Another important thought to consider when using any thermal weapon hunting scope is the diurnal cycle of inanimate objects absorbing IR radiation and subsequently irradiating IR radiation.
There are crossover times during a 24 hour period of time when inanimate objects (grass, trees, rocks, ground, water, etc) absorb sunlight and then re-radiate that light as IR.
Once you get accustomed to this aspect, you can adjust your thermal hunting times to coincide with the best diurnal crossover points to allow for maximum performance from your instruments.
I am constantly hearing about this and that regarding costly useless thermal instruments from newbies who just took their scopes out and everything was white-out or too hot or way too unresolute.
Where I do most of my hunting, unless we are under a high pressure dome, you can bet that the fog will set in about midnight. Thermal still works good in fog but not as good as a high pressure no fog. so maximum range and resolution is going to be affected. Just another reason why I PLAN my hunting times to coincide with maximal effective times at night, and also to take into accord the maximum emission of the diurnal crossover points of thermal absorption and emission of the millions of inanimate objects in the woods, simply because I am after only the animate ones.
If you plan your hunt times accordingly, you will be surprised how much more enjoyable it is instead of trying to hunt at minimal thermal productive times...