Question on Circular Polarizers

TimVermont · Mar 5, 2009

I've recently ended up with two circular polarizers, both made by Kenko. One is a vernier, marked C-PL(W). The other reads Kenko Pro1D Wide band C-PL(W). This latter one is the reason for my question. Under reflected light, it has the look of fine crepe paper under the glass, but when I look through it, does not appear to distort. The other is smooth. Is this normal, or indicative of a problem with the polarizing film?

Thanks,
Tim

glaiben · Mar 5, 2009

I thnk it's B+W that describes that crepe paper-like appearance in a circular polarizer to be an optical illusion and that no distortion is actually present. Maybe it's a function of the quarter wave polarization. I thought it was odd looking too, especially when comparing a circ to a linear polarizer. I had both - needed one - got rid of the circ.

Ed Sukach · Mar 6, 2009

glaiben,

Are you using the linear polarizer in an "autofocus" system?

Q.G. · Mar 6, 2009

Autofocus systems are not necessarily 'allergic' for linear polarizers.
So try before you buy.

Nicholas Lindan · Mar 6, 2009

Q.G. said:
Autofocus systems are not necessarily 'allergic' for linear polarizers.
So try before you buy.

And some that are, only have problems with one orientation of the polarizer.

glaiben · Mar 7, 2009

Ed Sukach said:
glaiben,

Are you using the linear polarizer in an "autofocus" system?

No - Hasselblad manual focus.

archphoto · Mar 7, 2009

So no problems now and in the future.

I would be interested if you find any diferences between them when shooting, if one is better.
I use B&W circular, like it.

Peter

Ed Sukach · Mar 8, 2009

Q.G. said:
Autofocus systems are not necessarily 'allergic' for linear polarizers.
So try before you buy.

Trying before buying might not be easy, or possible.

In reading this, my "carved-in-stone" belief that ALL autofocusing systems REQUIRE the use of a circular polarizer was shaken. So - I went to my latest acquisition, and my only autofocusing camera, a Canon EOS Elan IIe.
In scouring the Instruction book .. not one word about polarizing filters. Nada.

Then to the B&W web site and their .pdf Filter Catalog, page 15:

"B&W Circular Polarizing Filter - Highly efficient standard circular polarizing filter for all cameras with beam splitters in the light paths of their TTL exposure meters and with autofocus lenses. Circular polarizers have the same pictorial effect as linear polarization, but allow for proper exposure metering and distance settings."

The question then is whether or not the camera in question has a "beam splitter". If so, proper operation would be suspect, at least, with the use of a "linear polarizer"; while a circular polarizer would be appropriate in either case.

It might be wise to opt for the "circular", given the possibility of its use in a future system, with "beam splitter".

PhotoJim · Mar 8, 2009

Autofocus isn't the only issue. Autoexposure can be an issue too. The beam splitter is the key, as mentioned above.

cowanw · Mar 8, 2009

By auto exposure, I suppose you really mean any through the lens exposure metering , auto or manual.
My wife's new camera has the beam splitter and I put a linear polarizer on it and focused and metered in all orientations, distances and light levels.
I could not find a discrepency at all.
Than I chickened and bought her a circular filter.
But it makes me wonder if this isn't left over from earlier technology and now urban myth.

Poisson Du Jour · Mar 8, 2009

Ed Sukach said:
Trying before buying might not be easy, or possible.

In reading this, my "carved-in-stone" belief that ALL autofocusing systems REQUIRE the use of a circular polarizer was shaken. So - I went to my latest acquisition, and my only autofocusing camera, a Canon EOS Elan IIe.
In scouring the Instruction book .. not one word about polarizing filters. Nada.

Then to the B&W web site and their .pdf Filter Catalog, page 15:

"B&W Circular Polarizing Filter - Highly efficient standard circular polarizing filter for all cameras with beam splitters in the light paths of their TTL exposure meters and with autofocus lenses. Circular polarizers have the same pictorial effect as linear polarization, but allow for proper exposure metering and distance settings."

The question then is whether or not the camera in question has a "beam splitter". If so, proper operation would be suspect, at least, with the use of a "linear polarizer"; while a circular polarizer would be appropriate in either case.

It might be wise to opt for the "circular", given the possibility of its use in a future system, with "beam splitter".

B+W are in the know, ditto Hoya.
It is the meter that is going to be most affected by the type of polariser, much less the autofocus. Particularly evaluative / matrix meters. Most cameras using evaluative (Canon) or matrix (Nikon) et al systems have one or more beam splitters and thus a Circular Polariser (C-POL) is requisite.

Q.G. · Mar 8, 2009

PhotoJim said:
Autofocus isn't the only issue. Autoexposure can be an issue too. The beam splitter is the key, as mentioned above.

But also not a clear, definite key.

For instance, the OP is using a Hasselblad. Neither the Hasselblad prisms with built-in meter nor the cameras with built-in meter require a circular polarizer. And all of those 'split' part of the light away towards the metering system.

You could indeed just 'opt' to be on the safe side, and get a circular.
But those are quite a bit more expensive than regular ones, so if you do not need one ...

Poisson Du Jour · Mar 8, 2009

Q.G. said:
But also not a clear, definite key.

For instance, the OP is using a Hasselblad. Neither the Hasselblad prisms with built-in meter nor the cameras with built-in meter require a circular polarizer. And all of those 'split' part of the light away towards the metering system.

You could indeed just 'opt' to be on the safe side, and get a circular.
But those are quite a bit more expensive than regular ones, so if you do not need one ...

The expansion on the subject is relevant anyway for those reading and wondering why there are two distinct versions of polarizer and obviously, higher prices for the circular. Yes, I am aware the OP's mentioned Hasselblad is not so endowed with the techie evaluative/matrix stuff the rest of us are using. I imagine the cost for a Hassy POL would be quite substantial.

Q.G. · Mar 9, 2009

Poisson Du Jour said:
Yes, I am aware the OP's mentioned Hasselblad is not so endowed with the techie evaluative/matrix stuff the rest of us are using.

You're focussing on the wrong bit.
The important bit is that they use beam splitters anyway.

TimVermont · Mar 9, 2009

"For instance, the OP is using a Hasselblad. "

No, the OP asked about the fine crepe-paper like appearance of one circular polarizer versus another of the same manufacture.

benjiboy · Mar 9, 2009

I just looked in the latest Hasselblad Manual, it says all the V system cameras use regular linear polarizers.

Q.G. · Mar 9, 2009

TimVermont said:
"For instance, the OP is using a Hasselblad. "

No, the OP asked about the fine crepe-paper like appearance of one circular polarizer versus another of the same manufacture.

Apologies, it was Glaiben.

As the Fish Plate of the Day mentioned "The expansion on the subject is relevant anyway for those reading and wondering why there are two distinct versions of polarizer".

Ralph Javins · Mar 9, 2009

Q.G. said:
As the Fish Plate of the Day mentioned "The expansion on the subject is relevant anyway for those reading and wondering why there are two distinct versions of polarizer".

Good morning;

The additional discussion of the differences in the two types of polarizing filters commonly available certainly is appropriate. The differences in the two types really become noticeable when you are comparing the prices for a 112 mm or a 122 mm polarizing filter.

Oh, why did I want that big lens anyway? Bigger filters, a Wimberley gimbal head, a bigger tripod, . . . . .

Poisson Du Jour · Mar 9, 2009

Ralph Javins said:
Good morning;

The additional discussion of the differences in the two types of polarizing filters commonly available certainly is appropriate. The differences in the two types really become noticeable when you are comparing the prices for a 112 mm or a 122 mm polarizing filter.

Oh, why did I want that big lens anyway? Bigger filters, a Wimberley gimbal head, a bigger tripod, . . . . .

Sympathies.
I imagine a 112 or 122mm C-POL would cost a king's random indeed, moreso if it's a Kaisseman (i.e. B+W's venerated objet de art). I have always been much aggrieved at the high cost of smaller by comparison C-POL filters ie. going from 67mm to 77mm incurred a $39 increase! Fortunately, only once bitten: step-up/down rings are used to good effect now.

Question on Circular Polarizers

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