Cars, Outdoors and Circular Polarizers

mercphoto

I've been struggling lately with when to use, and when not to use, a circular polarizer for static outdoor automotive shots. I certainly see their benefits and the profound effect it can have, but I'm struggling with the trade-offs of using them, especially for three-quarter views. Sometimes it feels like in order to get a nice looking windshield or hood I end up with horrible reflections in the side. Or to get rid of side reflections I then loose all detail in the subtle curves of the sheet metal. More than few times I've liked the non-CP shots better than CP shots. And on many occasions I've ripped off several identical shots where all did was rotate the CP a touch each time and decide later which looks better. I have yet to try stacking two shots done with different orientations but I hope to soon.

I'm wondering if this is normal, or if this is a sign that I need to pay better attention to setup details. Such as the exact orientation of the car to the sun, or to its surroundings (and hence the source of reflections). Or if shooting twice with different polarization and stacking is a reasonable alternative.

I can foretell two possible types of answers. One being "the best approach that may take hours to accomplish is..." to "the best quick compromise to a bad situation would be...". Thanks in advance for either type of advice. Please note that some of the more obvious answers, like shoot with the sun to your back, are not always possible. Sometimes geography just gets in your way. You want the car with a certain object as a background, and no matter what time of day or day of year that sun is always going to be at a side-angle to the car rather than behind you.

ziggy53

mercphoto wrote:

... I'm wondering if this is normal...

Sounds normal to my experience. Sometimes polarizers are a blessing, sometimes no help at all.

It's nice to have options but I haven't found any total solutions that didn't involve a lot of planning and setup.

mercphoto

ziggy53 wrote:

Sounds normal to my experience. Sometimes polarizers are a blessing, sometimes no help at all.

It's nice to have options but I haven't found any total solutions that didn't involve a lot of planning and setup.

Thanks! Was kinda what I was fearing the answer would be.

jfriend

mercphoto wrote:

I've been struggling lately with when to use, and when not to use, a circular polarizer for static outdoor automotive shots. I certainly see their benefits and the profound effect it can have, but I'm struggling with the trade-offs of using them, especially for three-quarter views. Sometimes it feels like in order to get a nice looking windshield or hood I end up with horrible reflections in the side. Or to get rid of side reflections I then loose all detail in the subtle curves of the sheet metal. More than few times I've liked the non-CP shots better than CP shots. And on many occasions I've ripped off several identical shots where all did was rotate the CP a touch each time and decide later which looks better. I have yet to try stacking two shots done with different orientations but I hope to soon.

I'm wondering if this is normal, or if this is a sign that I need to pay better attention to setup details. Such as the exact orientation of the car to the sun, or to its surroundings (and hence the source of reflections). Or if shooting twice with different polarization and stacking is a reasonable alternative.

I can foretell two possible types of answers. One being "the best approach that may take hours to accomplish is..." to "the best quick compromise to a bad situation would be...". Thanks in advance for either type of advice. Please note that some of the more obvious answers, like shoot with the sun to your back, are not always possible. Sometimes geography just gets in your way. You want the car with a certain object as a background, and no matter what time of day or day of year that sun is always going to be at a side-angle to the car rather than behind you.

If you can show us some example photos, we might be able to offer a little more concrete advice. Circular polarizers work by eliminating all light that is polarized in the direction that lines up with the orientation of the circular polarizer and some of the light that is close to that orientation, but not right on. Regular sunlight is randomly polarized such that a circular polarizer eliminates about half of it no matter how it's oriented. But, when randomly polarized light is reflected off a surface, it may acquire a polarization bias such that most or all of the light rays have a particular polarization orientation. See this link for a simple explanation of how reflection causes light to get linearly polarized. This is typically called polarized light and this is obviously when you see dramatic differences depending upon how you orient the circular polarizer. Depending upon what you want to achieve, you can either block polarized light or you can enhance polarized light (by blocking some of the randomly polarized light elsewhere in the scene, but not much of the polarized light).

The classic landscape examples of these two uses are:

1. Make the sky much bluer by blocking polarized light coming from the sky (sunlight reflected off particles in the sky).
2. Make a landscape reflection off of water appear brighter by turning the CP so that none of the reflection is blocked, but 1/2 the randomly polarized light from elsewhere in the scene is blocked.

I say all this as background for understanding what is going on in your car shots. If you are simulateously trying to block reflections from the glass in the car and enhance reflections from the metal on the car, you will only be able to do it with one shot if all the two are somehow polarized at 90 degrees from one another. If they aren't, then minimizing one will minimize the other too and the only way to get what you really want is to combine two shots with different orientations of the CP.

tsk1979

Circular polarizer will help only in some situations, but overall its a blessing at car show.
Look at my auto expo gallery
http://tanveer.smugmug.com/gallery/4196468