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Night Vision Help me understand my clip-on optical axis...

Conqueror

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Minuteman
Feb 28, 2008
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North Central FL
I've had thermal devices for some time but I recently got my first clip-on, a TigIR 6z+. I am loving it so far but I am puzzled by an optical issue that I am having trouble understanding. Props to Horta for answering some earlier questions by DM but I figured I should stop pestering him and consult the hive. Here's what I am seeing:

Setup #1:

lN8Zi63.jpg


This is the Tig on its 38mm mount and paired with a Trijicon 1-8 in an ADM Recon-S 1.55" mount. These should be pretty well-matched, right? Well, when I look through the scope, the view is clearly and significantly shifted toward the bottom of the Tig screen by about 20%. I took a photo on 3x power to try to show this. You can see how the top of the screen is cut off by the circle of the day scope much more than the bottom is:

5g1yLz2.jpg


I recognize it's not the best photo, but hopefully you'll take my word for it.

Setup #2:

p5JtZdv.jpg


Same rifle and day scope, but the Tig is now on the 36mm mount. Obviously there is now a much more noticeable offset between the optic heights. And yet, here is the view through the scope at the same magnification setting:

pSAV2Jr.jpg


The screen is noticeably more centered in the day scope and the top margin of the screen is much less cut-off by the Trijicon.

Setup 3:

uR4lUhh.jpg


This is a different rifle but one that also runs the same Trijicon 1-8 scope, but in a much lower set of APA rings. The Tig is still on its 38mm mount and obviously there is now a huge offset between the optics. And yet...

gY4SZVI.jpg


...it gives the best-centered view of all, with the Tig screen roughly centered in the scope and symmetric amounts of margin cut-off at the top and bottom. I have to turn up the screen brightness in this setup, which makes sense since half the light from the Tig is missing the day optic. But it's still the best view by a significant margin.

How can this be? I was under the impression that you generally want to match your optic height to your clip-on height, and yet the most precisely matched setup here gives the worst view. It's super-annoying in Setup #1; above ~4x I feel like I am losing a significant amount of the top of the screen that I don't lose on Setup #3 despite its huge offset. I understand from my discussion with Horta that all three setups should be GTG for shooting as long as I can collimate them appropriately, but I don't want to lose a bunch of my overwatch/surveillance capability to screen cut-off. Any help or lessons welcome.
 
Good question, these are all 0 moa mounts, and both rifles are zeroed at 100 yards. I should have mentioned that. The Cadex rifle has a 20moa top rail but both the day optic and Tig are on the same rail there.
 
Not yet, but I have to say I do not understand how that would change this. When you collimate the Tig it moves the image around on the screen but it doesn't physically move the screen inside the housing so I could try collimating it on each rifle to remove POI shift but that is all digital and this seems like a physical issue.
 
I would try centering the scope elevation and windage adjustments in the middle of the adjustment range. See if that changes things.
 
I ran one of them through its adjustment range, it does not change the view, only the reticle location on the view. Also the whole point of a clip-on is you shouldn't have to mess with your elevation/windage with it, right?
 
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Have you tried moving it away from or closer to the scope objective? Not sure if that makes much any difference or not
 
I have read wig’s thread like 5x. His comments are mostly about collimation, not centering the screen in the day optic. I can confirm now that collimation has nothing to do with the “centeredness” of the screen - I ran through the entire collimation range on the optic and it does not alter this issue, as expected. Distance to objective does not seem to matter, at least not within a couple rail slots.
 
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It does this because the optic isn't centered between the turrets. Every gun shoots different- so we point the center of the optics package at the place the gun shoots to, not the other way around.

It results in this unevenness being present in many clip ons.
 
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It does this because the optic isn't centered between the turrets. Every gun shoots different- so we point the center of the optics package at the place the gun shoots to, not the other way around.

It results in this unevenness being present in many clip ons.
You’re the second person to have said this but I ran one of the optics through its entire elevation range and it didn’t change at all…
 
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What are you torqueing the ADM mount to? It seems that mount is used when offsets are present, do you have a different taller mount to try with the same scope?
 
That scope has been on that rifle for like 3 years so I can’t tell you what it was torqued to but I use a FAT wrench and adhere to factory recommendations. I’ve tried it with shorter mounts on the Tig, that seems like it would accomplish the same thing without having to lose my zero.
 
I've had thermal devices for some time but I recently got my first clip-on, a TigIR 6z+. I am loving it so far but I am puzzled by an optical issue that I am having trouble understanding. Props to Horta for answering some earlier questions by DM but I figured I should stop pestering him and consult the hive. Here's what I am seeing:

Setup #1:

lN8Zi63.jpg


This is the Tig on its 38mm mount and paired with a Trijicon 1-8 in an ADM Recon-S 1.55" mount. These should be pretty well-matched, right? Well, when I look through the scope, the view is clearly and significantly shifted toward the bottom of the Tig screen by about 20%. I took a photo on 3x power to try to show this. You can see how the top of the screen is cut off by the circle of the day scope much more than the bottom is:

5g1yLz2.jpg


I recognize it's not the best photo, but hopefully you'll take my word for it.

Setup #2:

p5JtZdv.jpg


Same rifle and day scope, but the Tig is now on the 36mm mount. Obviously there is now a much more noticeable offset between the optic heights. And yet, here is the view through the scope at the same magnification setting:

pSAV2Jr.jpg


The screen is noticeably more centered in the day scope and the top margin of the screen is much less cut-off by the Trijicon.

Setup 3:

uR4lUhh.jpg


This is a different rifle but one that also runs the same Trijicon 1-8 scope, but in a much lower set of APA rings. The Tig is still on its 38mm mount and obviously there is now a huge offset between the optics. And yet...

gY4SZVI.jpg


...it gives the best-centered view of all, with the Tig screen roughly centered in the scope and symmetric amounts of margin cut-off at the top and bottom. I have to turn up the screen brightness in this setup, which makes sense since half the light from the Tig is missing the day optic. But it's still the best view by a significant margin.

How can this be? I was under the impression that you generally want to match your optic height to your clip-on height, and yet the most precisely matched setup here gives the worst view. It's super-annoying in Setup #1; above ~4x I feel like I am losing a significant amount of the top of the screen that I don't lose on Setup #3 despite its huge offset. I understand from my discussion with Horta that all three setups should be GTG for shooting as long as I can collimate them appropriately, but I don't want to lose a bunch of my overwatch/surveillance capability to screen cut-off. Any help or lessons welcome.
This is unfortunately the nature of the beast with clip on thermals. I had one of the new burris btc 50 clip ons for a while and the mount it came with was horrible. It had the same problem you are experiencing but mine was shifted to the left where nearly a third of the screen was cut off and it was like this with every optic I tried no matter how much i played with the adjustments.

I asked a guy at trijicon about this problem since the people at burris were less than helpful and he just recommended going back to stand alone thermals. So, if its really going to bug the crap out of you, thats your answer, but if you can get over it, screen adjustments should rectify any poi shift. not sure what happened to my text to make it slanted there at the end, def didnt do that on purpose.
 
The Pulsar Krypton has a pretty cool feature when using the objective bell mounts where you leave it loose then cant it around until it’s properly centered up. Then people worry about the weight hanging on the objective, but I haven’t seen any info on how much it would shift things.

Check 5min in on here -
 
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@HKslave I understand it is part of the game with thermal. I guess I was trying to gain a better theoretical understanding of why the best-aligned scope/Tig combo would yield the worst-looking through-the-scope image. If I had a better understanding of the optical cause for this, I could better adjust each setup to minimize it. It is certainly liveable and I much prefer clip-on to dedicated for a variety of reasons, so I don't really see myself going back to dedicated thermals.
 
Have you visually confirmed you’re cutting off Tig FOV? Not sure that’s the same as your day optic reticle moving around on the screen.
 
Have you visually confirmed you’re cutting off Tig FOV? Not sure that’s the same as your day optic reticle moving around on the screen.
You have it backwards. It's not changing the Tig's FOV, that would happen in front of the Tig's objective lens. It's cutting off the amount of the Tig's rear screen you can see through the day optic. That doesn't really require any confirmation beyond looking through the day optic and easily seeing that you can't see the top/side edges of the screen on one setup vs the other.
 
Try adjusting the elevation on the scope. Some scopes move the reticle in the FOV, other scopes move the entire image to give you a zero setting.
 
@HKslave I understand it is part of the game with thermal. I guess I was trying to gain a better theoretical understanding of why the best-aligned scope/Tig combo would yield the worst-looking through-the-scope image. If I had a better understanding of the optical cause for this, I could better adjust each setup to minimize it. It is certainly liveable and I much prefer clip-on to dedicated for a variety of reasons, so I don't really see myself going back to dedicated thermals.
The problem you are experiencing is caused by the nature of a day optics vertical axis. They FOV that is being magnified comes through a very small point in the front of the scope. Its basically the same reason that if you have an IR laser on the front of your rifle you can see it on 1x but if you zoom in the scope will focus right through it so you cant see it anymore. Thats the best way I can think to explain it.
 
You have it backwards. It's not changing the Tig's FOV, that would happen in front of the Tig's objective lens. It's cutting off the amount of the Tig's rear screen you can see through the day optic. That doesn't really require any confirmation beyond looking through the day optic and easily seeing that you can't see the top/side edges of the screen on one setup vs the other.
By Tig FOV, I’m referring to the screen’s view.

Just trying to fully understand what you’re looking at, and proposing.

You mention it’s cutting off part of Tig’s screen, but every pic shows the same square view, including the top, with the top corners rounded. If the day optic view was cutting off the top of the Tig’s camera, it would be rounded at the top. And the screen shows BBH 0.8x at the top (and seemingly in the same position) in each pic. Wouldn’t that disappear if you were missing some of Tig’s screen?

If you’re going purely from the reticle’s apparent shift in the screen, suggest you at least confirm, by viewing an actual object through the Tig, and swapping scopes (without moving the rifle), to see what’s actually going on.
 
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This is probably a dumb question, but check the obvious first, right?:

Is the Tig zeroed/collimated yet? I noticed this with my Tig on some of my rifles, but they all had slightly different scope heights so I just lived with it.
 
As noted above this is completely independent of the collimation, which moves the image around on the Tig's screen but does not physically move the Tig's screen around in the day optic.