The Hawk optics are fully anti-glare / anti-fog coated. Unfortunately, no lens is 100% fog proof, the environment you are shooting in can play a large role in how fog prone a lens is going to be. The Hawk should not easily fog up, if you pull your eye slightly away from the eye cup you should notice it clear up.

The fog is just be caused by holding the Hawk too tightly against your eye, forming an airtight seal around the eye cup. This quickly produces a very humid environment localized around the rear lens. If you relax the seal a bit, you should find it works much better for you. You don't need a lot of space, just enough that the cup isn't airtight. If you are still experiencing fogging please contact us and let us know.

You can also use an Eye Cushion on your Hawk to provide extra comfort and better air flow. You can purchase eye cushions for your Hawk here - http://www.letusdirect.com/cart/hawk-eye-cushion.html