Do they have BAK4 glass? Are they water/fog proof? — 1 Answer

They are BaK4 prisms--note the lower case 'a'. 'A', it is my understanding denotes Schott glass, only available (or used to be) on German optics. And unfortunately they are neither waterproof nor fog proof, the only basic drawback with them, as I compared them directly with several roof 10x42s, and they performed equally to them all, even a pair costing 4x the price. Yet, since all of those were waterproof, in the long run they were more likely to fend off fungus that could possibly establish themselves on the interior of the unit. Therefore the roofs were superior for that reason alone. I own the Aculons and in dry weather use them more often than the dachs: they have that cool old-fashioned look and feel of the zigzag chassis of your grandpa's binoculars. I would rate them 4 stars only for the lack of a complete seal; otherwise, if you have no practicable use for it, you can save plenty of cash by going with the Aculons. They will serve you well, I (and Nikon, which, btw, has very good cust. service) dare assure you.