This significant "SMC" coatings improvements over the years myth needs debunking. Original uncoated lenses ( pre WWI era ) reflected about 5% of the light on each air glass surface. Single coating introduced in the 1940's which was very noticably better got that reflection down to about 1% per air glass surface. When Pentax unleashed SMC coatings, the very first version of SMC, no less, in 1971 on the screwmount lenses, the reflection figure had been reduced to only 0.2% reflection per air-glass surface. While the reduction from 1% to 0.2% made a big difference on lenses with many air glass surfaces, on some lenses, mostly 4 and 5 element telephotos, the SMC coatings did not offer hardly any or no visible differences over single coatings. This is simple because the single coatings had already acheived excellent overall performance in those basic design lenses.
Getting back to SMC "improvements" over the years, most of them have been in the area of color correction and coating durability. I dont know what the current specification is for the latest SMC coatings, but when the original was already 99.8% transimission, there was/is not much room for improvement, as the number was already excellent. There may possibly be some visible improvement on very high element designs like most zooms and some wide angles over 10 elements. But even so, with a 10 element lens and the original formula SMC coatings of 1971, you ended up with 95% transimission of the optical system so even "perfect" SMC of 2009 would only offer a very small difference in system reflections, a figure less than the one noted in 1971 as being invisible with low element systems and SMC vs. single coated lenses. 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. DOES ANYONE KNOW THE SPECIFICATION ON THE BEST EVER ( LATEST ) PENTAX SMC COATINGS ? JC O'Connell [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Graydon Sent: Thursday, April 16, 2009 9:44 AM To: Pentax-Discuss Mail List Subject: Re: DA55* 55/1.4 follow-up On Thu, Apr 16, 2009 at 09:24:54AM +0100, mike wilson scripsit: > ---- Scott Loveless <[email protected]> wrote: [on comparing 50mm lenses] > > My money's on the M50/2. Wouldn't that be a bitch if it were true? > > Hmmmm. High build quality verus computerated optical design. Old but > high QC versus new and unknown. Really hard to call on that one, even > before we start wittering about stuff like bokeh. Think I'll go buy a > lottery ticket. The DA coatings are better than the FA coatings; I'd be more than a little surprised if the FA coatings weren't better than the M coatings. Can't leave that out. -- 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.
