Prisms are heavy. Why not replace the four prisms in a porro binocular with eight dielectric mirrors?
I would think alignment would be next to impossible with 8 mirrors.
maybe I'm wrong?
Cheers
My one and only experience with mirrors versus prisms in a binocular came about in the early days of ebay. I bid on a 8x30 porro appearing binocular for 20 bucks including postage. The seller was a real BS artist, extolling the pristine condition of the binocular. It was one of those plastic glued together replicas. Looking through it was like looking through the bottom of a Coke bottle. So I took a hacksaw to it to look at the innards .Where prisms normally would have been were four mirrors. It produced a lot of laughs with my optics buddies.
John