Re: filmscanners: Re: looking at the Sun

["Alan Tyson" <AlanTyson@bknowl.freeserve.co.uk>]

Infrared is also a serious, if not worse, hazard. Glass is
fairly transparent to it, as shown by greenhouses, passive
solar panels, the burning of holes with magnifying glasses,
and the feasibility of IR photography with ordinary lenses.

Most glasses absorb UV much more strongly than IR. Most of
the materials used for sun viewing and photography (eclipse
goggles) have a  (log10) density of 5-8 for UV and visible,
and less than 5 for IR.

The worst of the lot is fogged colour negative film, which
is fine in the UV & visible, but lethal to eyes because it's
transparent to IR.

NASA's web site has lots on this under solar eclipses.

Regards,

Alan T

----- Original Message -----
From: Laurie Solomon <laurie@advancenet.net>
To: <filmscanners@halftone.co.uk>
Sent: Sunday, February 04, 2001 5:13 PM
Subject: RE: filmscanners: Re: looking at the Sun


> True, but only a very small amount.  UV filters filter
only enough to keep
> the image from displaying haze and color shift effects but
not enough to
> protect eyes from the harmful effects over any prolonged
period of time like
> more than 5 minutes duration or great accumulations of
short duration
> periods ( Here I am speculating since I do not know if the
harmful effects
> are cumulative).