UV filter vs Polarizer filter

Started May 20, 2008 | Discussions
keqwow
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UV filter vs Polarizer filter
May 20, 2008

What are the differences, and in what circumstances would you use one over the other?

Jim Boutilier
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Re: UV filter vs Polarizer filter
In reply to keqwow, May 21, 2008

While digital cameras are less sensitive to UV than film they are not immune to the effects so where you are taking pictures of distant landscapes, particularly at high altitudes, a UV filter han help eliminate the "haze" or fog caused by the UV light. Largely these filters are used for lens protection as much a anything else (easier to clean a filter or cheaper to ruin a filter by scratching or dropping than the lens itself).

A Polarizer usually reduces light by about 2 stops and helps eliminate glare off shiny surfaces like water.

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henryp
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Re: UV filter vs Polarizer filter
In reply to Jim Boutilier, May 21, 2008

Adding to Jim's comments -- it's not advisable to stack a pol filter on top of a UV or clear filter being used for lens protection. First, if you have a wide angle lens, vignetting (clipping the corners of the image) is possible. Second, each filter adds two air-to-glass surfaces to the light path. Each surface is a breeding ground for image-degrading flare, and flare is very difficult (if not impossible) to correct with Photoshop.

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Henry Posner
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GDi
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Re: UV filter vs Polarizer filter
In reply to Jim Boutilier, May 21, 2008

Jim Boutilier wrote:

While digital cameras are less sensitive to UV than film they are not
immune to the effects so where you are taking pictures of distant
landscapes, particularly at high altitudes, a UV filter han help
eliminate the "haze" or fog caused by the UV light.

Based on my experience, and on what seems to be the view of professional photographers (see luminous-landscape.com), a UV filter will not help improve the image quality on modern day lenses, because they are already anti-UV coated. They are only useful as a relatively cheap means of protecting your lens' front element, even though the necessity of protecting the durable modern coatings on lenses is questioned as well (in the source named above).

A Polarizer usually reduces light by about 2 stops and helps
eliminate glare off shiny surfaces like water.

This is true, but: a polariser eliminates glare, first and foremost. In doing so, it makes colours appear more saturated, but not in the same way as increasing the colour saturation in software would do.

Take a shiny green leaf, for example. Without the polariser, there will be a lot of reflections on the leaf's surface, which will look close to white in a photograph - hence less of the green will remain. With a polariser, the reflections are removed, and the green looks a lot greener in a photograph. A polariser only works well with a strong directional light source, ie, the sun, and works best at a 90º angle to the sun.

As a side effect, a polariser also swallows up between one and two stops of light (one stop less = half as much light, two stops = 1/4th the amount of light) depending on its angle towards the sun.

Bottom line: a polariser is a must for sunny day outdoor photography. A UV filter is all but expendable, but, I am guilty of having polarisers permanently glued to all my lenses, apart from the ultra wide angle zoom, where it has to come off occasionally, to make way - for the polariser.

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henryp
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Re: UV filter vs Polarizer filter
In reply to GDi, May 22, 2008

GDi wrote:

A Polarizer usually reduces light by about 2 stops and helps
eliminate glare off shiny surfaces like water.

This is true, but: a polariser eliminates glare, first and foremost.

A pol filter reduces reflected light. A lens hood can help reduce or eliminate flare.

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Steve Balcombe
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Re: UV filter vs Polarizer filter
In reply to henryp, May 22, 2008

henryp wrote:

GDi wrote:

A Polarizer usually reduces light by about 2 stops and helps
eliminate glare off shiny surfaces like water.

This is true, but: a polariser eliminates glare, first and foremost.

A pol filter reduces reflected light. A lens hood can help reduce or
eliminate flare.

Glare is light reflected off a subject; flare is internal reflection in the lens.

GDi's point was to clarify that the 2 stop light loss is a side effect, not the purpose of the polariser.

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tjack
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Well...
In reply to Jim Boutilier, May 23, 2008

Jim Boutilier wrote:

While digital cameras are less sensitive to UV than film they are not
immune to the effects so where you are taking pictures of distant
landscapes, particularly at high altitudes, a UV filter han help
eliminate the "haze" or fog caused by the UV light.

Clarification... This is NOT the "haze" they cut down on. In the old days of film, UV light would cause a haze on the film itself. Or, UV light would bounce off particles in the air and get recorded by the film. This had absolutely nothing to do with the actual haze in the scene. Also, the film recorded too much blue at high altitudes so a Skylight 1A or 1B was used to cut UV and some blue.

These days, film and digital sensors assemblies are not sensitive to UV light and do not create the haze as in the old days. If there is haze in the scene, there will be haze in the image. No filter can remove that. The only thing a UV filter does is to "protect" the front element of the lens in bad conditions. There is no effect on the image itself.

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Graystar
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Re: UV filter vs Polarizer filter
In reply to keqwow, May 23, 2008

A polarizer is a pretty important filter to have. I snapped the following pics as an example of what a polarizer can do for you. The two images were taken seconds apart. The difference is that a polarizer was used in the second pic.

Here are the significant points to notice in the second pic:
The sky is a deeper blue.
The clouds are better defined.
The green foliage is brighter.
The front of the houses, which are in shadows, are brighter.

When use properly a polarizer can really improve even a mundane scene as the one above, with more saturated colors and better (apparent) illumination.

A UV filter cannot do anything like this at all. UV and polarizers are two completely different animals.

Here’s a good article on how to use a polarizer.

http://www.popphoto.com/pdfs/2002/0902/Polarizer.pdf

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sherwoodpete
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Another demo shot
In reply to Graystar, May 23, 2008

Taken seconds apart. A polariser was used for both shots. The only thing that changed was the rotation of the polariser. The effect was visible through the camera viewfinder, I took the shots at positions of least glare and most glare.

(There is a slight shift in focus as the shots were hand-held and autofocus may have locked at a different point).
Regards,
Peter

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austin design
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Re: Well...
In reply to tjack, Jan 4, 2013

tjack wrote:

Jim Boutilier wrote:

While digital cameras are less sensitive to UV than film they are not
immune to the effects so where you are taking pictures of distant
landscapes, particularly at high altitudes, a UV filter han help
eliminate the "haze" or fog caused by the UV light.

Clarification... This is NOT the "haze" they cut down on. In the old days of film, UV light would cause a haze on the film itself. Or, UV light would bounce off particles in the air and get recorded by the film. This had absolutely nothing to do with the actual haze in the scene. Also, the film recorded too much blue at high altitudes so a Skylight 1A or 1B was used to cut UV and some blue.

These days, film and digital sensors assemblies are not sensitive to UV light and do not create the haze as in the old days. If there is haze in the scene, there will be haze in the image. No filter can remove that. The only thing a UV filter does is to "protect" the front element of the lens in bad conditions. There is no effect on the image itself.

Plainly not so, according to Bjorn Petersen.  Of water (vs. pollution) based haze's effects on DIGITAL cameras, he writes:

"UV affects image quality in several ways. When photographing outdoors UV light manifests itself in the form of haze, which can vary based on how close you are to large bodies of water or snow (water and snow both reflect sunlight, which in turn magnifies UV levels), altitude (the higher you go, the more UV light you encounter), and larger cities (reflective glass and metal-clad structures can also amplify ambient UV levels). This haze robs image detail, especially at longer distances with longer focal length lenses where cumulative haze densities can severely soften the sharp details of distant objects. In many respects, this neutralizes the argument against using filters for fear of compromising the resolving power of the lens, most notably telephoto lenses."

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Barrie Davis
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Re: Well...
In reply to austin design, Jan 4, 2013

austin design wrote:

tjack wrote:

Jim Boutilier wrote:

While digital cameras are less sensitive to UV than film they are not
immune to the effects so where you are taking pictures of distant
landscapes, particularly at high altitudes, a UV filter han help
eliminate the "haze" or fog caused by the UV light.

Clarification... This is NOT the "haze" they cut down on. In the old days of film, UV light would cause a haze on the film itself. Or, UV light would bounce off particles in the air and get recorded by the film. This had absolutely nothing to do with the actual haze in the scene. Also, the film recorded too much blue at high altitudes so a Skylight 1A or 1B was used to cut UV and some blue.

These days, film and digital sensors assemblies are not sensitive to UV light and do not create the haze as in the old days. If there is haze in the scene, there will be haze in the image. No filter can remove that. The only thing a UV filter does is to "protect" the front element of the lens in bad conditions. There is no effect on the image itself.

Plainly not so, according to Bjorn Petersen. Of water (vs. pollution) based haze's effects on DIGITAL cameras, he writes:

"UV affects image quality in several ways. When photographing outdoors UV light manifests itself in the form of haze, which can vary based on how close you are to large bodies of water or snow (water and snow both reflect sunlight, which in turn magnifies UV levels), altitude (the higher you go, the more UV light you encounter), and larger cities (reflective glass and metal-clad structures can also amplify ambient UV levels). This haze robs image detail, especially at longer distances with longer focal length lenses where cumulative haze densities can severely soften the sharp details of distant objects. In many respects, this neutralises the argument against using filters for fear of compromising the resolving power of the lens, most notably telephoto lenses."

Two points:-

1) Through exhaustive practical tests the effect of the UV absorbing filter has been shown to be negligible in digital cameras... to all intents and purposes a normal sensor is not sensitive to UV to any degree worth anyone concerning themselves about.... or, out another way, the filter doesn't do anything.

2) It's academic anyway. This thread died more than four years ago... (2008)

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Baz
"Ahh... But the thing is, these guys were no ORDINARY time travellers!"

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The Mad Kiwi
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Re: Well...
In reply to Barrie Davis, Jan 4, 2013

Barrie Davis wrote:

.

2) It's academic anyway. This thread died more than four years ago... (2008)

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Baz

It never dies it just keeps getting re-incarnated.

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austin design
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Re: Well...
In reply to Barrie Davis, Apr 1, 2013

Barrie Davis wrote:

austin design wrote:

tjack wrote:

Jim Boutilier wrote:

While digital cameras are less sensitive to UV than film they are not
immune to the effects so where you are taking pictures of distant
landscapes, particularly at high altitudes, a UV filter han help
eliminate the "haze" or fog caused by the UV light.

Clarification... This is NOT the "haze" they cut down on. In the old days of film, UV light would cause a haze on the film itself. Or, UV light would bounce off particles in the air and get recorded by the film. This had absolutely nothing to do with the actual haze in the scene. Also, the film recorded too much blue at high altitudes so a Skylight 1A or 1B was used to cut UV and some blue.

These days, film and digital sensors assemblies are not sensitive to UV light and do not create the haze as in the old days. If there is haze in the scene, there will be haze in the image. No filter can remove that. The only thing a UV filter does is to "protect" the front element of the lens in bad conditions. There is no effect on the image itself.

Plainly not so, according to Bjorn Petersen. Of water (vs. pollution) based haze's effects on DIGITAL cameras, he writes:

"UV affects image quality in several ways. When photographing outdoors UV light manifests itself in the form of haze, which can vary based on how close you are to large bodies of water or snow (water and snow both reflect sunlight, which in turn magnifies UV levels), altitude (the higher you go, the more UV light you encounter), and larger cities (reflective glass and metal-clad structures can also amplify ambient UV levels). This haze robs image detail, especially at longer distances with longer focal length lenses where cumulative haze densities can severely soften the sharp details of distant objects. In many respects, this neutralises the argument against using filters for fear of compromising the resolving power of the lens, most notably telephoto lenses."

Two points:-

1) Through exhaustive practical tests the effect of the UV absorbing filter has been shown to be negligible in digital cameras... to all intents and purposes a normal sensor is not sensitive to UV to any degree worth anyone concerning themselves about.... or, out another way, the filter doesn't do anything.

2) It's academic anyway. This thread died more than four years ago... (2008)

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Regards,
Baz
"Ahh... But the thing is, these guys were no ORDINARY time travellers!"

I've never understood the notion of "this thread died (X) years ago".  This is the Internet, on which people search items of interest.  Either items are relevant and useful or they aren't.  If they are, then they're free game for comment.  If they're not, what's the point of archiving them?!  Your "dead" comment is akin to saying there's no point in housing classic philosophy texts in a library because their questions are dated.  Besides, Barrie, YOU AND I HAVE JUST READ AND RESPONDED TO THIS THREAD; necessarily, then, it remains a living topic.

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