Home Forums Hunting & Shooting Hunting Optics Objective lens fog

Does anyone have trouble with their objective lens fogging on cold mornings? When I say cold, a cold morning here is usually around 28-30 degrees. I have had a few times this has happened before. I recently bought a scope with a 56mm objective lens. I hunted with it two mornings this week and it developed a hazy fog both mornings. This fog occurs on the outside. I've had it happen that there may be a little in the center of the lens but never the whole lens.

Occasionally yes, depends if the gun is brought from a warm to cold temperature, I haven’t seen a scope yet that wouldn’t do this, from cheap one to the best glass.

I think this is why BUSHNELL RAINGAURD was created. It doesn’t keep your lenses from fogging up but when you look through the fogged lens you can still make out an image where as other non RAINGAURD treated lenses you can’t see anything.

That is why we leave ours in the truck outside at deer camp.

Leave mine on the porch for that same reason

Yes. It has happened to my scope and bino's at that temperature.

Hogwild7 and plumbum have the answer. leave them locked in the truck or outside in a safe place. They only fog up when going from a warm temp to very cold.

I will try and see if this works. It doesn't do it when I first go out. It does it after I set in the stand after an hour or so.

Fogging on the outside is condensation.
A cold object will cause warmer moist air to condense on it.
Therefore, a cold gun into a warmer environment would result in the worst fogging.


Keep you gun the same temp as the environment and there is no greater chance of the ocular collecting condensation as there is the rest of the objects outside.

I've probably seen it more on the ocular lens than the objective lens, but it is always my fault for either breathing on the lens when I'm about to take a shot or resting a cold rifle across my thighs and the heat off my legs condenses on the cold surfaces. I've pretty well solved the problem by using those flip up Butler Creek Storm covers (the ones with the clear glass windows) and by hanging my rifle on a limb or peg away from my body heat. Fogging in our scuba masks was solved by using some liquid stuff they sell or by spitting on the insides of our masks and rubbing it around. I not sure what that would do to a scope coating, so proceed with caution.