selmslie Loc: Fernandina Beach, FL, USA

I tried the test with an old filter I once used for film before there were any circular polarizers for digital. I got the same result, front to back matters there too.

I think that the difference has more to do with whether there is a mirror in the camera. The effect looks different when you look directly through the filter like the film or sensor does rather than through the viewfinder of an SLR or DSLR.

User ID

Dead wrong about front vs back. What you wrote happens to be true of linear but not of circular polarizers.

Nearly every Hawgster has a CPL. Assuming you have one, it easy enough to just see for yourself.

IDguy Loc: Idaho

I’ll give that a try.

My initial reaction was that front to back orientation makes no difference. Can you explain why or how it can matter?

EDIT: Ok, did a little research. Found my initial thought was correct for linear polarizers such as lens filters of old or sunglasses. Today’s camera filters are called CP or circular polarizers for reasons not important here. They are actually two different filters in sequence. The effect on light differs due to which filter it passes through first. So your point is correct for CPs.

User ID

It has already been explained in a recent thread and in many threads before that.

Basical the front polarized and the back depolarizes. You that done in the correct order or else you get no effect.

Spirit Vision Photography Loc: Behind a Camera.

Was it by any chance purchased from E-bay or Amazon? If so, they very well could be cheap Chinese counterfeits. The market is fraught with them. 😡

selmslie Loc: Fernandina Beach, FL, USA

Maybe I don't really have a circular polarizer to test with. I have hardly used a polarizer for decades.

I tried the test on my A7 II. The front to back orientation matters with the linear polarizer. It works as intended in the normal direction.

With the filter flipped over there is no effect at all but the sensor I used has no Bayer array so no blue/yellow shift.

Next I tried the linear filter with an unmodified Df. Same results, flipping matters.

The reason for the introduction of circular polarizers may have more to do with the effect of the linear polarizer on the SLR/DSLR metering or autofocus operation.

For circular polarizers, see this article, "In 'circular' polarizing filters, the polarizing effect works when the scene is viewed from the male threaded (back) side of the filter, but does not work [as intended] when looking through it backwards."

fetzler Loc: North West PA

Indeed CPL filters are directional. They have a front and a back side. Only light passing from the front side to the rear has the desired polarizing effect.

DRM Loc: NC

I have several B&W circular polarizers; they're excellent. Fortunately for me, I haven't experienced the failure you describe here, and I wouldn't hesitate to purchase B&W products again. I would also recommend filters by Breakthrough Photography--quality equal to B&W, with certain design features (knurled edges, color coded, etc.) which make them even easier to use. And, they come with a 25-year warranty.

selmslie Loc: Fernandina Beach, FL, USA

Correction. The only two polarizers I have been looking at are circular. I can't find my old linear polarizers.

User ID

Either your post lacks some much needed proof reading or your PLs are not properly marked ... or maybe both :-(
Youre usually very scientific and so that post really surprises me (not sarcasm).

selmslie Loc: Fernandina Beach, FL, USA

They were marked correctly but I wasn’t wearing my readers.

I have bad memories of using a polarizer with Kodachrome 25 (1980). I ended up with darkened skies and water surfaces but only one of the images came close to looking real.

richardsaccount

Some years ago I had a couple of B+W CPL filters. Eventualy the polarizing filter material that was
sandwiched between the glass faded. I'm not dittzing B+W, but I switched to Hoya and Tiffen.
I've had no problems. I don't use filters that much anyway. In my case it probably doesn't matter.

E.L.. Shapiro Loc: Ottawa, Ontario Canada

WOW! Stop fighting!

The first time I used a CIRCULAR polarizing filter I immediately observed that front-back orientation is indeed an issue. This has nothing to do with the effect of rotating the filter except for the fact that if the glass is replaced backward, rotating the filter will not work properly is to its polarizing effect.

Of course, the mounting threads are only on one side of the filter frame but if the glass accidentally comes out of the frame and if the glass is reversed upon replacement it will not work correctly.

The test where you observe the effect with a flat monitor screen is valid. It involves cross-polarization and the reverse orientation will impart a bluish tint on the whites and fail to completely black out. The black-out effect is an indication of complete cross-polarization.
should be reinstalled and held in place by the threaded-notched relating ring or the spring-meal wire, if they can be found. A replacement part might be available from the manufacturer or distributor. If you have lots of filters and lenses, a lens spanner wrench is a good investment. It can be safely used to tighten those notched retaining rings- about $20 from Amazon and others.

Unless you have the dexterity, skills, and tools of a watchmaker, I would not advise using GLUE anywhere on or near a filter or lens. In the case of a CPL filter, the glue would likely migrate and jam the rotating
ring. In the olden days, mechanical watch repair technicians use special watch-crystal cement to secure the transparent cover (the crystal) on wristwatches and pocket watches. It was like neurosurgery! I know- my grandfather was a watch and clockmaker and unfortunately, I did not inherit his skill and extreme patience.

I have no experience with outsourced filter repair but companies such as B+W would likely be able to repair their filters or supply parts. B and H have a good reputation for customer service- contact them, and they will advise you on what they can or can't do.

Lots of repair issues can be addressed with professional repair sources or workarounds and DYI fixes. Some of these homespun remedies are better, safer, and more effective than others. Whatever the case may be, I will never understand why folks can simply say or write "I respectfully disagree with... whatever" rather than lash out with harsh demeaning statements. It's an insult to the person to whom it is directed and it insults the intelligence of everyone who is reading on. The infighting just muddies the waters and distracts from the real issue at hand- it is of no help to the OP. Most folks are intelligent enough to weigh opposing opinions on most subjects and make up their own mind. Admittedly, I will write a "DON'T DO DAT" kind of response if I feel someone is about to destroy an expensive piece of gear or worse, hurt themselves.

kymarto Loc: Portland OR and Milan Italy

If it's linear it doesn't matter. If circular hold it up to you eye and rotate (your eye acts as the lens. If all you see is a slight blue/yellow color shift, reverse it.

JD750 Loc: SoCal

wow! Well You do say you don’t use them much.

I have had the exact opposite experience which is Tiffany and Hoya are low quality cheap filters and they exhibit aberrations, flares etc, whereas B+W are high quality products, considerably more expensive, and the company stands behind their products. Just saying.

But it’s your camera bag so use the filters you like.