P3D green night correction

[John Toeppen <toeppen@xxxxxxxx>]

Even "Daylight" FL lamps don't meet the
> photographic definition of "daylight".  

Film alone will not correct for this.  Filters can do rather well.

Mercury lamps (fluorescent lights & outdoor vapor lamps)
produce a strong green line at 546nm.  Multivapors have strong yellows
and sodium vapor lamps emit entirely at 589nm. How convenent it it that
"holium" glass absorbs these wavelenghts. Hoya sells filters for this
purpose, and they are pretty good.  Now all you need (maybe)is two in
series five adapter rings. (note: 2" squares of Hoya V-30 are too dark
of a purple for this use).

John Toeppen


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