A:AnswerI didn't experience any fog while using these. I've used them indoors and outdoors as well as with and without glasses. They have a cool feature where you can pop out the eye piece to great some distance between your eye and the lens. I think that helps keep the fog away.
A:AnswerWe don't have a seven year old to measure, but the range of the width of the distance between the two eye lenses, is 2 1/4 inches and 3 inches. Hope that helps