[filmscanners] RE: HP PhotsSmart - questions

["Laurie Solomon" <laurie@advancenet.net>]

> Anti-reflection coating on the flatbed of a scanner has
> nothing to do with uncovered parts of the flatbed and
> everything to do with the fact that anytime the image forming
> light hits a glass-air surface there is the potential for a
> reflection (or backscatter) which will reduce the contrast of
> the image (non image-forming light hitting the unexposed
> parts of the CCD/CMOS).

I beg your pardon.  Are you saying that the light shinning through the
uncovered portions of the glass scanner bed does not tend to bounce off the
flatbed bed cover and scatter so as to create the backscatter you are
speaking of? If it does, which I have always been told was the reason why
one should mask the uncovered portions of the bed, then it does have
something to do with the problem and the reason why an anti reflective
coating might be used in large commercial grade flatbed scanners.  I never
said that it was the only reason or factor and agree that there may be many
such factors.  But I think that your articulation is a little extreme.

> -----Original Message-----
> From: filmscanners_owner@halftone.co.uk
> [mailto:filmscanners_owner@halftone.co.uk] On Behalf Of
> wbgilloolyjr@charter.net
> Sent: Monday, August 08, 2005 2:58 PM
> To: laurie@advancenet.net
> Subject: [filmscanners] Re: HP PhotsSmart - questions
>
> Anti-reflection coating on the flatbed of a scanner has
> nothing to do with uncovered parts of the flatbed and
> everything to do with the fact that anytime the image forming
> light hits a glass-air surface there is the potential for a
> reflection (or backscatter) which will reduce the contrast of
> the image (non image-forming light hitting the unexposed
> parts of the CCD/CMOS).  Any time you have light passing
> across a glass-air surface you will improve image quality
> (particularly contrast) by AR coating the glass.
>
> Mr. Bill
>
>

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