Archived posting to the Leica Users Group, 2000/02/13

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Subject: Re: [Leica] Re: UV Ghostless filters
From: Mark Rabiner <mrabiner@concentric.net>
Date: Sun, 13 Feb 2000 12:57:09 -0800

"A.H.SCHMIDT" wrote:
> 
> At the time, when the Pentax Spotmatic was released, Pentax advertised a Ghostless
> UV filter.
> 
> This filter did not have a flat ground glass, but it was curved. A similar curve
> like the front element of a lens. Pentax in their leaflet says:   "The Ashai
> Pentax Ghostless Filter is a breakthrough in filter design. With this curved UV
> filter, the image light reflected back to the Ghostless filter and retransmitted
> through the lens, forms a duplicate image in the air, thus eliminating a ghost
> image on the film plane."
><Snip> 
Would not introducing a curve into a filter make it act like a lens? I'm
surprised it did not change the "power" of the lens!!
Mark Rabiner