Thermal targets?

[berettaprofessor]

Picked up an AGM Thermal scope yesterday and like it. But immediately presented with a problem. Bore-sighted in daylight, which worked really well, put the shots on a 12X12 piece of paper at 50 yards, but having a bit of trouble zeroing further since I don't have the rifle locked in a stable rest. What do you recommend for thermal targets for daytime zeroing around 50 yards? Is there a cheap make-it-yourself work around?

Really digging the thermal. Beats the heck out of the cheaper NV scopes. I had a Sightmark Wraith 4-32 and just traded it off because I didn't like it.

 

[Double Naught Spy]

Congrats on the AGM! Which one did you get?

Many things will work.

I use my steel targets that have been heated in the sun for about 90% of sighting in a thermal scope. Next, I use a Hot Hands handwarmer (small) which makes a nice 2x2 target for use at 100 yards. You can actually trim these and tape them shut to make smaller thermal targets, but that gets messy.

Other things that work...
Air conditioner duct aluminum tape (reflects sun's heat and will appear hotter or cooler than surrounding surface)
Aluminum foil can be used in the same way (I have trouble with this on cloudy days, however)
Black duct tape on a white paper background allowed to heat up in the sun (the black tape should be hotter than the white paper)
Ice cubes
Frozen water bottle
Frozen fruit
Shoot a hole in a cardboard target and insert the butt end of a lit cigarette in the hole and the lit end is your tiny thermal target. You can use a punt or incense stick for an even tinier target, which might be great at 50 yards. Just don't let the cigarette or punt burn into your cardboard target and catch it on fire.

You can literally use anything that is hotter or colder than the surrounding surfaces.

 

[Bottom Gun]

I drew a plus sign on cardboard with a felt pen then pasted thin strips of tin foil on top of the lines I drew. I left a gap in the foil where the lines intersected in the center so I could fine tune my group using my spotting scope. My target resembled a duplex reticle with the thick portion of the reticle being tin foil strips.
I zeroed at 100 yd with no trouble at all.

 

[berettaprofessor]

Thanks for twi great suggestions. I got the TS25-250. Nice image, better than I expected by far.

 

[jmorris]

I have used water bottles before, either hot or cold, prefer the 8oz ones.

Last time I did it, I just used my little steel bullet trap behind my target and quarter it.





A coin from you pocket generally shows up pretty well too, you can tape them to just about anything.

 

[berettaprofessor]

Well, today I tried B/W paper targets, a penny taped to one, X's with electrical tape and with aluminum duct tape. All pretty underwhelming for visibility. I'll try a pocket warmer next.

 

[bearcreek]

Wait, so this thermal scope won't work with a target that isn't a different temperature than it's surroundings? I've used thermal monoculars but not thermal scopes. Is that the case with all thermal scopes, or just this particular model?

 

[JohnKSa]

That's basically how all thermal scopes work. It's not quite as simple as everything being the same temperature, but that's the general idea.

Thermal scopes detect the radiated thermal energy from things in their field of view. If all the items in the field of view are radiating the same level of thermal energy then the entire field of view will appear to be the same shade and no details will be visible.

Things that are hotter or colder than other items around them will show up in the thermal scope.

Things that radiate thermal energy more effectively will show up differently in the scope compared to things that radiate thermal energy poorly, even if they are the same temperature. This is why metals feel colder than plastics even when both are the same temperature.

All of this is pretty different from normal optics. Normal optics, and our eyes, are usually detecting the light reflected from objects and seeing the wavelengths (colors) that they reflect best if they are illuminated with white light. We also see things that radiate light, but a lot of what we see, most of what we see, actually, is reflected light that is bouncing off items. Thermal scopes can see reflected thermal energy, but mostly they see radiated thermal energy--the heat energy that things are either generating and radiating or the heat energy that they have soaked up and and are re-radiating.

 

[shoobe01]

Aside from actual hot targets, you can cheat and use reflection. This is common for IFF markers, etc. The sky is always cold (because space!) so you get something reflective (aluminum tape, just tin foil glued on...) and tilt the target ever so slightly back until you can see sky, get a dark spot or cross-hairs.

They also make thermal targets. Never used one, but plenty exist so the Amazon one is just an example, check on your favorite gun stuff purchase site.

Amazon.com

If it makes you happier to stick with OEM gear, note that AGM (as all others do) makes thermal zero targets also:

https://www.bhphotovideo.com/c/product/1750980-REG/agm_633125s1_thermal_targets_pack_of.html/?ap=y&ap=y&smp=y&smp=y&smpm=e_f83mkz_uar&lsft=BI%3A514&gclid=CjwKCAjwkNOpBhBEEiwAb3MvvV4OUzbizzUDCKID5tdkQYwgWgTI9bhgO-ELYryGSb9WkDQFMSwV_hoC8gQQAvD_BwE

 

[bearcreek]

That's basically how all thermal scopes work. It's not quite as simple as everything being the same temperature, but that's the general idea.

Thermal scopes detect the radiated thermal energy from things in their field of view. If all the items in the field of view are radiating the same level of thermal energy then the entire field of view will appear to be the same shade and no details will be visible.

Things that are hotter or colder than other items around them will show up in the thermal scope.

Things that radiate thermal energy more effectively will show up differently in the scope compared to things that radiate thermal energy poorly, even if they are the same temperature. This is why metals feel colder than plastics even when both are the same temperature.

All of this is pretty different from normal optics. Normal optics, and our eyes, are usually detecting the light reflected from objects and seeing the wavelengths (colors) that they reflect best if they are illuminated with white light. We also see things that radiate light, but a lot of what we see, most of what we see, actually, is reflected light that is bouncing off items. Thermal scopes can see reflected thermal energy, but mostly they see radiated thermal energy--the heat energy that things are either generating and radiating or the heat energy that they have soaked up and and are re-radiating.

I understand how the thermal part works. I just didn't realize that the reticle itself was dependent on that. I had an idea that one could use a thermal scope with the thermal capability turned off. Not sure where I got that notion. Seems like that'd be a real useful feature for somebody to invent though.

 

[JohnKSa]

I just didn't realize that the reticle itself was dependent on that.

I'm not sure what that means. The reticle should be visible regardless of anything else that's going on.

I had an idea that one could use a thermal scope with the thermal capability turned off.

Don't quote me on this, but I think there was at least one company that had a setup with a scope that would overlay both thermal and visible light views. It's certainly not a common feature.

 

[bearcreek]

I'm not sure what that means. The reticle should be visible regardless of anything else that's going on. Don't quote me on this, but I think there was at least one company that had a setup with a scope that would overlay both thermal and visible light views. It's certainly not a common feature.

Now I'm more confused I guess. My understanding from the OP was that he needed a "thermal target" in order to zero his new scope. If the reticle worked regardless of anything else going on, why would he need a special target setup?

 

[JohnKSa]

Because typical targets don't have differences in thermal radiation that can be detected in the scope. You can see the aiming reticle, but there's no clearly defined aim point to aim at.

When we aim at paper targets with normal optics, the light reflects differently off the ink on the targets than from the rest of the paper and we can line up the reticle on the inked features on the target. When using a thermal scope, the ink typically doesn't change the thermal radiation properties of the paper enough to allow the inked features to be seen in the scope. The entire target appears to be one big blank sheet of paper. That means there's nothing to line up the reticle on--nothing to aim at. So something needs to be added that will radiate heat differently from the rest of the target to provide an aiming point to align the reticle with.

 

[Double Naught Spy]

Wait, so this thermal scope won't work with a target that isn't a different temperature than it's surroundings? I've used thermal monoculars but not thermal scopes. Is that the case with all thermal scopes, or just this particular model?

I understand how the thermal part works. I just didn't realize that the reticle itself was dependent on that. I had an idea that one could use a thermal scope with the thermal capability turned off. Not sure where I got that notion. Seems like that'd be a real useful feature for somebody to invent though.

The reticle isn't depending on anything in the thermal scope on most thermal scopes. The reticle exists only on the near eye display inside the thermal scope and is overlain on the image from the thermal sensor. The same near eye display and reticle could be used on a digital night vision scope as well. The only reticles depending on the thermal image are those by N Vision and Trijicon (BAE cores) where the reticle always appears in a contrasted color to the background behind it. So if you are on white hot and the reticle passes over a hog, the reticle will turn black so that it stands out against the hog behind it.

As JohnKSa noted, all the thermal scopes work off of temperature. There are a few that have fusion capabilities, usually paired with digital NV (which some are useful in daylight) and one company went for the triad of trying to blend a daylight channel, night vision channel, and a thermal channel all together, or any pair or single channels may be used. Previously, these have been overly expensive and not gained much ground in the hunting or self defense communities. Now, you can find something like the Pulsar DUO that has the triad capabilities, but only as 2 channels. You get thermal with digital daylight or with digital night vision. https://pulsarnv.com/products/thermion-duo-dxp50

 

[HKGuns]

Some of the points being made here are why I went with a clip on.....Mounts to any of my railed rifles and I maintain the existing zero.

I used hand warmers to verify the existing zero's worked with a few of my scopes. No issue at all. Even works with the EOTech's.

The main drawback is the forward weight.

 

[jmorris]

Wait, so this thermal scope won't work with a target that isn't a different temperature than it's surroundings?

Yes, they are all but useless looking for cold blooded animals as they are the same temperature as their surroundings.

 

[Double Naught Spy]

Thermals have no trouble seeing poikilothermic (aka "cold blooded") animals, so long as they are a different temperature than their surroundings. Homeothermic animals generate their own body heat. Poikilothermic animals regulate their body temperature by behavior. When they are too cold, they will seek out heat to warm themselves. When they are too warm, they will see shade or cooler locations.



The trouble with poikilothermic animals such as snakes is that they get their body heat from the environment. So, if they have been in the same spot for a longer period of time, there is a good chance that they will be the same temperature as their surroundings and so not stand out on thermal. If they are on the move and crossing ground that is a different temperature than them, they will stand out. So snakes can be a challenge.

I have seen hogs that were nearly invisible to thermal as well after taking a dip in the water.

 

[TonyAngel]

Congrats on the AGM! Which one did you get?

Many things will work.

I use my steel targets that have been heated in the sun for about 90% of sighting in a thermal scope. Next, I use a Hot Hands handwarmer (small) which makes a nice 2x2 target for use at 100 yards. You can actually trim these and tape them shut to make smaller thermal targets, but that gets messy.

Other things that work...
Air conditioner duct aluminum tape (reflects sun's heat and will appear hotter or cooler than surrounding surface)
Aluminum foil can be used in the same way (I have trouble with this on cloudy days, however)
Black duct tape on a white paper background allowed to heat up in the sun (the black tape should be hotter than the white paper)
Ice cubes
Frozen water bottle
Frozen fruit
Shoot a hole in a cardboard target and insert the butt end of a lit cigarette in the hole and the lit end is your tiny thermal target. You can use a punt or incense stick for an even tinier target, which might be great at 50 yards. Just don't let the cigarette or punt burn into your cardboard target and catch it on fire.

You can literally use anything that is hotter or colder than the surrounding surfaces.

Man, I never even considered using a cigarette or cigar ... and I'm a smoker.

 

[jmorris]

I have seen hogs that were nearly invisible to thermal as well after taking a dip in the water.

Most of the large ones we come across have “cold spots” where they have caked on mud.

 

[shoobe01]

In the bad old days of mechanical scanning and stuff the thermals had big dials and you could mess with the way the view worked, but today they are much easier to use, BUT also do their own thing and knowing what helps to use them better.

On many occasions I have seen targets (animals or people) disappear, or know they are there, but cannot see them despite the magic of of MWIR in my hands. Because the automatic gain control adjusts to the wrong nice average. Try it sometime: Look at some animals on a treeline a couple hundred yards off, and move up and down, so there is lots of sjy, and pan down to lots of ground.

The lots-of-sky will overwhelm the scene and make all the warm stuff wash together so various warm things blend together. Pan down and suddenly hot targets pop out.

 

[a_canadian]

A candle burns for a while. Beeswax much more slowly than paraffin. A piece of 1/4" mild steel bent into an L shape, hung on whatever frame, with a candle burning an inch or two below the main target circle, the flame hitting the L tab, would heat the whole plate quite evenly after a few minutes. Warmth moves upward, and metals conduct heat, so while too large a plate wouldn't warm thoroughly, something like a 4" or smaller plate should work well enough for establishing a decent zero. Of course you might accidentally hit the candle... but hey, it's just a candle, put up a new one, and adjust your optic by the distance you were shooting low, as you hit the candle. And the candle sitting slightly behind the plate, under the L bend, would prevent it from being blasted by bullet splatter.