[Not a Number]

I believe Hoya still owns the Pentax Medical side, maybe even the "PENTAX" brand name. I recall there was some speculation a few years back that Ricoh was going to lose the rights to use the PENTAX brand name.

[Ausable]

Hi 🙂

I have a DA* 16-50 without HD coating and I recently purchased an SMC DA 50-200 for my wife as a light zoom gear.

I was wondering if using the latest Hoya HD MKII filter could improve the sharpness and CA. Something like converting the lenses with the same qualities of Pentax HD lenses.

I do know that it’s mostly for protection but I guessed if Pentax is actually using the same HD coating on the lenses that are sold in these filters and it’s been recognised that HD lenses are a step sharper than SMC. And Hoya has strong ties with Pentax. So….

They ain’t cheap and I wonder if that’s a wise or a useless idea as many say that filters make the lens less sharp.

PS: all my other lenses are HD and I even mounted a filter on the HD 35/2.8 macro for mere protection.

https://hoyafilter.com/product/hd_mk_ii_protector/

In Pentax Forums' two comparison reviews of SMC/HD FA and DA Limited lenses, the HD coating improved resistance to flaring and ghosting but chromatic aberrations were not lessened. The comparisons did not address sharpness. A filter with improved coatings would likewise reduce the tendency for flaring and ghosting of the filter, but it would leave the characteristics of the basic lens untouched.

[mlag]

PENTAX Lens Technology / Lenses / Products | RICOH IMAGING


The HDcoating reduces reflectance. On both lens and filter the light gets easier into the glass (is not partially reflected unlike a glass mirror, we have all seen reflections in windows of buildings....it’s not what we want on a lens).
Note also that reflectance varies by wavelength (color of light), so ideally a coating should treat equally good all visible light colors...but it might filter UV and IR as a benefit.
Hence for the filterglass there is less light loss with HD coating (that’s ideal for a protective filter).., however after the filter it can still be partially reflected by the lens without coating...
Other coatings might reduce flare, ghosting, dispersing light...(avoid bending light rays in wrong direction...), remember it are multilayered coatings. Such off the track light might indeed adversely affect negative picture quality.
But note, coatings work on "one" lens surface only, not on the next layer of glass... hence a filter in front does not improve the glass after it.
An UV, IR ...filter will remove part of unwanted light, but the remainder (=visible , picture light) still has to travel through the lens behind it and will be affected by the by the quality of lens glass...

Note that it affects small percentage of light...<<1% . See chart on above ricoh website (vertical axis is 0..1% reflectance)
From that point of view don’t overly worry...but all bits help,
and in some conditions effect might be visible , but in many/most not or hardly...

[mikesbike]

In other words, the filter with the best posible coating can only be as good as having no filter (100% transmission, 0% reflection).

This is the most right-to-the-point and correct answer. It is also indicative, if wanting or needing a protective filter for a lens, this type is more expensive but is the way to go in order to avoid unwanted side-effects from the filter.

Some filters are formulated to deliberately alter imaging results. One such is the "skylight" filter, a type also often used as a protective filter, but it is formulated to cancel certain green or blue reflections to improve skin tones. It is then also useful for adding a slight warming effect without reducing incoming light to a meaningful degree, which can be a benefit for lenses otherwise having a "cold" or "clinical" look, which are otherwise good, sharp lenses.

---------- Post added 11-17-22 at 04:45 PM ----------

And where is anyone recognising that HD coated lenses are a step sharper than SMC coated lenses with the same optical design?

I was surprised years ago to find very noticeably improved performance from the new HD WR version of the DA 55-300mm f/4-5.8 WR lens when I got the newer one to have its WR advantage. As to test results, this improvement is again confirmed in the PF lens testing of the 3 basic kit lenses, the DA 18-55mm WR, against the two newer ones that are identical except for the HD coatings- the DA-L 18-50mm WR and the HD DA 18-55mm WR. Go to the top of the forum page, the "Lenses" category tab will bring down a menu which includes "Pentax Lens Reviews" to click on. Then scroll down to DA zoom lenses, then to the Pentax HD DA 18-50mm WR, then click on the button for the in-depth staff review.

This review is very thorough between these lenses, even at one point throwing in the well-regarded HD DA 16-85mm WR just for the sake of comparing against a much more expensive option. The Sharpness section of the review is very interesting. The end results were overall- better for the newer DA-L and the HD version of that lens, over the older DA 18-55mm WR. But the surprise for the testers was their finding of definitely better performance of the HD version over the other two. This was again stated in a paragraph of its own at the conclusion of the Sharpness testing. Based on my own experience with my two DA 55-300mm lenses and discovering the superiority of the HD version over its sibling, this was no surprise to me, but gratifying in that my observation was not a fluke.

It makes sense, because the HD coatings improve against factors that can cause a reduction in sharpness. I like the two newer lenses and their ultra-compact concept. I had the older DA 18-55mm II for years and gave it away to friends. I also found the new AF to be superior and more reliable, and I have been rather dismayed lately to find only the old DA 18-55mm WR model being offered.

---

Last edited by mikesbike; 11-17-2022 at 05:01 PM.

[gatorguy]

I am sorry, you are quite wrong, Hoya is the owner of Pentax and the Pentax brand name, but they sold the camera section to Ricoh and allowed them to use the brand name, so these camera's are Pentax-branded camera's from Ricoh.
Hoya did acquire Pentax for the medical part of that company. Both Hoya and Pentax produced medical optics and that is why Hoya wanted to merge with Pentax. Hoya was, as we know, not interested in camera's.
A HD filter attached to an SMC lens, does not turn that lens into HD. Hoya's HD is completely different from the HD on a Pentax branded lens.

QUITE wrong might be a bit overstated. The Pentax we all know here is not owned or operated by Hoya any longer. But yes there are some Pentax-branded products that are sold by Hoya. Just not our cameras. Or lenses.

[StiffLegged]

... But the surprise for the testers was their finding of definitely better performance of the HD version over the other two. This was again stated in a paragraph of its own at the conclusion of the Sharpness testing....

Thanks for that, hadn't seen it before although I had read there was no improvement in sharpness noted in the PF staff review of the SMC vs HD versions of both the FA Limiteds (31, 43 & 77mm) and the DA Limiteds (15, 21, 35, 40 & 70mm); just improvements in flare resistance and bokeh. Such is life.

[UncleVanya]

In all honesty other than the 18-50 I don’t think any other hd vs SMC comparison has shown sharpness differences. I owned both and I couldn’t tell much difference other than the hood and coating improved flare handling. Mechanically my HD copy was also smoother but it could just be due to it being new vs used for the DA L SMC.

[mikesbike]

Well, flare can definitely be one sharpness killer, and often the flare is not actually visible, but still enough to reduce clarity. Contrast can also be increased, further enhancing clarity. My experience with the HD DA 55-300mm WR lens was also shared by others who had the same experience, and even to the point of saying it was like a completely new lens design.

Not to say older SMC designs are obsolete or not very good, but unless one is really into maximum star effects, the new HD coatings seem to be very beneficial.