I think the use of PL by some manufactures goes way back, there was once
a standardized filter nominclature, that used letters, A for red, K[#]
for Yellows, G for Deep Yellow. I don't know all of them, (One often
sees the letter designation combined with the Wratten number used by
Kodak, which can be confusing as some Wratten numbers include a trailing
letter. So an A filter is a Wratten #25 which is described as red
tricolor, and might be designated by say Tiffen as an A-25, while, a
lighter red filter has a Wratten number of 23A.
I always assumed that the the PL designation for a polarizer was used
because "P" conflicted with some long forgotten standard letter code for
a color filter. CPL was just a logical extension from that. I have no
idea why some manufactures decided on A for red, K for Yellow or G for a
specific shade of Deep Yellow, nor could I find a complete listing of
alternate letter codes for different photographic color filters, so this
is just speculation on my part.
It does make sense in a way. Polarizing filters were a relatively late
addition to the photographic arsenal using them on non SLR cameras was
tricky, some of the Rube Goldberg solutions to using them with
rangefinder equipped cameras look fragile at best, and the Graflex style
reflex cameras viewing screens were already so dim that focusing and
composing with a polarizer in front of the lens seems impractical. So
it seems that P might have been used for some color.
On 7/23/2015 10:32 AM, Igor PDML-StR wrote:
Hi Darren,
So, the initial "PL" was for PoLarizer (as Bill suggested)?
That's weird! But those things happen...
I am recalling that when I saw "PL" many years ago, I actually thought
it could've been for "Linear Polarizer" but possibly in a different
language (e.g. French), where the word sequence is reverse (polarisant
lin'eaire).
As for varios markings for Cirular Polarizers, I found that at least
two companies/brands also used "PLD" (Quantaray) or "P.L.D." (Marumi):
http://www.bhphotovideo.com/c/product/800690332-USE/
Any idea what that "D" stands for? And why it is writed with the
periods (dots?) as an initialism?
http://www.marumi-filter.co.jp/en/product/02/dhg_s_cpld.php
(You can see it engraved on the filter.)
In the letter case, it is funny that they write "Circular PL" on the
website.
Now, my 3 guesses that I mentioned yesterday but didn't write to avoid
any bias were: lens, light, and luminescence that would be in the
scientific term "circularly polarized luminescence". Obviously, none
of these would be correct in "CPL filter".
Igor
Darren Addy Thu, 23 Jul 2015 04:44:15 -0700 wrote:
It isn't an acronym. PL was originally the abbreviation printed on
linear polarizers from almost all manufacturers. When circular
polarizers came into being (and were necessary to avoid exposure and
focus problems with modern cameras that use semi-silvered mirrors or
prisms to split the light entering the viewfinder in order to
calculate exposure and focusing distance) they had to be
differentiated in some way. You will see them called CPL, PL-CIR, and
PL-C (perhaps others) by various manufacturers.
--
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immortality through not dying.
-- Woody Allen
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