Circular or linear polarizer? at DVinfo.net

Doug Boze · November 20th, 2005, 12:39 AM

It amazes me that after umpteen years I've not tested this but... since I've always had SLR's with off-the-film metering (Pentax LX hammer, doubles as a camera) and thus have always used circular polarizers for exposure's sake, does it make any difference on 3-CCD camcorders? I've only bought CPs because of this (safer then sorrier).

I know a prism or mirror of sorts splits the colors appropriately, but could a linear polarizer have any effect? Next spring, Zotz notwithstanding, I intend to get an XL-2, as well as move to a 4x4 filter system. Taking notes, now, of course. Autofocus, unless strides have been made in this area commensurate with other aspects of video, is of little importance. Nevertheless, there could be times when it might be used, so I shouldn't have to worry about filtration bonking it. Ultimately, I'll not be penny-wise and pound-foolish, yet there's that side of me that fairly cries out for a reasonable savings.

So, LP or CP with 3 CCDs?

Robert J. Wolff · November 20th, 2005, 08:55 AM

Good Morning, Doug.

Most manufacturers recommend the Circular. I have used both. I can not say that I personally observed any difference. But, when using a linear filter, I can see where under tough lighting conditions, that the image passing through the filter, could be deteriorated before it is on the media.

Why take a chance?

Charles Papert · November 20th, 2005, 12:12 PM

This is a matter of long debate (try doing a search under "circular polarizer" and you'll see the results). Robert, is it that the manufacturers recommend circular polas or the sellers? If manufacturers, where are they listing those recommendations? I have long believed that the sellers have promoted them because they cost more. The filter manufacturers do not specifically spec them for video cameras.

Personally, I have always used linear polas for video and never experienced any problems.

Robert Ballew · November 23rd, 2005, 07:54 AM

Charles, you are correct regarding sellers pushing the circular polarizers, and there are as many opinions on this as there are people to ask. We did a rather lengthy test when we first went digital in '99. Linear polarizers worked fine, so did the circular. Only difference? Circular was adjustable, linear wasn't. I like the adjustability of the circular so that's what I use. But, we still have the linear ones around here somewhere.

Robert

Charles Papert · November 23rd, 2005, 09:20 AM

Robert, by "adjustable" you mean...?

Obviously both types are "activated" by being rotated to dial in the degree of polarization, not sure what other adjustment there is to a Pola.

Robert Ballew · November 23rd, 2005, 09:51 AM

Charles, Yes, my post made very little sense. I apologize-I was interrupted in the middle of writing it. Lost my train of thought. Let's try again and, if my understandig of this subject has been wrong all along please advise.

On our first digicams I had no way of knowing if the optics had polarization employed internally. If so, the linear would possibly have caused too much absorbtion, at least in some cases. The circular would alleviate the issue, if internal polarization was used in the optics, and I never had to worry about it again.
I do not take claim for figuring this out. This stuff came from a Tiffen tech guy that I talked to. As I recall, he felt the whole issue was probably directed more at the digital still cameras, not so much video.

I hope that makes more sense.

Robert

Alex Horvath · November 23rd, 2005, 10:58 AM

To my knowledge linear polfilter doesn´t work properly with autofocus, circular does.
anyway, polfilters are not run´n gun, adjusting the pol and manual focus, it´s a non issue

alex

Robert Ballew · November 23rd, 2005, 12:03 PM

Alex, your post jogged my memory a bit. I think I might, maybe, recall that was the issue when the Tiffen guy said it was more an issue with still cameras as opposed to the video cams. I do not remember if we tested that. Probably not as we rarely do run 'n gun shooting so, you're right....non issue.

Robert

Christopher Lefchik · December 9th, 2005, 09:03 AM

Here's some information on linear vs. circular polarizers from Popular Photography:

"A linear polarizer filters diffused light in unidirectional lines, and can work with most cameras. A circular polarizer consists of a standard linear polarizer plus a quarter-wave retarder that scrambles polarized light so it moves in a spiral or circular direction. A circular polarizer is needed when using many modern SLRs to prevent interference with their polarized autofocusing and autoexposure systems." (Help! - October 2003)

"A circular polarizer works with any camera, whether its metering system incorporates a semi-silvered mirror (in effect, a polarizer) in its light path or not. So if you have a circular polarizer that fits your lenses, you don’t need to buy a linear polarizer. However, it doesn’t work the other way around—if you use a linear polarizer on a camera requiring a circular polarizer, your exposure system may perform erratically." (Tech Support 07/04)

"Virtually any camera with an autofocus system, and many cameras with TTL-metering systems, require a circular polarizer. Using a linear polarizer can result in focusing and exposure errors." (4 Filters Every Photographer Must Own)

November 20th, 2005, 12:39 AM	#1
Doug Boze Major Player Join Date: Jun 2005 Location: Auburn, Washington Posts: 218	Circular or linear polarizer? It amazes me that after umpteen years I've not tested this but... since I've always had SLR's with off-the-film metering (Pentax LX hammer, doubles as a camera) and thus have always used circular polarizers for exposure's sake, does it make any difference on 3-CCD camcorders? I've only bought CPs because of this (safer then sorrier). I know a prism or mirror of sorts splits the colors appropriately, but could a linear polarizer have any effect? Next spring, Zotz notwithstanding, I intend to get an XL-2, as well as move to a 4x4 filter system. Taking notes, now, of course. Autofocus, unless strides have been made in this area commensurate with other aspects of video, is of little importance. Nevertheless, there could be times when it might be used, so I shouldn't have to worry about filtration bonking it. Ultimately, I'll not be penny-wise and pound-foolish, yet there's that side of me that fairly cries out for a reasonable savings. So, LP or CP with 3 CCDs? __________________ "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -- Benjamin Franklin, 1759

November 20th, 2005, 08:55 AM	#2
Robert J. Wolff Major Player Join Date: Sep 2001 Location: Adirondacks of New York Posts: 210	Good Morning, Doug. Most manufacturers recommend the Circular. I have used both. I can not say that I personally observed any difference. But, when using a linear filter, I can see where under tough lighting conditions, that the image passing through the filter, could be deteriorated before it is on the media. Why take a chance? __________________ Himself

November 20th, 2005, 12:12 PM	#3
Charles Papert Wrangler Join Date: Jan 2002 Location: Los Angeles, CA Posts: 6,810	This is a matter of long debate (try doing a search under "circular polarizer" and you'll see the results). Robert, is it that the manufacturers recommend circular polas or the sellers? If manufacturers, where are they listing those recommendations? I have long believed that the sellers have promoted them because they cost more. The filter manufacturers do not specifically spec them for video cameras. Personally, I have always used linear polas for video and never experienced any problems. __________________ Charles Papert www.charlespapert.com

November 23rd, 2005, 09:20 AM	#5
Charles Papert Wrangler Join Date: Jan 2002 Location: Los Angeles, CA Posts: 6,810	Robert, by "adjustable" you mean...? Obviously both types are "activated" by being rotated to dial in the degree of polarization, not sure what other adjustment there is to a Pola. __________________ Charles Papert www.charlespapert.com

November 23rd, 2005, 07:54 AM	#4
Robert Ballew Regular Crew Join Date: Jul 2005 Location: Houston, Texas Posts: 29	Charles, you are correct regarding sellers pushing the circular polarizers, and there are as many opinions on this as there are people to ask. We did a rather lengthy test when we first went digital in '99. Linear polarizers worked fine, so did the circular. Only difference? Circular was adjustable, linear wasn't. I like the adjustability of the circular so that's what I use. But, we still have the linear ones around here somewhere. Robert

November 23rd, 2005, 09:51 AM	#6
Robert Ballew Regular Crew Join Date: Jul 2005 Location: Houston, Texas Posts: 29	Charles, Yes, my post made very little sense. I apologize-I was interrupted in the middle of writing it. Lost my train of thought. Let's try again and, if my understandig of this subject has been wrong all along please advise. On our first digicams I had no way of knowing if the optics had polarization employed internally. If so, the linear would possibly have caused too much absorbtion, at least in some cases. The circular would alleviate the issue, if internal polarization was used in the optics, and I never had to worry about it again. I do not take claim for figuring this out. This stuff came from a Tiffen tech guy that I talked to. As I recall, he felt the whole issue was probably directed more at the digital still cameras, not so much video. I hope that makes more sense. Robert

November 23rd, 2005, 10:58 AM	#7
Alex Horvath Regular Crew Join Date: Nov 2005 Location: Innsbruck,Austria Posts: 45	To my knowledge linear polfilter doesn´t work properly with autofocus, circular does. anyway, polfilters are not run´n gun, adjusting the pol and manual focus, it´s a non issue alex

November 23rd, 2005, 12:03 PM	#8
Robert Ballew Regular Crew Join Date: Jul 2005 Location: Houston, Texas Posts: 29	Alex, your post jogged my memory a bit. I think I might, maybe, recall that was the issue when the Tiffen guy said it was more an issue with still cameras as opposed to the video cams. I do not remember if we tested that. Probably not as we rarely do run 'n gun shooting so, you're right....non issue. Robert

December 9th, 2005, 09:03 AM	#9
Christopher Lefchik Trustee Join Date: Jul 2003 Location: US Posts: 1,152	Here's some information on linear vs. circular polarizers from Popular Photography: "A linear polarizer filters diffused light in unidirectional lines, and can work with most cameras. A circular polarizer consists of a standard linear polarizer plus a quarter-wave retarder that scrambles polarized light so it moves in a spiral or circular direction. A circular polarizer is needed when using many modern SLRs to prevent interference with their polarized autofocusing and autoexposure systems." (Help! - October 2003) "A circular polarizer works with any camera, whether its metering system incorporates a semi-silvered mirror (in effect, a polarizer) in its light path or not. So if you have a circular polarizer that fits your lenses, you don’t need to buy a linear polarizer. However, it doesn’t work the other way around—if you use a linear polarizer on a camera requiring a circular polarizer, your exposure system may perform erratically." (Tech Support 07/04) "Virtually any camera with an autofocus system, and many cameras with TTL-metering systems, require a circular polarizer. Using a linear polarizer can result in focusing and exposure errors." (4 Filters Every Photographer Must Own)