On Tue, 8 Dec 1998 16:47:20 -0800, "Charles Loeven" <cpl49@xxxxxxxxxxxxx>
jammed all night, and by sunrise was overheard remarking:
> <<Yes and no. The circular polarizer is needed when a beamsplitter is
> present in the mirror assembly of a camera, since this beamsplitter
> itself is a kind of polarizer, so it won't properly see the light
> output from a normal linear polarizer.>>
> Thanks Dave. This is the easy answer I was looking for. :-)
If anyone out there hasn't seen the effect this situation describes,
take two linear polarizers and rotate one against the other. This gave
me hours of entertainment as a kid anytime Mom's polarized sunglasses
broke :-)
> I believe spot meters were common long before circular polarizers were,
> or beam splitters for that matter.
I don't if "common" is the right word, as least related to built-in
meters (you could get handheld spot meters, which are basically just
normal handheld meters with optics, for years). The spot meter, as it
exists in any SLR, is simply a sensitivity pattern focused in the center
(usually) of the viewscreen. There are lots of potential patterns (some
of the super-smart Nikons and Canons claim to use libraries of hundreds
of weightings, based on the feedback they get from multiple independent
sensors), and lots of ways to get them. None of these, far as I can tell,
necessarily
require a beamsplitter. Though these days, especially with OTF metering
a long-proven technology, it's still not uncommon. I haven't checked out
the competition enough to know or really care how they're doing it.
But the short, simple answer is that there's no need for circular
polarization just because you have a spot meter. There is just because
you have an OM-4 (in my case). Again, I don't know the OM-2000.
--
Dave Haynie | V.P. Technology, Met@box Infonet, AG | http://www.metabox.de
Be Dev #2024 | NB851 Powered! | Amiga 2000, 3000, 4000, PIOS One
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|