At 01:01 5/28/00 , Mike Swain wrote:
>>From the film results I've seen polarizers are perhaps the best thing going
>for both more vivid color and for better contrast in B&W, but I see little
>mention of them as being as useful as they are. Is there any merit in
>paying for top brand ones, or are they pretty much all alike?
Two biggest reasons for using a polarizer:
(a) Glare reduction of specular highlights from light incident to
non-conductive reflective surfaces. Note this is not _elimination_ which,
depending on subject and context, can look unnatural and flat.
(b) Deeper blue sky and higher contrast with clouds, but this works best
with sky that is 90 degrees to the sun.
Yes, there is a difference in quality. I had the cheap stuff a long time
ago and dumped them for better ones. It made a noticeable difference in
the images produced. IMO the best filters on the market are made by B+W
and Heliopan. [B+W is owned by Schneider-Kreuznach, a German lens company
running a close second to Carl Zeiss and noted for exceptional cinema and
projection lenses.] Both use Schott optical glass in their filters.
[Schott is part of the Zeiss Stiftung (Foundation).] There are other good
ones I've used such as Vivitar "VMC" and Hoya "HMC" (coated) along with a
couple with the Olympus name on them. They also have good optical glass in
them. There is debate about what you gain with a multi-coated versus
single-coated filters. However, even a single coating is much better none
at all! And this, IMO, is what cheap filters really lack (in addition to
their rings). Multi-coated ones can be expensive, perhaps too expensive
for what you gain. The three Olympus filters I have are all coated and
from what I can tell it's a single coating. Note that certain types of
special filters, such as soft focus, fog, star, etc. are uncoated, even by
the top makers. Yes, the top filter makers have coated polarizers.
I "dumpster dive" the used filter bins for Heliopan and B+W filters, but
still am finicky about their condition if I find one. Picked up a good
Hoya "HMC" a while back. Most recent find? Three B+W 55mm (4X Cross, Soft
Focus #1, and Soft Spot Lens), and a Heliopan 49mm (Soft Focus #1).
What's important to a filter?
(1) Accuracy of its color (if it's a color correction, etc. type filter).
(2) Precision of flatness and parallel surfaces of its glass.
(3) Optical quality of glass used (internal dispersion and absorption).
(4) Optical coating for light transmission and flare reduction.
(5) Precision and quality of the filter ring to get the filter optics
perpendicular to the lens axis, keep it that way under repeated use, and
not cause excessive wear to the lens ring. IMO brass is best, aluminum
runs second but can stick easily making removal difficult, and forget about
plastic.
(6) In use, keeping a filter _clean_ is as important as the first five.
[Token OM Content]
When you put a filter on the fine Zuiko you sweated over while bidding top
dollar for on eBay . . . and worked so hard to sneak into the house
afterwards [oh, the angst of it all] . . . you are adding another element
and group to the lens. Since all the light must first go through the
filter to get to the lens itself, why put a comparatively poor piece of
optics in front of a fine piece of optics? It defeats the purpose of
having a good Zuiko!
-- John
< 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 >
|