From       : Bobs31@aol.com
Subject    : Re: [q] Polarizing Filter differences....
Date       : Mo 26.06.95, 22:40  



You are getting a lot of myth so perhaps some facts will help.

First we are the Heliopan distributor in the U.S.
To become the Heliopan distributor we had to stop being the B+W
distributor.

We are also the Rollei, Rodenstock, linhof and Minox distributor for the
U.S.. All of these companies sell filters as well and we are deeply
committed to high quality filters.

There are many differences in polarizers. But to be able to chose
intelligently you need to understand what types are available and how they
are made.

Polarizers are available as follows for cameras:

1, Standard type circular or linear uncoated
2, Standard type circular or linear coated
3, Standard type circular or linear with more than a single coat but not
multi coated
4, Standard type circular or linear multi coated

5, Any of the above in an aluminum ring this type of mount is prone to
jamming
6, Any of the above in a plastic ring. This type of rim can cross thread,
or jam.
7, any of the above in a brass ring
8, any of the above in a brass calibrated ring.

9, Circular and linear polarizers are also available in a Kaesmann or
tropicalized version. This is a polarizing foil that is streatched to
ensure optimal flatness and edge sealed in glass to eliminat damage from
moisture, fungus, etc. These are the sharpest polarizers available as the
foil is the flattest and are the least likely to effect focus with long
lenses.
10, Polarizers are available in several different grades from
manufacturers like Polaroid. Some are totally neutral and some are not. A
polarizer should not effect or cause a color shift unintentionally. And a
cheap polarizer may not be neutral.

There are also special polarizer types. For instance a warming polarizer.
This combines a skylight filter with a polarizer, linear or circular, to
warm and polarize at the same time without having to stack filters. You
can also find the same type of construction from some companies with a
green filter combined with a polarizer for B&W work.

In addition there are other factors such as the quality of the glass, how
flat it is, quality of the laminating material, freedom from dirt/dust,
etc. between the layers.

Tiffen primarily makes uncoated filters in aluminum mounts and on special
order can supply some filters with multi coating. The lowest priced Tiffen
filters in the magazines are uncoated.

Heliopan supplies coated (4 layers) or multicoated (14 layers) in
calkibrated brass mounts in all types listed above except for the
green/Polarizer combination. The calibrations on the rim indicate the axis
of the polarizer and make using a polarizer on a rangefinder camera very
simple.

B+W uses similar coatings and rings as Heliopan but are not calibrated.

Hoya offers coated and multi coated types primarily in plastic mounts and
sometimes in metal mounts.

If you would like further information I would be happy to send you the
Heliopan filter brochure.

Bob
Bob Salomon, HP Marketing Corp., Giottos, Gepe, Heliopan, Kaiser
Fototechnik, Linhof, Minox, Rimowa, Rodenstock, Rollei, Silvestri

If you have any question, remark, comment, want to share some philosophy or just want to express your opinion about these pages, feel free to send email to: w.j.markerink @ a1.nl