Hoya Pro 1 SMC vs Pro 1 Digital Filters

Since this is an often asked question, I contacted Hoya Tech Support. Here is an email response from them about the differences between Hoya Pro 1 SMC and Pro 1 Digital filters as well as between Hoya and Kenko filters.

"The Pro 1 SMC filters were thin filters (designed to avoid vignetting on wide angle lenses) with an average light transmission of 99.7%, and front filter threads (so you could use a standard lens cap). The multi-coatings on the Pro 1 Digital filters have been redesigned to perform better with the sensors on todays DSLR cameras, are thin filters to avoid vignetting, and still have the front filter threads, so you cna use a standardlens cap. They give you an average light transmission of approximately 98%.

The main difference between the Hoya and kenko Pro 1 Digitals, is the name. In Japan, Hoya filters are sold under the Kenko brand name, while elsewhere in the world they are sold under the Hoya name.

I hope this will help in making decisions regarding Hoya filters."

Glenn Nash
Technical Service Representative
THK Photo Products

Thanks Jim, hard to find real info on the differences side by side like that. Is this in reference to UV filters or CPL's or all filters.

DDCSD wrote in post #5088238
Thanks Jim, hard to find real info on the differences side by side like that. Is this in reference to UV filters or CPL's or all filters.

I assume it is for all Pro 1 filters including the CPLs. However, I didn't specify when I asked the questions.

My Digital Pro 1 Circular Polarizer has served me well.

Tsmith wrote in post #5089250
My Digital Pro 1 Circular Polarizer has served me well.

I'm liking mine, just got it last week.

jhom wrote in post #5088123
"The Pro 1 SMC filters were thin filters (designed to avoid vignetting on wide angle lenses) with an average light transmission of 99.7%, and front filter threads (so you could use a standard lens cap). The multi-coatings on the Pro 1 Digital filters have been redesigned to perform better with the sensors on todays DSLR cameras, are thin filters to avoid vignetting, and still have the front filter threads, so you cna use a standardlens cap. They give you an average light transmission of approximately 98%..

I find it remarkable that redoing the coatings 'for digital' results in LESS light getting thru the filter (98% vs. 99.7%). Makes you wonder where it goes if it does not pass thru the filter...would that not indicate more contrast-reducing light and more flare elements bouncing around between air-glass surfaces ?!

Wilt wrote in post #5089465
I find it remarkable that redoing the coatings 'for digital' results in LESS light getting thru the filter (98% vs. 99.7%). Makes you wonder where it goes if it does not pass thru the filter...would that not indicate more contrast-reducing light and more flare elements bouncing around between air-glass surfaces ?!

I've sent a followup set of questions specifically asking about the reduction in light transmission in the Pro 1 Digital filtes. Let's see what Hoya says about it.

Indeed 98% is not that good. That would be the same as the old 3 layer MC Hoya HMC.

I am very surprised by this. Please keep us up to date with any further details and I'll update the filter FAQ pages as needed. Also I'll be checking to see if any of my filters are Pro 1 Digital filters rather than SHMC Pro 1.

Looking at a couple of UK distributors they seem to be using SHMC Pro 1 and SHMC Pro 1 D interchangeably. By definition the SHMC coating should be 99.7%. If Hoya are right then their retail outlets are misleading.

Well, I got a response to my question about the reduction in light transmission in the Digital versions of the Hoya/Kenko filters. The question was whether the reduction in light transmission in the Pro 1 Digital filters was a design limitation or purposeful design. Here is the response I got back from the Hoya Tech Service Rep:

"Honestly I belive it would be a design limitation, but that is something Japan has never fully clarified."

Now the question is whether this light transmission reduction is a significant difference to affect IQ? Also, a question could be asked if the multicoating difference in the Pro 1 SHMC filters have any negative affects ont the digital sensors?

Any optical engineers out there with any comments?

thanks jhom, this really help me out.

jhom wrote in post #5093341
Well, I got a response to my question about the reduction in light transmission in the Digital versions of the Hoya/Kenko filters. The question was whether the reduction in light transmission in the Pro 1 Digital filters was a design limitation or purposeful design. Here is the response I got back from the Hoya Tech Service Rep:

"Honestly I belive it would be a design limitation, but that is something Japan has never fully clarified."

Now the question is whether this light transmission reduction is a significant difference to affect IQ? Also, a question could be asked if the multicoating difference in the Pro 1 SHMC filters have any negative affects ont the digital sensors?

It seems that Hoya really blew this one!

On one hand, they paint the digital filter edges of the glass black to reduce the amount of light which reflects off that edge, in an attempt to further reduce the amount of light which could eventually reflect around due to the sensor reflectivity.

On the other hand, they apply coatings which are LESS efficient than the non-digital SHMC filters, neutralizing any benefit which might have been obtained via the black edges (for which they had never quantified the benefit!)

Certainly is very interesting information and its my understanding that they have discontinued the Hoya Pro 1 SMC Circular Polarizer line.

I was told it was replaced with the Hoya Pro 1 Digital Circular Polarizer.

Filters are supposed to filter light out though, correct? There may be a valid reason for the lower light transmission. Keeping some bad light out?

Would be nice if they would actually state the reason. I would doubt they would redesign a filter line to make it worse and then charge more for it. Why not just rename the old one and charge more?

I am very impressed with my Pro-1 Digital CPL, I know that.

Well I do know that the coatings on the Hoya Digital Pro 1 work really well controlling flare. I've processed hundreds of photos using the filter which I've consider the clarity and sharpness results to be very good.

I've been tempted many times to order the B+W equivalent but in the F Pro that has front threads just the verify the IQ first hand. After that conclusion one of the other would go up for sale.

Anybody wanna loan we their B+W CPL for testing? I'll gladly pay the shipping both ways _

I've seen B+W F Pro (not slim) owners claim this filter won't vignette on the Canon EF-S 10-22mm at 10mm but haven't seen any results.

I would like to buy a Hoya CPL filter as well and still not sure which one to get and from where.
I have B+W 77mm Kasem... the most expensive one, it is really amazing amazing but i can't attach another filter on it, only before, so i can't use it with my GND filters and that is the only main problem that i would like to buy another CPL.