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Re: [Rollei] ARGH! Sorensen and the Filter Myth!

At 05:26 PM 02/21/2001 -0500, you wrote:
>> From: Marc James Small <msmall  >
>> Reply-To: rollei  us
>> Date: Wed, 21 Feb 2001 13:47:47 -0500
>> To: rollei  us
>> Subject: Re: [Rollei] ARGH!  Sorensen and the Filter Myth!
>> Again, professionals -- who live by their gear -- virtually never use
>> filters save for color correction.
>And, when using flash, we filter the flash, not the camera lens!  Most pro
>grade studio flash equipment has UV coated flash tubes as standard or as
>an option.  They're worth a few bucks extra.
 Different effect. UV filters on the strobe lights prevent florescence of
the material being photographed. This can have a very significant effect on
the appearance of clothing, for instance, which has been treated with
optical brighteners (as in washing detergent). The brighteners fluoresce
blue, causing a color shift which is very apparent in the resulting photos.
A filter on the lens has no such effect. Its purpose is to prevent exposure
of the film by UV reflected from the objects being photographed. Color film
can suffer a shift in color balance from UV since the blue layer is often
more sensitive to UV than to blue, and B&W materials are sensitive to near
UV. The result in color is a shift toward blue which is not apparent when
looking at the original scene visually. 
  UV filters on the light source obviate the need for them on the camera,
but again, they serve a different purpose. 
- ----
Richard Knoppow
Los Angeles,Ca.