Do you think it is realistic for bino's to be sitting out in 20 degree temps for 24-36 hours without receiving any heat source?
The human body puts off +/-350,000 joules of energy every single hour. For some context, it only takes about 1,900 joules to raise the temperature of 16 ounces of water about 2 degrees F. Solids, such as aluminum (common material for binocular chassis), has a specific heat that's about 20% of liquid water, which means less energy is needed to change temperatures.
So my point, if guys wear their bino’s on their chest, their bino's will likely never experience 20-degree temperatures for 24-36 hours....unless the guy wearing them is dead.
Also, while I was at the range, my chrono froze (literally had frost covering it), and stopped working. My phone also stopped working. So while it's only anecdotal at this point, it was good to see that my bino's still worked fine. This hunting season will be a better indicator for me.