The cold wreaks havoc on em for sure. I had a Leica CRF that wouldn’t range caribou at 500 yards in the cold. I had a Zeiss PRF that wouldn’t range a wolf at 400 ish in the cold. Both incidents had temps below zero and not much above zero degrees. I’ve learned that when hunting in cold weather I keep the rangefinder in an interior pocket if I want accurate readings and performance.