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09-16-2011, 07:56 PM   #16
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QuoteOriginally posted by ManuH Quote
OK but how is SMC defined? I mean all Pentax lenses are designed smc and we know that some lenses have special coatings like aero bright on the *smc* Pentax DA* 55mm f/1.4 SDM. I'm sure the smc formula was improved since it was first introduced. The DA 15mm and 35mm seem to resist flare better than the 21mm and 40mm for example. So smc is just a generic name. I would believe that all modern lenses are multicoated, the Tamron 18-250mm sure is as it is reasonably flare resistant (for a zoom). And it would make no sense economically to make this lens with Pentax coatings when the Tamron works just as well.
Actually, there have been some Pentax lenses produced without SMC coating. It is defined and patented as Super-Multi Coating. The few budget lens produced without it still got non smc multi-coating. Ghostless coating is another coating added to the rear element and is applied to certain lenses. All Ltd lenses have it. The SP Super Protect is added to the front coating to reduce dirt smears etc. The Aero Bright is the newest of the bunch and there is next to no information about it except it is used in the DA* 55 and DA* 60-250mm.

SMC is a 7-layer process.

About Super-Multi Coating (SMC)


Edit: Here is a list of non-smc k-mount primes and zooms compiments of dimitrov.

http://kmp.bdimitrov.de/lenses/primes/_non-SMC/index.html

http://kmp.bdimitrov.de/lenses/zooms/_non-SMC/index.html


Asahi Optical/Pentax were always pushing the envelope on coating development. The Coatings on the Takumar was evolving and there were changes to the coatings during the production span of some of the Super Taks as well as optical changes in some cases. Likewise, the SMC was improved between 1971 into the last decade several times. How much was serious improvements and how much was to renew patents only Pentax knows. They have been very secretive about there coatings. I have an ongoing thread to post information as it comes available.



These milestone quotes are from the Asahi Optical Historical Club.

QuoteQuote:
1971 - Super-Multi-Coating
World's first multi-layer anti-reflective coating on consumer lenses. This patented technology made possible high-quality wide-range zoom lenses.
All competitors owe Asahi Opt. Co. this technological breakthrough.
QuoteQuote:
1992 - Ghostless Coating
World's first and unique anti-reflective coating allowing no flare at all in daylight and negligible flare in nighttime shots with direct light entering the lens. It is employed on some critical elements in FA* and Limited series lenses.
http://www.aohc.it/milestone.htm


Last edited by Blue; 09-16-2011 at 08:06 PM.
09-17-2011, 10:01 AM   #17
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QuoteOriginally posted by Blue Quote
Actually, there have been some Pentax lenses produced without SMC coating.
Yes, but any recent lens? Even kit lenses are smc nowadays.
09-19-2011, 08:01 AM   #18
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QuoteOriginally posted by ManuH Quote
Yes, but any recent lens? Even kit lenses are smc nowadays.
I didn't say the new kit lenses didn't nor did I say old kit lenses didn't. To get back to the original point, if the DA 18-250mm says it has SMC on it, I have no reason to believe it has the Tamron proprietary coatings instead. Furthermore, the DA 18-250 not only labeled as SMC, it was marketed with Super-Multi Coating as well just like DA lenses still in production are.
09-19-2011, 08:48 AM   #19
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The problem with the 18-250 coating argument is that it's never resolved, because there's no conclusive proof either way. Yes, Pentax says it's SMC, but it looks like a Tamron coating (I'm not the only person who's stated this). I decided that it doesn't matter when I looked at samples from both lenses, specifically intended to show flare, colour and contrast. I saw no differences, so to me it's academic. I searched for the post with the test photos on DPR, but I couldn't find it. Their search engine is pure crap.

Coatings are not a reason to choose a Pentax 18-250 over Tamron. Choose based on availability, price and warranty. Lens corrections are available with Pentax lenses only, but corrections are available for the Tamron lens with some p-p softwares.

09-19-2011, 09:12 AM   #20
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QuoteOriginally posted by audiobomber Quote
The problem with the 18-250 coating argument is that it's never resolved, because there's no conclusive proof either way. Yes, Pentax says it's SMC, but it looks like a Tamron coating (I'm not the only person who's stated this). I decided that it doesn't matter when I looked at samples from both lenses, specifically intended to show flare, colour and contrast. I saw no differences, so to me it's academic. I searched for the post with the test photos on DPR, but I couldn't find it. Their search engine is pure crap.

Coatings are not a reason to choose a Pentax 18-250 over Tamron. Choose based on availability, price and warranty. Lens corrections are available with Pentax lenses only, but corrections are available for the Tamron lens with some p-p softwares.
Pentax says its SMC. It could be that Tammy lenses have the SMC. I haven't said that the coating was a reason to pick between the 18-250 lenses, just that the DA says SMC on it and it was marketed that was as well. It is listed as an SMC lens at Dimitrov's site as well. It could be that Pentax lied about it when the labeled the lenses and promoted it.

The point of this link http://rick_oleson.tripod.com/index-166.html is that you can tell about the coating by merely looking at it.

Last edited by Blue; 09-19-2011 at 09:18 AM.
09-19-2011, 11:53 AM   #21
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QuoteOriginally posted by Blue Quote
Pentax says its SMC.
I tend to think that these days "smc" is a pretty generic designation for a multitude of multicoating designs. Multicoating is not new anymore, even cheap filter maker advertise it. The Tamron lenses are certainly all multicoated, probably not with the same formula as Pentax but not different enough to remove the smc label from the 18-250mm.
09-19-2011, 12:01 PM   #22
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QuoteOriginally posted by ManuH Quote
I tend to think that these days "smc" is a pretty generic designation for a multitude of multicoating designs. Multicoating is not new anymore, even cheap filter maker advertise it. The Tamron lenses are certainly all multicoated, probably not with the same formula as Pentax but not different enough to remove the smc label from the 18-250mm.
Sure all manufactures have a multi coating now. They had to. Nikon even balked and tried to say that there was no way Pentax was doing the 7 layer thing in 1971 but Nikon was wrong and had to step up. However, SMC is not generic. Super-Multi Coating and SMC are a Pentax thing. I don't really know why you think Pentax would scarp industry leading chemistry in favor of some generic stuff.

Getting back to the original post, there shouldn't be any difference in the tow 18-250 lenses except from sample variation. Even if they have different coatings, Tamron was known for their good 3rd party coatings and the differences in it and the SMC would probably be minimal in this case.
09-19-2011, 12:26 PM   #23
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QuoteOriginally posted by Blue Quote
However, SMC is not generic. Super-Multi Coating and SMC are a Pentax thing. I don't really know why you think Pentax would scarp industry leading chemistry in favor of some generic stuff.
That's not what I was saying.

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