Archived posting to the Leica Users Group, 2000/02/13
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]>"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> At 12:57 PM 2/13/00 -0800, Mark Rabiner wrote: >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 > Jim is writing: The interesting point is that Ashai stated, unequivocally, that filters can cause ghosting and reflections, and that they have solved the problem by making a different filter. Two facts. Filters cause ghosting and reflections. Ashai's new design is "supposed" to remedy the problem. If it had been so good, the patent would have run out, and everyone would be making them now. But alas... filters still cause ghosting and reflections. Ashai's design didn't work. Best solution... use filters, but be careful where you point them. Jim