BaK4 vs BK7 prisms

I was shopping for binoculars recently, and in the process of researching what to buy I saw a big fuss about BaK4 (barium crown glass) prisms. The Internet made many vague claims of "sharper" and "expensive therefore better" in comparing BaK4 to BK7 (borosilicate crown glass), but what is really happening?

Joshua Tree

Yesterday we rented some equipment (tent, sleeping bags, mats, cookstove) from the Caltech Y, packed everything into the car and drove out to Joshua Tree. 

Binoculars

Bought a pair of Celestron 8x42 binoculars last weekend ($64, Woodland Hills Telescope). The pictures make them look smaller than they actually are; remember that the objective lenses are 42mm in diameter. The width feels pretty nice, but they are a bit longer than I'd like.

The good

Parrots!

Red-masked parakeets, actually. I'd seen them at this same location the first day after I moved in to Caltech and have been on the lookout for them ever since.

Telescope

I bought a telescope yesterday! It is a Meade 70AZ-A, a 70mm refractor with a 600mm focal length (f/8.5). I got it for $70 from Woodland Hills Telescope (the brick-and-mortar version). They were pretty busy when I was there, but they're nice and have a good camera/photo department as well.