Interesting group of optical material from the collection of Otto Berg, including: a "certified precision grating" mirrored optical piece by Baushch & Lomb, with label indicating "1200 grooves/mm"; a slightly larger grated mirror piece on a metal bracket baseplate, unmarked; a clear 4.5″ diameter glass lens; a 5.5″ diameter red glass filter; and a 5″ diameter optical piece inset with three threaded mounting points, with tapered edges. In overall very good to fine condition.
From the collection of Dr. Otto Berg.
