What adjustments do you make on your thermal for (cold) fog or snow?

[RZR800XC]

We've had an oddly warm winter so far, and around my part of ND the past few days has been in the low 30's with pretty thick fog most of the day. The sun hasn't been out to warm things up, so it's like having a cold blanket over everything with little to no contrast. I went out on the porch and looked around with my scope last night and couldn't even make out my shop 50 yards away.

What, if any, adjustments do you make on your thermal scopes to get a better picture in the fog or when it's snowing? I have options for Gain, Contrast, Sharpness, and a few others. I am using a Flir Zeus 640 75mm and a Flir Thermosight Pro PTS233 and typically have been running white-hot. Do different color palettes work any better?

Or do you just roll with it, and pick out the heat signatures against a solid gray backdrop?

 

[Kirsch]

Well, first of all thermals all struggle in high humidity and fog is about the worst. Not to be mean, but on top of this, the PTS233 struggles more than most in less than ideal conditions. The thermals I run such as the Hogsters and Phenom from Bering Optics handle the humidity a lot better but are not immune to it either.

General rules of thumb are to attempt to increase the contrast. Yes, different color palettes can help with different thermals also. Some thermals have a High-Humidity mode. The Flirs didn't from what I remember but they do have tons of different settings to tweak. I would play around and write down the settings if you find one you like for these conditions.

Even in really rough conditions, the coyotes will still often show in the thermal but not much else will. This can make it difficult to pick a calling stand if you can't see the terrain enough to know where to sit, place the call, etc. If you have called from the spot before and know the lay of the land it can be OK.

The last thing to mention is danger. With the thermal view being very limited, it can be dangerous if you don't know what is behind the target. Just stressing, if you are hunting in really tough thermal conditions, make sure to know the area really well.

 

[Ernest49]

At the end of October 2019 I went, in the middle of the night, to retrieve a backpack (with documents) that my hunting companion had forgotten in the countryside during the day. There was a very dense fog with relative humidity close to 99-100%. I took the Pulsar Accolade XP50 lrf with me. I had to set the contrast to the maximum level of 20 and the brightness to 13-14 in warm white mode. I managed to see 3 hares a short distance away in the fog. But obviously the laser night rangefinder didn't work. He scored 12 yards in any direction. Evidently the laser beam was immediately reflected by the microscopic droplets of the wall of fog in which I was immersed.