First, I do not own a T-10, let alone a polarizer for such. I do have a
lester dine ringflash and I did ask the question last year whether the
polarizer was circular or not, thinking that maybe I could home brew such a
filter for my flash. I digress.
My unscientific method was to take two polarizers and while holding one such
that it was in the path of the light source causing a point of glare on a
metal paperweight, I held the second polarizer in my viewing path. I then
rotated the "source" polarizer until the glare was maximum. By rotating the
filter in my viewing path 90 degrees (either way) I could eliminate the
glare. Rotate the source filter some, rotate the viewing filer same amount,
glare gone. A single polarizer by itself would not eliminate the glare.
I tried this with both circular and linear, both operated the same. The
glare removal occurred when the filters were 90 degrees from each other.
Now this experiment was dealing with a single source reflection.
That experiment makes me disagree with Piers (sorta).
My theory - since the ring flash will potentially produce a ring of light,
it's not a single point source anymore. It may be the fact that a linear
polarizer can handle the reflection from one angle, but it would have to
handle it from 360 degrees, ergo, a circular polarizer.
My theory is worth what you paid for it.
Jay
>Yes, I think he is using it that way - but I think he also reveals why the
>polarizers are not linear when he says "The filter ... does not require
>rotating for best effect". If they were linear polarizers, you would have
>to align them to avoid the undesired reflections - but you could only do
>that when the flash fires (the modelling lights are not of the same
>intensity as the flash tube). My reaction time is not what it was!
>
>--
>Piers
<SNIP>
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