[Spock]

As the title says - what is the difference?

It seems to me that the Super HMC (Hoya Multi Coat) should be better as it has more coats and lets more light through.

What's special about the digital one? (It sounds more like a re-branded basic filter - ie. a marketing improvement).

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Last edited by Spock; 10-21-2009 at 09:01 AM.

[imtheguy]

I happened to have the comparison chart for the UV series in hand -

According to the marketing poop the Digital has an Anti-Aliasing coating. Somebody else will have to explain how that actually works.

Also the Digital is a thin mount with a 3mm ring instead of the 5mm ring on the non-digital filters. That part could actually be usefull.

[pacerr]

UV filters test - Introduction - Lenstip.com

Here's a very thorough UV filter test that indicates price alone may not be the best answer. There's a polarizer filter test on the same site. Lot's of good info in general too.

H2

[MattGunn]

I happened to have the comparison chart for the UV series in hand -

According to the marketing poop the Digital has an Anti-Aliasing coating. Somebody else will have to explain how that actually works.

Also the Digital is a thin mount with a 3mm ring instead of the 5mm ring on the non-digital filters. That part could actually be usefull.

Aliasing is a defect related to sampling frequency. If the lens produces sigfinicantly higher resolution image than the sensor can sample then you will get aliasing defects in your images (see here for a detailed description - Aliasing - Wikipedia, the free encyclopedia) Aliasing is moch more of a problem for digital photography due to the very regular geometric distribution of the pixels on the sensor. A common defect caused by aliasing is moire patterns (again see wikipedia article here: Moiré pattern - Wikipedia, the free encyclopedia).
As far as I'm aware most camera manufacuters prevent aliasing by incorporating a filter in front of the sensor which "spoils" the image from the lens in a controled way. Although this sounds like it is reducing your cameras resolution it actually improves it. However as most cameras have an anti-aliasing filter built in, adding a second one in front of the lens is likely to reduce the resolution overall. It is probably not worth getting the special "digital" filter, the anti-aliasing filter in the camera will have been matched to the sensor and should perform better. Also "spoiling" the image twice will reduce the overall resolution.
It may be worth trying if you are regularly seeing moire paterns in your images though.

[Ash]

Great mini-tute, Matt.
The study referred to above does go against 'getting the best filter you can afford' but that's generally the advice to follow - the SHMC filters have more coatings and permit more light to pass through the filter, thereby altering the image quality the least.

They work fine with most lenses and have a better build quality than the DMCs. The 'optimised for digital' feature of DMC filters I think are just a gimmick (caveat above in Matt's synopsis) - even ultrawide lenses are not affected by the size of the SHMC filter ring due to lens design (like the DA 12-24).

[nater]

As the title says - what is the difference?

It seems to me that the Super HMC (Hoya Multi Coat) should be better as it has more coats and lets more light through.

What's special about the digital one? (It sounds more like a re-branded basic filter - ie. a marketing improvement).

There's a fairly good write up on this question here:

Hoya Pro1 Digital vs HMC Filters