Angle of Incidense Applications in Portraiture - Page 2
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Old 09-22-2014   #11
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Default Re: Angle of Incidense Applications in Portraiture

Or you can learn a lot even without a camera if you just pick up a cheap polarizing filter with the plane of polarization marked on it as I did when I was a kid. It doesn't even have to be a circular polarizer. You can even use a pair of cheap polarizing sunglasses, where the plane of polarization is vertical if worn normally without tilting them; but you probably already have a polarizer in you are seriously into landscape or product photography. If you haven't tried this experiment before, you are in for some surprises, such as the polka dot or checkerboard pattern when I first tried to kill the reflection from the tempered rear window of a car. Looking at most LCD monitors will also come as a surprise, which can be explained when you know that such monitors have polarizing filters of their own that are necessary for their proper operation.

By the way, if you orient your polarizer for minimum glare attenuation, you can actually enhance the glare reflections by up to a full stop compared to the same scene without a polarizer. Unpolarized light passing through a polarizer will be attenuated by half, plus the polarizer's basic attenuation. If the exposure is compensated to allow for this amount of attenuation, then light polarized in the direction the filter is oriented will be attenuated only by the polarizer's basic attenuation and will not suffer the further attenuation by half as unpolarized light would be. The basic effect will then be to enhance the brightness of the polarized reflection by one stop compared to the unpolarized light. (To attenuate the polarized light by the same amount as unpolarized light, the polarizer must be oriented at an angle of 45 degrees to the incoming polarized light.)

I haven't seen any discussion of the phenomenon, but it is possible to kill most of the reflection from a bald person's head with a polarizer, if the angle of incidence is right. If full attenuation is too much, there is no law that says you must orient the polarizer for maximum glare attenuation; you can deliberately misalign the polarizer slightly if you still want a little glare to show texture. I think that Ed has already mentioned something about this effect when talking about using polarizers in product shots.
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Old 09-24-2014   #12
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Default Re: Angle of Incidense Applications in Portraiture

Enjoyed the read. Ed - one suggestion about your circular diagram you may want to consider in order for it to appeal to as many people as possible. You could refer to the circle as a clock face. So that the split lighting would be called 3 o'clock instead of 90 degrees. Many times the catch lights in the eyes are already referred to as something like 11 o'clock or 1 o'clock. Just a thought.
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Old 09-24-2014   #13
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Default Re: Angle of Incidense Applications in Portraiture

Very interesting stuff Ed, Duck and Scoundrel. Thanks for your extensive contributions to my understanding of this interesting topic.
That is a good idea about using a clock analogy Chick.
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Old 09-24-2014   #14
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Default Re: Angle of Incidense Applications in Portraiture

Great job guys......clockface as relates to to person face not camera will be helpful


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