"Digital" CPL filters

[crisgil24]

I'm a SLR user and I'm looking into CPL's and I'm wondering if there's any difference between a labeled "Digital CPL" and just a plain non labeled one?

 

[tirediron]

Probably about $10. Seriously, the use of the word "digital" is nothing more than a marketing ploy. If you're buying a filter, especially a CPL, make sure you spend a little extra and get a good one. Lee, Singh-Ray, B+W and Heliopan are the best names. Hoya, Tiffen and Cokin are decent, consumer brands.

 

[fmw]

It took a while to understand what a CPL is. No there is no difference between two circular polarizers because one is labeled digital. There can be a difference in quality, of course, but the term digital wouldn't describe that. It would be a marketing term used to attract digital photographers.

 

[petrochemist]

I think I remember reading some marketing bumf on filters that claimed their 'digital' ones had improved coatings.
Certainly I've never noticed any issues using older CPLs.

 

[pgriz]

You have to pay for the "digital" one with digital currency.

Joking aside, there was a difference between polarizing filters in that some were linearly polarized, and some were circularly polarized. The linearly-polarized ones didn't work well with auto-focus systems. As far as I know, pretty much all polarized filters are now of the circularly-polarized variety.

As for marketing terms, I'm waiting for them to say they are gluten-free, zero fat, and carb-free. Heck, while we're at it, how about "assembled by organically-fed workers"?

 

[KmH]

SLR's that don't have auto focus (AF) or through-the-lens (TTL) metering can use a single glass element linear polarizing filter.

SLR's & DSLRs that do have auto focus and/or through-the-lens metering require a circular polarizing filter.

A CPL has a single glass element linear polarizing filter, and a 2nd, adjustable glass element that in effect blocks linearly polarized light so the AF and TTL systems in the cameras can function properly.

So you can use a linear polarizing filter on a DSLR camera as long as you don't care that you have to manual focus and meter the light .

 

[Solarflare]

Glas is never ever digital, but yes you need circular polarization filters.

 

[TCampbell]

CPL or referring to it as a "digital" polarizer may be referring to the auto-focus and metering issue.

With a manually focused and metered camera, you can use a "linear polarizer" (sometimes called a "top polarizer").

With a camera that uses phase-detect auto-focus and has built-in metering, a standard linear polarizer can make it extremely difficult for the focus or metering to work correctly.

These cameras require something called a "Circular polarizer" (CPL). The circular polarizer is really just a dual layer filter... one layer has the standard linear polarizer just like any other linear polarizer, but it adds a second layer called a quarter-wave plate which alters the polarity of the lightwaves into a circular pattern (hence the name "circular polarizer"). This added layer (the quarter-wave plate) allows the auto-focus and metering to function as desired.

Other than making sure you actually do have a circular polarizer, it's nice if it has anti-reflective coatings to reduce ghosting (reflections).

 

[table1349]

The only thing that I have ever heard that makes a "Digital" CPL different from a CPL is that the "Digital" Model does not have a UV haze layer in the coatings. Not sure if it true and frankly it doesn't really matter.

 

[unpopular]

My digital CPL had this cool blue-yellow color shift as you rotated it! Added that highly sought after unpredictable pizzaz to my photography.

 

[TCampbell]

My digital CPL had this cool blue-yellow color shift as you rotated it! Added that highly sought after unpredictable pizzaz to my photography.

Any CPL should create a gold/violet color shift if you look through it "backwards". There is actually a real front vs. back on these filters and what happens to the light is different depending on which direction it passes through.

 

[unpopular]

My digital CPL had this cool blue-yellow color shift as you rotated it! Added that highly sought after unpredictable pizzaz to my photography.

Any CPL should create a gold/violet color shift if you look through it "backwards". There is actually a real front vs. back on these filters and what happens to the light is different depending on which direction it passes through.

No way! So they installed the filter incorrectly at the factory?!