Polarizers

[Skylab001]

Which kind should I use on my beaulieu 6008, Linear or circular? From photo's I've seen it looks like the Linear gives better color saturation....but from what people have been telling me Circular is better. But these are all people shooting Stills on new cameras.

[Lunar07]

Which kind should I use on my beaulieu 6008, Linear or circular? From photo's I've seen it looks like the Linear gives better color saturation....but from what people have been telling me Circular is better. But these are all people shooting Stills on new cameras.

Use Linear. The people you are refering to are shooting stills on digital cameras most probably.

[christoph]

Use Linear. The people you are refering to are shooting stills on digital cameras most probably.

in fact, linear pol filters are known to confuse modern TTL (through the lens) lightmeters.. this does *not* only apply to digital cameras but also to normal SLRs... i'm not sure how sensitive the 6008s meter is to linear or circular meters, but if in doubt use a circular one.. colors should be the same, it's just that circulars are more expensive.

++ christoph ++

[Lunar07]

Use Linear. The people you are refering to are shooting stills on digital cameras most probably.

in fact, linear pol filters are known to confuse modern TTL (through the lens) lightmeters.. this does *not* only apply to digital cameras but also to normal SLRs... i'm not sure how sensitive the 6008s meter is to linear or circular meters, but if in doubt use a circular one.. colors should be the same, it's just that circulars are more expensive.

++ christoph ++

I have never had a problem with a linear polarizer on any of my cameras. And I have always been advised to use circular ones on digital cameras only.

[aj]

On 35mm SLR cameras the autofocus may get in trouble if light is polarized. The autofocus gets its image through a half mirror which uses a polarizing technique. Under circumstances this may get dark...

The 6008 has also a beamsplitter for the lightmeter to take some light out off the viewfinder image. I don not know how this works. Probably best tested while rotating the polarizer and watching the lightlevel. Should fluctuate a bit but not get very low.

[Petteri]

My Bauers lightmeters atleast where totaly cofused with Linear. Then i bought Circular and since that i'v been happy ;-)

I would say buy Circular or prepare your self with external light meter!

Petteri

[monobath]

Circular polarizers work on all cameras. Linear polarizers work on cameras that don't use beam splitters for metering purposes, such as semi-silvered mirrors that allow a proportion of light through to a sensor behind the mirror, or autofocus systems. Generally speaking, anyway. There are some exceptions. If in doubt, use a circular polarizer.

Note 28.4 on this page has some good info on the differences between linear and circular polarizers Photo Forum FAQ

[S8 Booster]

Never had a problem with linear polarisers on my Canon 1014 XL-S but it need to be properly aligned vs the beamsplitter to get suitable readings.

Possibly a -1/3 or -2/3 exposure setting may be tested in addition on my cam - you may check this out on yours.

Circular filters do not give any good results (if any - it is in the technology) on my cam. I´d rather not use it at all just stick to the original lenz coating not spotting a significant difference.

Some info: http://www.thkphoto.com/products/hoya/gf-04.html

Light rays which are reflected by any surface become polarised and polarising filters are used to select which light rays enter your camara lens. PL (Linear Polarising) and PL-CIR (Circular Polarising) filters have the same effect, but it is important that you choose the correct version for your camera. They allow you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. They also enable colors to become more saturated and appear clearer, with better contrast. This effect is often used to increase the contrast and saturation in blue skies and white clouds. HOYA's polarising filters do not affect the overall color balance of a shot.



How to select the correct Polarising filter:
Many of today's cameras use semi-silvered mirrors or prisms to split the light entering the viewfinder in order to calculate exposure and focusing distance. PL (Linear Polarising) filters can sometimes interact with these items to give unpredictable exposure or focusing. So we recommend that you choose a PL-CIR filter unless you have a manual focus camera which has no beam splitter.

Some old post:

http://www.kelvin.net/Hasselblad/hasselbladV1n1685.txt

You have to scroll down the page to find this:

Why's the circular polarizer the way to go? If you're using it on a
Hasselblad it doesn't make any difference what type of polarizer you get.
-- Unless the 205 uses some semi-transparent mirror for the spot meter.
Linear (top) polarizers are more effective than their circular counterparts so you get a more pronounced effect of the polarization. This effect is obviously adjustable by turning the filter ring.

You will need a circular polarizer in the following situations:
1) If you're using auto focus.
2) If the metering system in your camera requires it (typically only spot
meters require circ. pol., CW and partial meters are fine with the lin. pol.)

Some more about CIR vs POL;

http://www.pechorin.com/messages/95552.html

Scroll to find:

Re: Circular True-Pol Polarizing OR True-Pol Polarizer- beaser - 25th Sep 2002 8:04
You'll have to retype your reply, I don't fully understand it.
I've been through this particular escapade before and I get angry with the lemming philosphy. I get the "safe" answers every day on a multitude of topics. I'm a tech and it's my job to solve problems and to sweep away the BS. The safe answers usually cost people a lot of money. No picture on your TV? We'll just change all the parts , just to be sure.
I had actually called tiffin and asked a tech support type the question. The answer was use circular. I asked to speak to someone senior. I asked why I had gotten that answer when the following is posted on the Tiffen site under polarizers
http://www.tiffen.com/ultrapol.htm
Some camera-related optics,like a video tap, employ a
partially silvered mirror, or beamsplitter. This may require the use of a Circular UltraPol, which places a clear, quarter-wave retarder on the camera side of the filter,effectively de-polarizing the light being recorded, after the image enhancement is done. Circular UltraPol filters are suitable for virtually all situations; Linear
UltraPol filters excel in traditional applications.
Since canon or Sony don't use a video tap or a beamsplitter the boss man figured it was OK. I asked him why they recomended the circular and the answer was it was easier to just recomend it accross the board in case you wanted to use your polarizer on yoyr SLR too. I personally consider that a technical cop out.
Instead of arguing, buy one and try it, it's half the price. I use a linear on both my cams and I'm a bloody purist. I won't own crap.
Try it, you can't loose. If it doesn't work , not only will I kiss your butt but I'll give you an hour to draw a crowd. You can return it and pay the extra and still have your circular.
Note: most of the people on the help desks shouldn't be there. They're reading safe answers out of a book.
Read more | Reply...

R

[S8 Booster]

Another old post:

Hi Barry.

It should be something like this: I basically do not understand why CIR polarizer are made other than for digital cameras from the info I collected on this earlier on.

Also from the info it is apparent that the linear polarizer will give better effect. The linear pol seems to simply lineraise/filter the light while the CIR "corkscrews" the light messes about a littlle forth and back and then lineraises it again in a way.

I have both and have a firm impression that the LIN gives better effect as tells other posters on other boards I have seen comment on this.

The CIR will improve the colours as well. I suggest you shoot some comparasion shots.

Check out this for difference between the LIN / POL: http://www.phy.duke.edu/~geng/polarizer.html

Two ways to distinguish a linear polarizer and a circular polarizer:
- Look at (non-metallic) reflective surface through the polarizer and flip it around. A circular won't kill reflections in reversed position, a linear will still work.

- Look through the polarizer into the mirror, and flip it around. A linear won't change density/transmission, a circular will black out in one of the positions (See below for a detailed explaination).


Circular Polarizers



A circular polarizer converts unpolarized light to circularly polarized light. Circular polarizers are composite structures consisting of a linear polarizer and a quarter wave retarder. The retarder axis is oriented at 45 degrees with respect to the polarizer axis. As incident light passes through the composite it is converted to circularly polarized light. After reflection the light returns, passing through the retarder a second time. The net result is that the plane of polarization is rotated 90 degrees with respect to the original orientation. The linear polarizer then blocks the return light. This eliminates reflections. (See top diagram) On the other hand, light originating from behind the circular polarizer passes through it only one time and is not blocked. If a display is placed behind a circular polarizer, reflections from the surface of the display are eliminated but characters on the display are seen clearly. In fact, their contrast is enhanced.

Light passes through a circular polarizer, is reflected by a mirror, and is blocked on its return path.

Usually, the circular polarizers are constructed with quarter wave retarders for 550 nm, the center of the visible region.

R

[Petteri]

In my test i have got better results to reduse reflections with Circular

That could ofcourse be quality of filter issue!

Petteri