They are second-to-none in optics, and own(ed) the
patents for things like multi-coated lenses and
non-glass optical elements (i.e. flourite, quartz).
Their association with Sony is from their early
association with Yashica, who bought the Contax
product line from Zeiss (then I think were bought by
Konica, who also bought Minolta, they were bought by
Sony.
If you have an old person in th family, they probably
have heard of the Zeiss Ikon viewfinder cameras.
They also make eyeglass frames (bought Titus Optical
in the eighties), eyeglass lenses, lab equipment
(spectrophotometers, white scales), industrial
measurement machines, surveyor equipment,
electronmicroscopes , telescopes, microscopes,
planetarium projectors, and a bunch of other stuff.
They still make lenses for Hasselblad and other fine
cameras. Every picture from the moon (and virtually
all from manned space missions) went through Zeiss
lenses.
Carl Zeiss (the company) was one of the first to give
their employees things like time off and a ~40 hour
work week, vacations, and other benefits (~170 years
ago).
I worked for Zeiss 1979 - 1983, it was fun, I liked
it. I also got some binoculars and some other stuff.
I would like to add to the growing line of people to
point out that calling your friend an idiot is
actually in insult to people that are merely idiots.
Please kill your friend before he spreads his genetics
into the common pool.