[Athanassios]

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/

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Last edited by Athanassios; 12-19-2022 at 10:32 AM.

[simon_199]

Hoya no longer owns Pentax. Interesting theory, nevertheless

[Athanassios]

Hoya no longer owns Pentax. Interesting theory, nevertheless

Just made me a little more embarrassed than before. 🤭
You’re 11 years long right. (Edited the word to “ties” from “owns”)

[ehrwien]

My stance on the matter of (protection, UV, etc.) filters is that you introduce more air/glass // glass/air surfaces which increases the risk of unwanted reflections, but also makes you lose light, more so with cheap filters than with expensive ones. The question is whether the light you lose that way is wanted or unwanted (glare, CA, ...). And I'd guess that even with the more expensive filters, even when some of the lost light is unwanted, you'll always also lose at least a little bit of wanted light. I've got no data to back this up, those are just my feelings.

On the matter of the "HD" designation, even with the coincidences of the filter being from Hoya and their past with Pentax, it would be possible but unlikely that it is the same coating. I don't think using "HD" in reference to lens coatings is protected or even protectable in patent/trademark law.
I think this feeling is further reinforced by reading and comparing the descriptions from Pentax for their HD coating and Hoya for the coating of their filters. What I found: Hoya claims

"HD HIGH-TRANSMITTANCE COATING
16-layers anti-reflective multi-coating on both sides of the filter glass"

"comes with HOYA’s top quality HD glass, which is a special, chemically enhanced optical glass"

, which seems to call both the glass and coating "HD", while Pentax says here about the HD coating:

Compared with a conventional seven-layer coating applied by a vacuum evaporation process, the new HD Coating forms an eight-layer coating with a uniform layer thickness, created by a high-precision, ion-assisted evaporation process. This is further reinforced by a ninth coating added to the outermost layer by a vacuum evaporation process.

When you're not in an environment that you don't want your front lens to be exposed to, like on a windy beach or in a dusty room, you can certainly use a filter for protection, but otherwise I would trust the lens hood to prevent mechanical damage and leave filters other than ND or polarizing filters off if you don't want them for the effect they have on your pictures.

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Last edited by ehrwien; 11-17-2022 at 01:02 PM.

[AfterPentax Mark II]

Hoya no longer owns Pentax. Interesting theory, nevertheless

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.

[StiffLegged]

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.

Putting a piece of flat glass in front of a lens is not going to improve sharpness or chromatic aberration (CA). Putting a piece of HD coated flat glass in front of a lens is not going to convert the lens to an HD coated version. Sorry!

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

[GUB]

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/

No
The HD coating means the actual surface coated absorbs light in a superior manner.
So your suggestion is if you add 2 glass surfaces (the filter) with a coating to help those surfaces will this help the other surfaces in the lens. The answer obviously is no.
Seeing you have some HD as well as SMC how about actually going out and setting up examples and see if in practise there is any major real life differences in the coatings.
But I get why you have protective filters on your lenses even tho I choose not to.

[CarlosU]

AFAIK the reason for coating a lens is to increase light transmission through the glass as much as posible, avoiding light reflection on the lens surfaces.
So the ideal situation would be 100% light transmission or 0% reflection, what a "perfect coated" filter would do. And that is exactly what you have in front of the lens without any filter.
In other words, the filter with the best posible coating can only be as good as having no filter (100% transmission, 0% reflection).
Once the light gets in to the first element and pass through the rest of the lens, the lens own coating is what define how much light passes and how much is lost by reflection.
In conclusion, there is nothing a HD coated filter could do to increase light transmission through the lens. Even more, it surely decrease light transmission, at least by a tiny bit.

[pschlute]

I was wondering if using the latest Hoya HD MKII filter could improve the sharpness

Sir, if you want to improve sharpness, you should concentrate on focussing correctly. Putting another bit of glass between your lens and the subject is not going to help in the slightest.

[C_Jones]

The original lens is either HD or not. That primary designation defines that attribute. Other added filters do not change that designation.

[Athanassios]

Thank you all. You made me wiser and not a money waster.

✌🏻🙂✌🏻

[GUB]

Thank you all. You made me wiser and not a money waster.

✌🏻🙂✌🏻

As far as "money waster" goes I guess some of us are saying "do as I say" rather than "Do as I do" !!
Just blew $300 on a 1960s lens today!

[Athanassios]

By waster I meant it would give me nothing that I wished for.
✌🏻🙂✌🏻

---------- Post added 11-17-22 at 02:25 PM ----------

Putting a piece of flat glass in front of a lens is not going to improve sharpness or chromatic aberration (CA). Putting a piece of HD coated flat glass in front of a lens is not going to convert the lens to an HD coated version. Sorry!

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

As far as I remember even Pentax claims that HD is better for lens performance. Not to mention the various reviews from SMC and HD users.

[UncleVanya]

I would say the biggest advantage a high quality filter may offer is protection. Often a hood is as good or better but smudges and dirt come off easier with some nano coated filters than the original glass PLUS a scratched filter can be thrown away . That said, most of the time I don’t use them.

[GUB]

As far as I remember even Pentax claims that HD is better for lens performance. Not to mention the various reviews from SMC and HD users.

Yes that is called "spin"
I collect old Pentax lens and have a preference for the oldest least coated. Call me odd by all means but my point is, while there maybe a difference between these "originals" and the progression of coatings to where we are now , if you look at the gain per each advance it is barely visible.