Date:         Fri, 7 Aug 1998 07:21:01 -0700
Reply-To:     jim catterson <termite@ROCKETMAIL.COM>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         jim catterson <termite@ROCKETMAIL.COM>
Subject:      Re: Driving/Fog Lights [long]
Comments: To: vanagon@vanagon.com
Content-Type: text/plain; charset=us-ascii

  Why are blue lights all of a sudden the big rage?
>
> -Karl

just my two cents here but,  some big misunderstanding going on here.
karl is largely correct that blue light is not what anyone should be
looking for for any type of extra lighting.  the confusion stems from
a design of lense that was popularized by the italian company piaa.
their blue ion fog lamps only appear blue when they are not
illuminated.  once lit up,  the light is amber in color.  the lense is
a computer designed projection lense that gets its beam pattern and
diffusion from the shape of the lense and the reflector rather than
the previous practice of casting flutes into the lense to achieve a
certain pattern.  the projectors generally have more sophisticated
optics allowing more light from a given wattage bulb to reach the
street w/  less reflection.  many cheap copies of piaa's use a blue
dyed bulb so that it appears to be the same technology.  instead,  you
get bad optics w/  the wrong spectrum of light.  of course real piaa's
are $$$$.
most bosch and hella lights now employ a slightly more sophisticated
lense design than they used to but they are not cutting edge
technology [probably not even 90's tech] anymore.  they employ amber
or clear lenses that are heavilly fluted to get the optimum beam
pattern.  the bluish light seen in mercedes and other expensive cars'
headlights these days is a recent invention [for cars anyway] and
comes from extremely expensive gas discharge headlights that require a
higher operating voltage and somewhat complicated electronics to
operate.  this cannot be duplicated in a simple 12volt headlight.  no
matter what the bulb ads say.  i have found some piaa copies that
perform pretty well given the cost involved and still better than the
bosch or hellas
 cheers

jim catterson
91 syncro
93 ev gl          ny
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