i have heard about this if you look at some of the reviews on your rangefinder you might find that problem in the reviews..Just google your brand for reviews..I was gonna purchase a well known rangefinder until i read the reviews and they said inaccurate readings in fog,misting rain, and through the shoot through messh ( which it is suppose to range through).. IHave also heard about the lenses getting foggedd up at the moment of truth, but im skeptical about that because they could have easily breathed on it ( in cold weather) as they brought it up to range the deer, creating fogged up lens..