Polarizer filter

"Sampson" wrote in message
news:mer7c.54680$J05.428657@attbi_s01...

snip

Phil are you saying that software can do it now and no need for a
polarizer? I have read this is the case from some but have also been
wondering if this is really true.


There is no software which can generally duplicate the effect of a
polarizer. Period. And there never will be, for a myriad of physical
reasons.

Exceptions? Su a light source of known intensity reflecting from a
surface of known composition whose orientation with respect to the light
source and camera is completely determined, for instance. Of course, you may
need several days of computer time to ray-trace the scene to get an
acceptable result for a 640x480 picture, say. Better yet, suppose glare
obscures objects lying beneath the surface of a lake when a picture is
taken. A polarizer could have removed the glare revealing the objects, but
how on earth could post-processing software fill in the non-recorded detail?

"Sampson" writes:

Phil are you saying that software can do it now and no need for a
polarizer? I have read this is the case from some but have also been
wondering if this is really true.

Sorry, no. It's just a simple question of what problems the original poster
is trying to solve using a polarizer.

--
Philip Stripling | email to the replyto address is presumed
Legal Assistance on the Web | spam and read later. email to philip@
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"Sampson" writes:

That is what I was pretty sure of but have not spent a lot of time with PS.
I was actually thinking of some shots I took with and without at the beach
where parts of the distant Caribbean Ocean were a deeper darker blue while
fish near the shore could be seen swimming just beneath the shallow water
but got just a reflection with no filter.

I saw a very nice photo someone took with a graduated filter and a
polarizer. The photographer used the graduated filter to bring the sky
down, and the polarizer to cut the reflections off the ocean, so that you
got a very nice photo of the sky, the water, and the rocks and seaweed down
in the water. Really nice shot of what we see and can't record of film
because of the great range of values.

--
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Legal Assistance on the Web | spam and read later. email to philip@
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On 21 Mar 2004 23:39:16 GMT, Zsolt wrote:

Hello,

I'm a newby to photography and trying to buy some accessories to my camera. I have a Minolta Dimage S414 digital camera.
Right now, I'm about to buy some polarizer filters. However, I can't decide: linear or circular? Somewhere I read that linear polarizers are only for older cameras, with digital you should use circular. In a digital camera how-to book I found that circular polarizer is a bad choice for a digital camera. Which is true?? Do you have any suggestions?
Any suggestions for brands? Right now I've found Tiffen and Hoya in the price range I'm planning to spend...
Thanks for any ideas,

Zsolt

Circulars are for autofocus models, I don't know if digital cameras
require any certain type, unless of course they are autofocus.

"Slingblade" wrote in message
...
On 21 Mar 2004 23:39:16 GMT, Zsolt wrote:

Hello,

I'm a newby to photography and trying to buy some accessories to my
camera. I have a Minolta Dimage S414 digital camera.
Right now, I'm about to buy some polarizer filters. However, I can't
decide: linear or circular? Somewhere I read that linear polarizers are only
for older cameras, with digital you should use circular. In a digital camera
how-to book I found that circular polarizer is a bad choice for a digital
camera. Which is true?? Do you have any suggestions?
Any suggestions for brands? Right now I've found Tiffen and Hoya in the
price range I'm planning to spend...
Thanks for any ideas,

Zsolt

Circulars are for autofocus models, I don't know if digital cameras
require any certain type, unless of course they are autofocus.

Does the camera have to have white balance control or will auto WB cameras
work as well?

Sam

In article ,
Gisle Hannemyr wrote:

Linear polarizers are more effective and less expensive than circular
ones

No they use the identical polarizing foil. The only difference between a
circular and a linear polarizer is the addition of a quarter wave plate
that is sandwiched behind the foil on a circular polarizer.

The quarter wave plate is the reason the circular is more expensive
however currently more circular polarizers are made and sold then linear
ones so that helps to bring their costs closer together.

Additionally the circular works on any and all types of camera properly
without effecting exposure, focusing or finder display. A linear may
not. So buying a linear for one specific camera to save a couple of
bucks may, in the long run, be the most expensive way should you need a
circular for another camera.

BTW, B&W is black and white. B+W is Berman and Weber the filter
manufacturer.

--
To reply no_ HPMarketing Corp.

[POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]

In on Sun, 21
Mar 2004 20:28:24 -0500, Bob Salomon wrote:

[SNIP]

Binaries (e.g., uuencoded programs or pictures) should never be posted to
discussion newsgroups; most discussion newsgroups do not permit binary posts.
Post binaries to a *binaries* newsgroup only (or on a website or FTP server),
with a notice in relevant discussion newsgroup(s).

--
Best regards,
John Navas
[PLEASE NOTE: Ads belong *only* in rec.photo.marketplace.digital, as per
http://bobatkins.photo.net/info/charter.htm http://rpdfaq.50megs.com/]

"Ken Weitzel" wrote in message
...
Hi...

I'm not the original poster, but I've been watching
hoping that I'll find the answers I too would like
before spring...

What I want one for is to take the white glare that
every so often appears on the surface of the lake...

That'll work. Know also that a polarizing filter works most effectively
about 90 degress from the sun; i.e., form an *L* with your thumb and
forefinger (either hand, depending on which 90 degree direction you prefer)
point one at the sun, the other indicates the direction your camera should
point . Easier might be to point either shoulder at the sun and shoot
straight ahead. Obviously, the sun directly overhead is a different
problem

Shoot'em up, filtered or not, Agfa, Fuji, Kodak and all the rest will love
you for it!!

Jim

schuetzen - RKBA! wrote:
;o)-max- wrote:


Get a circular you will be on tha safe side, they work on all
cameras, don't worry, that book has made a mistake.
Which brand, either will do the job fine, there are special
effects polarizers too. ;o)-max-



buy both so that you can tell us which of these guys know what the heck he is
talking about.
fwiw and just as confused.
chas



...

Hi...

Maybe it would help all of us if I ask about this...

I have a set of Polaroid sunglasses. Maker is Polaroid,
and they're polarized. Wearing them I don't see glare on
the water, and I don't see whatever you call those glare
hot spots (water mirages) on the highway on a real hot
real bright sunny day.

If I take them off and rotate them in front of my eyes
I can watch it slowly reverse. (Instead of no glare, I
see even more glare)

Are these, then, circular?

Ken

In article , Ken Weitzel
wrote:

schuetzen - RKBA! wrote:
;o)-max- wrote:


Get a circular you will be on tha safe side, they work on all
cameras, don't worry, that book has made a mistake.
Which brand, either will do the job fine, there are special
effects polarizers too. ;o)-max-



buy both so that you can tell us which of these guys know what the heck he
is
talking about.
fwiw and just as confused.
chas



...

Hi...

Maybe it would help all of us if I ask about this...

I have a set of Polaroid sunglasses. Maker is Polaroid,
and they're polarized. Wearing them I don't see glare on
the water, and I don't see whatever you call those glare
hot spots (water mirages) on the highway on a real hot
real bright sunny day.

If I take them off and rotate them in front of my eyes
I can watch it slowly reverse. (Instead of no glare, I
see even more glare)

Are these, then, circular?

Ken


No. Circular does not refer to either the shape or the act of rotating
the filter. All polarizing filters are rotated during use to the desired
effect.

A circular polarizer is constructed differently than a linear polarizer.
The circular has a quarter wave plate sandwiched behind the polarizing
foil that allows some light to enter the lens that is circularly
polarized so it can be properly utilized by cameras that utilize a beam
splitter behind the lens to use the metering system, the auto focus
system or to properly display the finder readouts.

Both a linear and a circular polarizer use the same polarizer foil and
perform identically other then the difference in construction. Since
they perform the same purpose the circular can be used on cameras with
or without a beam splitter in the camera. A linear polarizer, however,
will not allow the metering/AF or finder displays to work properly on
those camera systems under all lighting conditions so their use is for
use on cameras without the beam splitter.

--
To reply no_ HPMarketing Corp.