Re: Kings Inn viewer done

[rlrylander@xxxxxxx]

Alan Lewis wrote:

> E R Swanson wrote:
> >
> > My question, Alan supplied a little UV filter with the Saturnslides. How
> > essential is this? Should I be concerned about the amount of UV coming off
> > a fluorescent tube?
>
> I've wondered this myself.  I use the UV filter just as a precaution in
> case there is any possibility of exposure.  The long discussion a while
> ago on P3D didn't come to any conclusion on fluourescent lamps and UV.
>
> So I err on the safe side.
> --
> Alan Lewis
> mailto:3-d@xxxxxxxx
> http://members.home.net/3-d
> Home of Weekend Stereo Projects
> New stereo viewers & Stereo Wedding Photography

A good source of information about fluorescent lamps is the JKL Components
Corporation web site (www.jkllamps.com).  Click on Application Notes and a
number of ".pdf" documents are available.  In particular, "Understanding Cold
Cathode Fluorescent Lamps (CCFL's)" is very useful.  A chart of conversion
efficiencies shows that typically about 20% of the 253.7nm ultraviolet energy is
converted to visible (380-780nm) light by the phosphors.  This doesn't
necessarily mean the other 80% is emitted (much is reabsorbed and lost as heat),
but there is still significant UV output from "white light" fluorescent lamps.
I absolutely agree with Alan to err on the safe side.

"Lens protecting" UV filters are pretty cheap and can easily be placed behind
the eyepiece lenses of a viewer, or Light Impressions
(www.lightimpressionsdirect.com) sells acrylic sheets specifically designed to
protect against UV.  "Acrylite OP-3AR" is supposed to filter out 98% of UV
radiation.  An 8x10" sheet is $6.95.  This can easily be cut and places between
the bulb and diffuser - might as well protect your slides as well as your eyes.

Richard Rylander