Has anyone besides me noticed how little information there is available on some of the specialty coatings used by Pentax? The SMC coating is also limited and apparently had undergone numerous revisions since the early 70s. Some rumors say it was originally designed at the request of Japanese police for traffic cameras.
The
Ghostless Coating was announced in 1992 and is considered a milestone for Pentax. It was apparently 1st used in 1997 on the the FA 43mm ltd and all subsequent limited lenses as well as certain * lenses. However, besides the LTD lenses, the other lens it was used on is unclear.
SP Coating The front surface of the optics is treated with the Pentax-original Super Protect (SP) coating. Applying a special fluorine compound to the lens surface through a vapor deposition process, this coating effectively repels dust, water and grease, making it easy to wipe off annoying stains such as fingerprints and cosmetic marks.
The
Aero Bright Coating enhances image-description performance by effectively reducing reflections over a wider wavelength range. Compared to conventional multi-coatings, this new coating greatly improves light transmittance in the lens, while drastically reducing flare and ghost images that deteriorate image quality. It is an original lens coating using a silica aerogel with uniform porous structure as a base material to produce clear high-quality images by assuring and outstanding anti-reflection performance over a broad range of wavelengths
. It is currently used on internal elements of the DA* 55mm for improved light transmission and reduced flaring and ghosting. Apparently the DA* 60-250mm also has the A.B. It is used on the new 645D lenses as well.
Update as of 2012:
Pentax released a new coating called the
HD coating, which offers better reflectance (i.e. less ghosting/flare) compared to SMC, and it is more durable than Aero Bright and thus suitable for use on the front element as well as other elements.
| SMC | HD | Aero Bright |
Reflectance | - | + | ++ |
Durability | + | + | - |
Cost | ++ | + | - |
That is all I've turned up on these. However, Pentax has been close to the vest on Coatings all the way back to the 50s. This info is from Pentax Imaging, Dimitrov and Pentax press releases.