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Posted: 4/14/2016 4:34:08 PM EDT
This topic is a dupe, but the thread is not. There is content in the old thread that prevents me from wanting to associate my video with that thread. I think my video adds value to this discussion.

Here is the video:
YouTube: Aimpoint Thermal Drift? Potentially Not Just an EOTech Problem
Additionally, to prevent the content of the video from being taken out of context I have decided not to post the results seperately.

Guide for Below:
A.) Represents the maximum deviation over the course of the hot and cold tests.
B.) Represents deviation from initial ambient temp zero to post-testing ambient zero.

Trijicon Statement (-60*-160*F):
A.) 1.9 MOA
B.) 1.1 MOA

EOTech Statement (-40*-122*F):
A.) 5 MOA
B.) 2 MOA

Aimpoint Statement:
"Aimpoint sights do not suffer from 'Thermal Drift'."

Key Discussion Points (Not that this is a guided discussion by any means):
Do you think Aimpoints have some degree of thermal drift?
Do you think all scopes, regardless of type, have some degree of thermal shift?
What are the likely contributing factors that cause thermal drift?
Why [and at what point] is Thermal Shift significant?

Link Posted: 4/14/2016 5:06:47 PM EDT
[Last Edit: 4/14/2016 5:46:37 PM EDT by shootertim]
I am by no means an expert, but the one variable mentioned at the end of the test, about the mount makes sense. At such extreme temps, the mount is going to expand, or contract, the same goes for the tube itself. Those factors combined seem like they could cause a shift in impact. Taking all of the variables into account, the Aimpoint still seems acceptable to me. In your video, at what distance were you from the target, you may have mentioned the distance, I just didn't catch it? I think that all optics are gonna experience some sort of drift, under those conditions.
Link Posted: 4/14/2016 7:56:46 PM EDT
Originally Posted By njb242:

Do you think Aimpoints have some degree of thermal drift? Yes
Do you think all scopes, regardless of type, have some degree of thermal shift? Yes
What are the likely contributing factors that cause thermal drift? ....?.... Stuff expands and contracts?
Why [and at what point] is Thermal Shift significant? When it is enough to cause a miss at the "effective" range of the optic.

View Quote


Testing needs to be testing with just the Aimpoint itself. There are too many variables in your testing setup to form anything close to a valid conclusion.
Link Posted: 4/14/2016 8:53:15 PM EDT
Thank you.
Link Posted: 4/15/2016 12:39:17 PM EDT
25 yards. Yes, not definitive by any means, but I do think the linear trend is noteworthy and that an optic has a lot more moving parts than a mount.

How do you think manufacturers conduct such tests?
Link Posted: 4/17/2016 8:00:33 PM EDT
Because there was a lot more interest first time around
Link Posted: 4/17/2016 8:39:27 PM EDT
Would you be willing to do a similar test w/ a conventional optic?

Another route might be to video the dot drift as you take the optic from the oven, and then add your dry ice. Cut a hole in the side of a cooler, and just time lapse video against a target.
Link Posted: 4/17/2016 10:17:46 PM EDT
I believe that optics and the weapons themselves experience a POI shift from temp. extremes.

But, what is the actual affect on the end user. I'm trying to think of a scenario where this shift would affect me. I live here in N. Florida and I shoot year round with the high summer temps close to 100. In the winter, if I can make it out early in the morning, on a very cold freak, once in a century winter freeze, say 20 degrees, I may experience a 1-2MOA shift from my summer zero?

I experience more shift depending on if I had coffee or tea that day.

Still a good video. Keep up the great work.

Link Posted: 4/18/2016 4:36:10 PM EDT
Maybe I'll give the test a shot with a prism-style optic this summer. The biggest challenge is being able to see through the frost on the optic when it's negative "x" degrees. I'd imagine the only way to get around this would be to have the ambient temperature be the same as the optic.The idea of building a climate chamber around an optic is neat but would be difficult to execute.

As far as actual effect on the end user: I don't know. I wonder what the user-experienced effect would be for EOTechs, since there don't seem to be any conclusive third party tests done with that optic. I almost feel bad for EOTech minus the facts that they lied and I could only use about half of the lens on my $500 optic due to de-lamination.
Link Posted: 4/18/2016 5:31:22 PM EDT
Couldn't you just take an aquarium and purge it with a heavier than air gas? Use one of those foam ice box's to hold the dry ice, then add the optic? Maybe put a piece of plastic over the top to make sure a breeze doesn't contaminate the atmosphere in the aquarium by wafting some of the heavier gas out allowing air in.
Link Posted: 4/19/2016 8:45:28 AM EDT
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Originally Posted By OldArmy:
Couldn't you just take an aquarium and purge it with a heavier than air gas? Use one of those foam ice box's to hold the dry ice, then add the optic? Maybe put a piece of plastic over the top to make sure a breeze doesn't contaminate the atmosphere in the aquarium by wafting some of the heavier gas out allowing air in.
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That sounds like something beyond my pay grade. The glass of the aquarium would still frost making observations difficult.
Link Posted: 4/19/2016 2:06:12 PM EDT
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Originally Posted By njb242:


That sounds like something beyond my pay grade. The glass of the aquarium would still frost making observations difficult.
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By njb242:
Originally Posted By OldArmy:
Couldn't you just take an aquarium and purge it with a heavier than air gas? Use one of those foam ice box's to hold the dry ice, then add the optic? Maybe put a piece of plastic over the top to make sure a breeze doesn't contaminate the atmosphere in the aquarium by wafting some of the heavier gas out allowing air in.


That sounds like something beyond my pay grade. The glass of the aquarium would still frost making observations difficult.


But if the camera was inside the aquarium it's lense and the optics I would expect to remain clear.
Link Posted: 4/20/2016 12:04:32 AM EDT
Watched your video and noticed you have the mount applied backwards on the Aimpoint H-1.
Link Posted: 4/20/2016 10:08:09 AM EDT
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Originally Posted By Wheezer:
Watched your video and noticed you have the mount applied backwards on the Aimpoint H-1.
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Doesn't matter which side the lever is on, it clamps all the same.
Link Posted: 4/20/2016 12:19:39 PM EDT
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Originally Posted By socommatthews:

Doesn't matter which side the lever is on, it clamps all the same.
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Originally Posted By socommatthews:
Originally Posted By Wheezer:
Watched your video and noticed you have the mount applied backwards on the Aimpoint H-1.

Doesn't matter which side the lever is on, it clamps all the same.


Yup. Also ensures that you're pushing forward on the base when you secure it instead of pulling back.
Link Posted: 4/20/2016 12:44:18 PM EDT
I've never seen one mounted backwards anywhere else, and it is not stated as being reversible in the owners manual. Not arguing with you SOCOM, just saying that if somebody is going to take a shot at a manufacturer, they should at least start off applying the mount correctly. Especially if they are going so far out of their way to make the results sound like science.
Link Posted: 4/20/2016 2:18:49 PM EDT
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Originally Posted By Wheezer:
I've never seen one mounted backwards anywhere else, and it is not stated as being reversible in the owners manual. Not arguing with you SOCOM, just saying that if somebody is going to take a shot at a manufacturer, they should at least start off applying the mount correctly. Especially if they are going so far out of their way to make the results sound like science.
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I don't want to get in a pissing match, especially with someone who has a respectable 7 posts over the course of 10 years.

I wouldn't qualify this video as a "shot an a manufacturer" by any means. I performed and documented this test on another optic, this was a "hot issue" here a few months back, and Aimpoints are allegedly the only sights that don't suffer from thermal drift.

"This is not a scientific test by any means," is a direct quote from the video as I'm discussing some of the many uncontrolled variables.

A mount's return-to-zero capability is the result of its locking lug and repeatable tension. The lug on this mount is a rectangular bar meaning it is the same (flat) on both sides. Therefore, orientation should have no effect on anything with regards to the lug. When considering what side the tensioner is on, in spec picatinny rails are symmetrical so that should be irrelevant as well.
Link Posted: 4/20/2016 3:31:16 PM EDT
njb242, don't sell yourself too short. This is one of the most scientific tests I've ever seen, considering the cock measuring that go on when discussing optics. Lol
Link Posted: 4/20/2016 4:08:29 PM EDT
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Originally Posted By GP4L:
njb242, don't sell yourself too short. This is one of the most scientific tests I've ever seen, considering the cock measuring that go on when discussing optics. Lol
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Link Posted: 4/20/2016 10:28:45 PM EDT
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Originally Posted By Wheezer:
I've never seen one mounted backwards anywhere else, and it is not stated as being reversible in the owners manual. Not arguing with you SOCOM, just saying that if somebody is going to take a shot at a manufacturer, they should at least start off applying the mount correctly. Especially if they are going so far out of their way to make the results sound like science.
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No worries. There are actually some mount manufacturers (Bobro and ADM for example) who actually say you can put the levers on either side. What's most important is that you push it forward before clamping consistently.
Link Posted: 4/20/2016 11:29:02 PM EDT
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Originally Posted By beavo451:


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Originally Posted By beavo451:
Originally Posted By GP4L:
njb242, don't sell yourself too short. This is one of the most scientific tests I've ever seen, considering the cock measuring that go on when discussing optics. Lol




I know ... he's been here like 2 months? But I'm sure lurking for 10 years
Link Posted: 4/21/2016 8:50:54 AM EDT
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Originally Posted By Fooboy:


I know ... he's been here like 2 months? But I'm sure lurking for 10 years
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Originally Posted By Fooboy:
Originally Posted By beavo451:
Originally Posted By GP4L:
njb242, don't sell yourself too short. This is one of the most scientific tests I've ever seen, considering the cock measuring that go on when discussing optics. Lol




I know ... he's been here like 2 months? But I'm sure lurking for 10 years


Totally, considering optic discussions only exist on this forum
I must say that I respect your avatar, though!
Link Posted: 4/21/2016 11:46:12 AM EDT
OP, do you have a frost-free freezer? Wonder if you could set up a camera in there, Aimpoint in the middle, target on opposite wall. Pile dry ice around Aimpoint, open freezer every so often to check temp?
Link Posted: 4/22/2016 2:59:42 PM EDT
I don't but at the time of this test I did have access to a blast freezer. Don't you think the lenses of the camera and optic would frost if put in such conditions?
Link Posted: 4/22/2016 3:44:15 PM EDT
In a blast freezer, yep. In a frost-free freezer...
Link Posted: 4/22/2016 6:24:13 PM EDT
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Originally Posted By backbencher:
In a blast freezer, yep. In a frost-free freezer...
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Missed that part
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