Re: polarizing filters with b&w infrared

[boblong@xxxxxxxxxxx (Robert Long)]

On Wed, 30 Oct 1996 17:06:49 +0000 (GMT), you wrote:

|polarizer should be used in addition to a no.25 or 29 red filter as =
well. My
|response is that if you look at the two photos , you would be hard =
pressed to
|notice any difference at all in contrast , very minimal at best. Also =
take

No significant difference in overall contrast, agreed.  The difference
is in haze penetration in the extreme distance and in sky darkening at
the horizon--which doubtless are two facets of the same syndrome.

|into account that 2-2 1/2 stops of light would be cut out with use of  a

HIE can take it.

| polarizer in addition to the light absorbed by a red or infrared =
filter. Not
|a good or practical combination of filters for these reasons and besides
|polarizing filters can only polarize visible light, not infrared light.

On the contrary, if you want a black sky, use of a polarizer can
materially darken the sky with a #25 filter, which is what I was
using.  The difference admittedly is only slight with the #87 filter.

Bob Long
(boblong@xxxxxxxxxxx)

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Topic No. 10