P3D Fluorescent "green" suppression filter

[John Toeppen <toeppen@xxxxxxxx>]

An ionic doped glass called a "holium" glass or a "dydinium"(sp?)
contrast enhancing filters can be used to balance the green out of
mercury light. Hoya sells these as raw filter glasses V30 and AC-44. 
The faintly purple glass is sold as FLD by Hoya for fluorescent light
correction.  This filter is great for indoor events using fast negative
or slide films.

The abosrbtion band is 10,000:1 for 510nm and 100:1 for 578.  The AC-44
totally absorbs sodium yellow and near IR, making it a favorite of glass
blowers.  Such ionic glasses accomplish their work via discrete atomic
absorbtions.  Gel and plastic filters use dyes that do not have these
narrow line properties.  Effects are fun, but getting the shot "right"
is better than trying to fix it later.  Effects and electronic
enhancements also work best when you have something to work with.

John Toeppen
http://members.home.net/toeppen/index2.htm
I have posted a few more pages as jpg and jps


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