circular polarizer filter

[granitespider]

Would a circular polarizer filter have helped reduce the reflections picked up on the surface of this car... particularly where it shows up heavy in the fender?

 

[plugin]

Polarizers do not help for reflections off metallic surfaces, so it is possible (if the paint contains metal flakes) that it would not get rid of the reflections. You would have to try to be certain. Experimenting with my car shows some angles work better than others.

 

[Maverick07]

The polarizing filter does not well on metal surfaces. I normally bracket my exposures and in post processing eliminate the glare. You may also want to try a graduated ND; however, these are a little pricey. The CP filter is an invaluable tool for shooting outdoors.

HTH

 

[joe filer]

In your image, there is a wide range of angles of reflected light. A polarizer would help with part, but not a lot of the reflections.

In my experience a polarizing filter will work with reflections off any type of surface: metal, glass, water, tree leaves, etc. The greatest effect is on light reflected off a smooth flat surface (glass or water). The major factor is the angle at which the source light is being reflected from the surface. The light is polarized more at steeper angles, so the filter blocks more of the reflection. A direct reflection, such as flash back from camera flashed directly into a mirror, has no polarized rays, so the filter would have no effect.

The same is true with using the polarizer on clear blue sky. The most polarizing occurs in an arc at a 90° angle to the sun. The effect decreases at you move toward 0 or 180°

Circular polarizers are higher priced and have little advantage over the linear polarizing filters. I have both styles and stack them in pairs for variable neutral density (the top one has to be linear). I decided that the circular style was an unnecessary expense since either type works well alone on my dslrs. I have never seen any adverse affects on auto focus, metering or other issues by using my linear polarizer.

--
My 2¢ worth
Joe Filer
Mahomet, IL
http://www.pbase.com/filer
My latest hobby: http://www.pbase.com/filer/longarmquilting

My 60 year still camera history: http://www.pbase.com/filer/image/49099880/original

My wife is proud to participate in the Alzheimer's Quilt Initiative!
http://www.alzquilts.org/

She has met her first $1000 promise for Alzheimer's research and is working on her second $1000. Cheer her on at: http://www.amisimms.com/1000promise.html

 

[plugin]

Polarizers actually do absolutely nothing for reflections off metallic surfaces. And circular polarizers are a very good idea for DSLRs. A linear polarizer may seem to work without issues, but can affect metering and/or focus at some angles. Just because you have not noticed it does not mean it does not happen, so giving people advice based on misinformation is not a good idea.

In your image, there is a wide range of angles of reflected light. A polarizer would help with part, but not a lot of the reflections.

In my experience a polarizing filter will work with reflections off any type of surface: metal, glass, water, tree leaves, etc. The greatest effect is on light reflected off a smooth flat surface (glass or water). The major factor is the angle at which the source light is being reflected from the surface. The light is polarized more at steeper angles, so the filter blocks more of the reflection. A direct reflection, such as flash back from camera flashed directly into a mirror, has no polarized rays, so the filter would have no effect.

The same is true with using the polarizer on clear blue sky. The most polarizing occurs in an arc at a 90° angle to the sun. The effect decreases at you move toward 0 or 180°

Circular polarizers are higher priced and have little advantage over the linear polarizing filters. I have both styles and stack them in pairs for variable neutral density (the top one has to be linear). I decided that the circular style was an unnecessary expense since either type works well alone on my dslrs. I have never seen any adverse affects on auto focus, metering or other issues by using my linear polarizer.

--
My 2¢ worth
Joe Filer
Mahomet, IL
http://www.pbase.com/filer
My latest hobby: http://www.pbase.com/filer/longarmquilting

My 60 year still camera history: http://www.pbase.com/filer/image/49099880/original

My wife is proud to participate in the Alzheimer's Quilt Initiative!
http://www.alzquilts.org/

She has met her first $1000 promise for Alzheimer's research and is working on her second $1000. Cheer her on at: http://www.amisimms.com/1000promise.html

 

[granitespider]

That's cool. I'll take the experiences of everyone for sure but I guess the best way to know what will and won't work is to test it out. I do have a CPL for my 50mm but didn't have it with me. I was quite frustrated in that from any angle this guys car was reflecting back all kinds of stuff. Not a clean location which is why I suppose good car shots aren't done in a busy parking lot in front of a strip of stores. I just happened to see this guy cruising down the street and turned around to follow him to his stop.

 

[Maverick07]

Learn fromthe mistakes we make. Digital shots are very inexpensive. If you are not shooting RAW may want to ask why. Shoot muliple shots on a tripod will pay off exponentially. Three pieces of equipment in addition to your basic gear for any beginning photgrapher. Tripod (Carbon fiber preffered), Circuliar Polarizing Filter, Lens hood.

Tripod investing in a carbon fibre will pay back many times over. The disadvantage of the carbon fibre is you have lost some leverage if you encounter some individuals with bad intentions.

Circuliar polarizing filter: Reduces glare and enriches saturation.

Lens Hood: Would not go without one. Besides reducing flare, protects the optics. The number of times I have banged my lens hood rather then optics has payed a hundred times over.

 

[joe filer]

I admit that I am not a physicist, but I do consider myself to be well educated and have 60 years of photographic experience. I continually try to learn by experimentation and like to share any gained knowledge with others.

I took a short series of comparison photos today. They were hand held using auto exposure and a Linear Polarizer. I am well aware that using a polarizing filter decreases the brightness caused by glare. This, in turn, causes the camera to compensate by increasing the overall auto exposure. However, I think that the results are good enough to illustrate my point.

The wind was blowing briskly while photographing the leaves, so there is some motion blur.

Metal objects, whether painted or unfinished, are usually comprised of complex curves and shapes which limit the "flat" areas needed for obvious polarized light reflections. Small polarized reflections are still present, just not as obvious. Another limiting factor with metal is that most objects have a micro texture from machining or casting which also limits the truly flat areas for polarized reflections. Again, there are still small areas of polarized light that can be filtered.

The first set of images is of a painted metal car finish, similar to the OP question. The glare on the handle is obviously reduced in the polarized image. Polarizing filters can be effective when photographing automobiles.

Thefoliageefoliage folaige. These leaves weren't very glossy, so the effect is minimal but still present.

The last set is of a stainless steel knife blade. Stainless steel IS metal. Where the blade is at the necessary reflection angle, the polarized image is definitely darker and, if you look closely, the reflections on the curved metal "hilt" are softer in the polarized image. Just because an object doesn't have extensive flat surfaces doesn't mean that a polarizing fiter won't work.



--
My 2¢ worth
Joe Filer
Mahomet, IL
http://www.pbase.com/filer
My latest hobby: http://www.pbase.com/filer/longarmquilting

My 60 year still camera history: http://www.pbase.com/filer/image/49099880/original

My wife is proud to participate in the Alzheimer's Quilt Initiative!
http://www.alzquilts.org/

She has met her first $1000 promise for Alzheimer's research and is working on her second $1000. Cheer her on at: http://www.amisimms.com/1000promise.html

 

[plugin]

It is nothing to do with flat or not. Painted metal is not really a metallic surface (except some paint contains metal flakes of various sizes to create a pearl or sparkly appearance. But the physics of polarizers is such that they do not affect reflections off metallic surfaces - period. This is true whether flat or not. Linear polarizers and Circular polarizers are the same in this regard. \Your first two pictures are self evident, and have nothing to do with anything I said. The third is meaningless because the angle of the camera and knife are not identical, so whether one is darker or not is more to do with that than the polarizer.

If you don't believe me, look at the reflection in a conventional (silvered glass) mirror. The reflection remains no matter what angle you look at it through a polarizer. There will be secondary reflections off the front glass surface, which will be affected by the filter, but the reflection off the silver surface will not.

 

[ThrillaMozilla]

It is nothing to do with flat or not. Painted metal is not really a metallic surface (except some paint contains metal flakes of various sizes to create a pearl or sparkly appearance. But the physics of polarizers is such that they do not affect reflections off metallic surfaces - period. This is true whether flat or not. Linear polarizers and Circular polarizers are the same in this regard. \Your first two pictures are self evident, and have nothing to do with anything I said. The third is meaningless because the angle of the camera and knife are not identical, so whether one is darker or not is more to do with that than the polarizer.

If you don't believe me, look at the reflection in a conventional (silvered glass) mirror. The reflection remains no matter what angle you look at it through a polarizer. There will be secondary reflections off the front glass surface, which will be affected by the filter, but the reflection off the silver surface will not.

This is correct, but this demonstration could still go a little bit astray if the light that is incident on the mirror is polarized. So no one should be surprised if you notice a small effect.

A metallic surface will not polarize light, but it will reflect polarized light. You can prove that by holding a circular polarizing filter to a mirror. Try it first with the subject side to the mirror, and then with the camera side to the mirror. Explaining this without resort to magic is an exercise for people who really want to understand the subject.

This is written mostly for other people. I'm sure plugin knows this.