, even with the ocular screwed down all the way onto the threads on the housing, there's still some room past zero diopter in the positive direction. Only time I ran into this issue is when I'm trying out tubes in a rush and don't secure the tube inside the housing with the lock ring. Tube can then slide back a bit and then you lose the ability to hit zero diopter.

It's a MOD3-B from TNVC.

Wonder if there is multiple revisions of Mod3 that differ in the amount of threading or in something else. Or if different flavors of eyepieces have slightly different limits to lens cell travel relative to the housing. Or even maybe slimmer lock rings that would allow screwing the eyepiece a bit closer. If there exist different spec parts then no doubt someone who's done a million PVS-14 could still just slap the eyepiece on all the way in and be done with it, not realizing that some part is different from previous builds and allows the eyepiece to screw in a bit more.

There was a guy recently with a PVS-14 from TNVC with the eyepiece screwed in all the way (or almost at least) and thus the lens cell protruding back quite much. Still had enough travel for zero though, but I think he just screwed the eyepiece out a bit anyway.

It was protruding like this so he too was at the edge of the adjustment range:


I don't own a PVS-14 nor don't have access to the amount of different housings & eyepieces some of you do, so can't tell if txdx is right in that it should still have enough adjustment range to go to zero. You could verify that with a camera, but I doubt it is necessary. If he is right, then my knowledge stops here and you should ask TNVC if they would look at it. Not good if the tube is loose. I am guessing it is something else, but it is just a guess based on nothing but a tickle in my butt.

And yeah, if adjusting this in a bino, then like txdx said you need to screw in/out in full 360deg turns in order to retain collimation. Easiest to mark the position of the indicator dot relative to the main housing and making sure they align after the adjustment. Then all is fine and same as it was collimation wise.

Possible there are some combinations of eyepieces and housings that have the tolerances stack up such that there's insufficient adjustment range. I haven't run into it with a combo of Carson and ITT housings and Carson, ITT, Edmund, and Qioptiq eyepieces. Wasn't a methodical study that checked every single possible permutation but I've done it often enough that I probably would have found a bad combo by now. My uncorrected eyesight is pretty bad so I usually screw down the eyepiece all the way to get it to focus past -6 diopter. Even with the backing ring removed, I don't think I ran out of adjustment range and could hit 0 diopter. The only variable that caught my attention is that the distance between the output coupler of a tube and the housing of the tube itself varies from tube to tube. Could achieve focus past -6 diopter with some tubes but not others. The distance delta is small enough that it becomes apparent when the lens cell is screwed in all the way and probably would not be an issue elsewhere in the travel.

Haven't run into it with MOD-3Cs but I only had one MOD-3B that I tried different eyepieces on. As much as I love the products from AB Night Vision, it is somewhat of a small scale operation and Adam seems to iterate his designs fairly often, meaning my MOD-3B housing may be dimensionally slightly different than another one made earlier or later. Still doubt it'd be that far out tho.

Only time I ran out of adjustment range was on an ANVIS housing with the old ANVIS eyepieces. Screwed them down all the way like I normally do and then realized I had to back them way off.

Fixed my issue based in the descriptions provided here, THANKS!

Easy as could be: adjust the eyepiece focusing ring all the way out, then in just a hair to reduce tension on the snap ring.  Popped the snap ring out with my fingernail. Spun the focusing ring out a little more to loosen up the indicator plate (not enough to come off the threads though, and just enough to get the ring  off the little anti-rotation stud).  Moved the indicator ring so that the dot was in it’s proper position, centered in the numbered dial’s range of adjustment.  Screwed the eyepiece focusing ring back down, and reinstalled the snap ring.

Easy as could be! And now I have a little better understanding on the assembly of that end of my optic!

Cool, great to hear you got it solved!

If I understand you correctly, the point where the indicator plate is centered on the adjustment range is then actually somewhat showing the wrong numbers. Though at least you have any numbers so that's a plus

It should travel about between +2 and -4 (or something like that, more to the negative side anyway). If you set the indicator plate so that at max outward setting the plate shows just about +2 it's pretty close, but now that you are inside the range, you could always recheck the zero, either with your eye or if you have a camera that you can focus manually to infinity or lock the autofocus to stars and come back inside, then with that.

It is actually easier than what you already did, only more steps.

Set the diopter to show zero and during the adjustment keep it there if it moves. Loosen the lock ring (the large diameter ring closest to the housing) by turning it clockwise (looking from behind) so it loosens from the eyepiece. Then grab hold of the eyepiece from the largest diameter part, and start turning while at the same time looking through the eyepiece (with a relaxed eye / camera). This is exactly the same as adjusting diopter the normal way - you either bring the lens cell toward or from the tube. When the view is clear, retighten the large lock ring and you are set. Eyes tend to focus past infinity, or wherever, so a camera is more reliable. Another is to look through it with another scope, a magnified day scope for example, and when the image is clear, you are close to real zero.