Hi, the coating performance measurement is not SYSTEM because system performance varies depending on the number of air glass surfaces. The number I quoted for original 1971 SMC coatings was complete and correct, 99.8% transmission per air-glass surface. Do you have any data on the current/best/2009 SMC coating transmission percentage per air-glass surface? I really doubt its 10 times better than it was in 1971 for a figure of 99.98% like you suggest.
Secondly, I do not belive there has been a significantly or visible color error in all multicoated lenses before DA coatings came along. Some lenses may have shown color errors due to a number of reasons but I dont think it would be correct to say that all lenses have suffered from visible color errors before this DA coating came along. JC O'Connell [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Graydon Sent: Thursday, April 16, 2009 10:59 AM To: Pentax-Discuss Mail List Subject: Re: SMC COATINGS WERE FANTASTIC FROM DAY ONE IN 1971 - RE: DA55*55/1.4 follow-up On Thu, Apr 16, 2009 at 10:48:55AM -0400, JC OConnell scripsit: > NO, I am not saying that "improved" SMC coatings may never give any > visible flare performance over the original SMC coatings of 1971, but > it is only going to be visible on really high element count lenses if > at all, certainly not on prime 50mm lenses in the 5-8 element range > and only if the transmission percentage is/has significantly improved > from the 1971 figure of 99.8% which I doubt. Every high end binocular manufacturer in the world, including Pentax, claims a number like that for *system* performance, not single interface performance. I'd strongly suspect there's another nine in that number by now. There's also that the colour rendition is visibly different between FA and DA lenses. Something has changed in the colour transmission curves. Might be the glass, but quite possibly also the coatings. -- Graydon -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
