Originally posted by northcoastgreg I find plenty of reasons to reject "it is Tamron's coating" hypothesis, not least of which is what Ricoh's U.S. site explains in regards to the DFA 24-70:
Nor do I believe any coherent reason to believe that SMC refers to "any multi coated process." The old K-Mount Takumars lacked the SMC coatings, but it is thought that some of them may have been multi-coated. SMC does not equal just any multi-coating. It is a unique Pentax developed and patented technology.
Such passion for Pentax consumer coatings .!!
Pentax 'superior' coatings have been since 1997
Ghostless first used in the 43 limited
and Aerobrite as used in the da* lens
PENTAX Lens Technology / Lenses / Products | RICOH IMAGING
7layer .998 light transference might have been unique and patentable in 1971 but please its cheap and common as muck today .... You'll not find a modern lens that isn't superior to the original Pentax 1971 coatings and that includes the like of the da 18-55 SMC. !!
There is no written evidence that teh Pentax da 18-250 SMC has Tarmon coatings other than its color cast matches all Tamron lens and is different from all Pentax made SMC lens.
To me that pretty conclusive evidence.
How Lens Coating Works https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/138601-pent...8-250-a-2.html
As to the 24-70 coating Pentax say
HD Coating to improve image description *2
The lens is treated with high-grade, multi-layer HD Coating.* Compared with conventional multi-layer coatings, this PENTAX-original coating assures higher light transmittance and less reflection to deliver bright, high-contrast images free of flare and ghost images, even under demanding lighting conditions such as backlight. *2:HD stands for High Definition.
Notice the hyphen between PENTAX-original ?? this means any coating Pentax defines as High |definition is a HD coating , Also they say "higher light transmittance and less reflection" but neglect to say compared to what ?
It doesn't mean it not a great lens but the rose coloured specs do not make it look better
See what an owner says about the coatings and behavior (someone not trying to sell you one)
https://www.pentaxforums.com/lensreviews/hd-pentax-d-fa-24-70mm-f28-ed-sdm-wr.html
Last edited by awaldram; 02-09-2016 at 07:45 AM.