Polarizing filter not working - Sony Cybershot DSC-HX1

Ok this is weird, will appreciate any info or suggestions.

 

I have two polarizing filters that do work pretty fine. I have tested them with my cameras and smartphones. So, if I take shots at windows or flat surfaces producing reflections, the use of those filters removes them given they are rotated to the right angle. Nice, no problem. Polarizing filters work one way and not the other, meaning you have to put then on the camera on some specific direction, otherwise it will not work.

 

Well, the big filter doesn't do anything on my Cybershot DSC-HX1. It does it's magic on EVERY other device with a camera except the Sony Cybershot. Already tried using it backwards and nothing happens. That's weird, never seen anything like it.

 

I disassembled a small calculator to remove the polarizing film in order to perform some tests, it's a little bit dark but it works. So this filter does work on EVERY device, including the Sony DSC-HX1. How can this camera be immune to the CPL filter built for cameras? I don't get it.

 

Today I will visit some stores to see if I can find CPL filters that they let me actually TRY on that camera. Sadly in my region stores with that kind of filters are very rare and difficult to find. If anyone could contribute with an explanation I will appreciate it. Already searched the web but found no clue on why this is happening.

Some cameras have a quarter-wave bi-refringent plate over the sensor as an AA (anti-aliasing) filter. The Nikon D800 was one such. This type of filter material is the same that's used in circular polarising filters to 're-scramble' the light after passing through the linear polarising membrane. That's why CPLs only work one way round.

 

(When used backwards, the bi-refringent element removes any natural light polarisation, such that the polarising membrane has no polarised light to block, and therefore has no effect.)

 

So what I think is happening, is that the material used as an AA filter over the camera's sensor is somehow neutralising the effect of a CPL. It shouldn't be able to do this with a 'linear' polariser however.

 

I suggest you seek out an 'old-fashioned' linear or non-circular polarising filter. The membrane out of an LCD display is such a thing.

 

FWIW, I think the scaremongering rumours used to get people to buy circular polarisers, and scrap all their old linear ones when AF was introduced, was all hype and BS. That's probably, what, 35 years ago now? And of course today the CPL has completely replaced the old 'linear' polarising filters that used to be common, but they're still out there by the junk-box load, if you look for them.

 

The real joke is that; in reality the only real polariser is a linear type, and the CPL just adds a scrambling, de-polarising element on the back end. Which is why a CPL only works one way round.

 

A 'circular' polariser does work with a Nikon D800 BTW, but the D800 uses a double bi-refringent element in its AA filter. So I suspect your Cybershot uses a slightly different AA filter configuration. One that screws up the action of a CPL in some way.

Edited February 8, 2020 by rodeo_joe|1

I thought about this some more, and can't figure out how anything other than another polariser, internal to the camera, would prevent a CPL from working.

 

I know for a fact that some bridge cameras don't use a proper variable aperture. Instead they use a neutral density filter in the lens, which is flicked in or out to simulate a change of aperture. You can usually tell such 'fake' apertures by putting the camera into Aperture Priority mode and seeing if you get only a choice of two apertures, and if the depth-of-field shows no sign of changing between those apertures.

 

I suppose its possible that a polariser, or pair of polarisers, was used in place of a neutral-density filter for such an aperture simulator.

 

Clutching at straws here, but it's an interesting and intriguing phenomenon.

Definitely interesting. I also was a bit skeptical about the need for CPLs and never found any problem with my old D200 and old regular polarizers. No doubt they can mess up metering or focus or something on some cameras, but the problem might not be as bad as people think.

Well, the big filter doesn't do anything on my Cybershot DSC-HX1. It does it's magic on EVERY other device with a camera except the Sony Cybershot. Already tried using it backwards and nothing happens. That's weird, never seen anything like it.

 

Hi, I have a really, really hard time believing this really happens. In my experience the usual thing when someone thinks their polarizer "doesn't work" is that they don't clearly understand the photographic "conditions" in play, so are mistaken about where it SHOULD work.

 

Here's a test I occasionally suggest to people to "test" their polarizer. If you have a flat screen (LCD) monitor, point your camera at it and rotate the polarizer. If you can make the screen black-out completely this proves that the polarizer is working.

 

Or hold a second polarizer in front of the first, then rotate one of the polarizer. Again, the ability to black-out proves that both polarizers are working. There is an issue when using two polarizers, however, if a circular polarizer is involved. The side with the "quarter-wave plate" is not allowed to face the other polarizer; this cancels one of the polarizer effects and they won't be able to black-out. So you have to be careful doing this test. As a note, the quarter-wave plate is on the side of a polarizing filter that normally faces the camera.

Thank you all for the comments, I'm updating the thread with some results. The problem has been solved. As we can see on YT (some examples), some CPL work better than others, this one had weak effects regarding the Sony Camera, but the other (smaller) polarizing filter was working pretty well (but has diff diameter, that's why I couldn't keep using that one). Besides this particular CPL not being as strong (effective), there was an issue with the simple rotation of the lens inside the filter, that was it, as simple as that. I was scratching my head because there was a place where "it worked" at night around 30% of how it should work but it didn't work the same the next day (angle was different). It wasn't noticeable until I tried rotating the filter having the camera in front of me while having a fingerprint reflection barely rotating. Disassembled the filter, cleaned, etc put everything together again, free rotation now.

 

Anyway... (in general) as mentioned there are some filters that don't show as strong effects as others. It's shown here:

and even if that filter was backwards (sounds to me as if is), there is one comment stating lack of effects with another filter and camera. (The Vivitar comment), not being able to completely block the polarized light failing the test.

 

Some cameras have a quarter-wave bi-refringent...

I was curious about something like that (but I didn't know as much as you about the topic), all I knew is some materials like cellophane can have effects on light altering the polarization, but that doesn't mean if used directly it would polarize light having the same effect as a polarizing filter. I played around with that in the past when I read the news about it. Your comment was very informative. Thanks.

 

I thought about this some more, and can't figure out how anything other than another polariser, internal to the camera, would prevent a CPL from working.

The following is not exactly related to what caused the issue here but, as a bonus there is an interesting effect using 3 polarizing filters. Supposedly, one filter would cancel the light in some directions allowing only one, and then the second filter would cancel the other angle leaving a black result, yes, but when a third polarizing filter is used... something strange happens. This explanation of Polarizing filters and the Bell's Theorem is quite interesting:

 

Definitely interesting. I also was a bit skeptical about the need for CPLs and never found any problem with my old D200 and old regular polarizers. No doubt they can mess up metering or focus or something on some cameras, but the problem might not be as bad as people think.

Nice, in my case I never imagined some would not be as effective as others (quality), or facing a rotation problem as I did, simple, easy to solve, but confusing until I realized what was happening. Regarding CPL, I never used them in the past due to a wide variety of reasons, but at some point faced situations when removing reflections was actually desirable.

 

Hi, I have a really, really hard time believing this really happens. In my experience the usual thing when someone thinks their polarizer "doesn't work" is that they don't clearly understand the photographic "conditions" in play, so are mistaken about where it SHOULD work.

 

Here's a test I occasionally suggest to people to "test" their polarizer. If you have a flat screen (LCD) monitor, point your camera at it and rotate the polarizer. If you can make the screen black-out completely this proves that the polarizer is working.

 

Or hold a second polarizer in front of the first, then rotate one of the polarizer. Again, the ability to black-out proves that both polarizers are working. There is an issue when using two polarizers, however, if a circular polarizer is involved. The side with the "quarter-wave plate" is not allowed to face the other polarizer; this cancels one of the polarizer effects and they won't be able to black-out. So you have to be careful doing this test. As a note, the quarter-wave plate is on the side of a polarizing filter that normally faces the camera.

Yes, but solved, posted above. About the polarizing experiments, as mentioned there are very interesting effects depending different materials, the posted videos might bring some interesting light to the matter.

 

At the end of the day: the filter was fixed, now rotating, working fine. Thanks for the help.

The bozo in the video holds the larger CPL filter the wrong way round in the first 'demonstration'!

 

I think he corrects it later, but why not edit out the false start?

 

Youtube videos - about as reliable as a bus timetable.

The bozo in the video holds the larger CPL filter the wrong way round in the first 'demonstration'!

 

I think he corrects it later, but why not edit out the false start?

 

Youtube videos - about as reliable as a bus timetable.

Yes, but I pointed out the Vivitar comment regarding that YT vid. Not every CPL works the same way (price, quality). Some comparisons are available on the web.

 

To me, the ones that work best, fully polarizing... are those coming from LCD screens (B/W) and then the ones from color screens such as laptops or tablets. I have extracted some in the past (electronics hobbies and projects), those filters need to block light effectively to provide full black on the screen. Some are not so powerful leaving weak black or some sort of dark gray. The problem with those things, to create custom polarizing filters is the glue. When removing the layer, it ends covered with sticky surface and blurry, very blurry loosing the transparency it used to have. Some methods to extract those filters work better than others but damage the layer, the one preserving it keeps more glue. At the moment haven't found any product in my area that works perfectly at removing it. Some other polarizing options such as glasses (I have tried) do not block all the light but it's more due to the price/quality.

 

I've played around with several options because in my country... polarizing filters are at the moment very rare if not impossible to find. The store where bought this one had only two, in two separate cities. It's impossible to find polarizing sheets to play around, buying online works but increases the price and I'm not very good at waiting 2 weeks for that. Sometimes when I travel I do bring a list of stuff to buy. Sadly photo gear stores changed a lot in my country in recent years, the one keeping a bit of specialized stuff in this angle is Nikon but terrible website you never know what they have and the sellers have little training, and the prices are high.

 

In the past when film was the thing you could find lots of brands and variety of filters on almost every photographic store. Those were good days.