Dude, I don't know. Someone smarter than me would have to answer that. I just know that they don't work as well during the daytime because everything in the woods is hot during the day. I was looking in Kansas and you could barely see a deer right in front of you because the wheat field was as hot as the deer!
A few weeks back it was kinda foggy and I couldn't tell if it was a hog I was looking at or not at night. I do have a hog permit for that land. I didn't shoot because I couldn't tell what it was. I grabbed my trusty .308 with the Night Vision and looked down and it wasn't loaded. I just zipped it back up.
My issue with a lot of Night Vision devices is they have TOO much magnification. When you are seeing a hog at 20 yards in the woods, they fill up the entire scope! In the open fields I can snipe better with a Night Vision than I can with a Thermal. In the woods though the Thermal is without peer. There is a place on the property that I can see 210 yards like daylight with a Night Vision. That is where the low zoom of my Thermal is an issue.
The other problem is with the Thermal it seems like sighting it in isn't a precise. I can tell zero difference in accuracy with my Night Vision and my day scope. I have one of those new ones that you can use day or night and I love it! During the day it is a nice color scope, flip a switch and it is a Night Vision. I would never take that on public land though! That is why I'm telling you that someone smarter than me needs to answer this. I am actually thinking about mounting that scope on my PCP air rifle for squirrel hunting so I can record the shots.
