When running a clip on NVG in the South, especially this time of year we get a ton of lens condensation, and condensation on everything else. I was reading on some astronomy forum about making use of such a heater to avoid this issue. I’ve tried cat crap and can be lacking.

If it is safe for telescopes and cameras, I assume it would be GTG for a clip on?

Something like this

https://www.amazon.com/dp/B003UNN8Z8

Anyone have an experience with one of these type units?

http://philhart.com/content/dew-heaters-night-sky-photography

Not sure on NV or thermal if a lens heater could or would “unevenly” heat the individual lens or complete lens assembly to a point of noticeable distortion or lens element separation.

As in this picture, on a large front element/fast lens, if that front element is heated to point that is much warmer or hotter then the other elements in the lens, I could see it distorting the image. It might just be a tiny bit but that could be enough.

I would look into what and how the astro photographers comment on this solution.

Just my thought coming from a few decades in the pro photo biz.

I don’t really have the issues with the thermal. Even if it has some condensation on it, it still works. NVG is another story.

I found a 5v USB adjustable output lens heater on amazon that I ordered. I got some adhesive temp stickers to stick on the optic so I can play around with the temp and see how much of a difference it makes. After a bunch of reading, folks have been doing this on cameras and telescopes for some time with no ill effects best I can tell. It shouldn’t need to be warmed that much over ambient, so we’ll see....

On very humid hot days, when my air conditioning has already cooled my gear and made it prone to condensation, I will leave it outside on a chair for a half hour or so to prep it for my outing and reduce fogging.

I always stick my stuff in an open garage prior to going out for a few hours if I have the time. Never run the AC or heat in the ride, windows down. Still have issues.

Not to derail your topic, but have you tried some good anti fog wipes?  We carry them with us here in Indiana in the summer (gets pretty humid as well).  They usually do a good enough job, especially if I have them farther off my face than normal.  Worth a shot if you havent tried that yet.