[Docrwm]

It is my understanding that the problem with linear polarizers has nothing to do with the sensor - it is the focusing system and or metering system that gets in trouble with linear polarizers since they often rely on semi-silvered translucent mirrors that siphon off some light. I have found many many references to CDAF and DFD based mirrorless systems using Linear Polarizers without problems. I am not certain if PDAF on chip sensors are negatively impacted. In any case it is also true that even full blown Linear polarizers don't seem to interfere with most newer DSLR's - this may be a problem that was huge when first introduced but over time became a non-issue or one where conventional wisdom prevailed over actual fact. Theory says you could have a problem, but it is hard to find evidence of the problem in actual use.

Perhaps you are right and I am out of date, however having had personal experience with old Linear Polarizers causing problems I'll stick with CPLs.

[UncleVanya]

Perhaps you are right and I am out of date, however having had personal experience with old Linear Polarizers causing problems I'll stick with CPLs.

I would not go out of my way to change either - LOL. I just think we may all have been conditioned to accept it and the few times I have tried it they have worked fine. Certainly no issues on mirrorless CDAF bodies that I did this on.

[Docrwm]

I would not go out of my way to change either - LOL. I just think we may all have been conditioned to accept it and the few times I have tried it they have worked fine. Certainly no issues on mirrorless CDAF bodies that I did this on.

That's good to know, perhaps it works on the K-01 too but it certainly messed up both my K-x and K-r back in the day. So, no Linears for me.

[wings]

Good discussion - thanks. I'm refreshing my knowledge after a hiatus.


One point I did NOT see is that the OP was talking about film experience and filters and most pointed out the utility of polarizers (which I agree with) but NOT that the old PL filters are BAD on dSLRs and that it needs to be a Circular Polarizer (CPL) to not cause artifacts with the digital sensors.

I did not know that, Thanks.

---------- Post added 10-26-18 at 08:55 PM ----------

That's good to know, perhaps it works on the K-01 too but it certainly messed up both my K-x and K-r back in the day. So, no Linears for me.

I was wondering if the quality of the linear filter would make a difference concerning this issue?

[clickclick]

I was wondering if the quality of the linear filter would make a difference concerning this issue?

No, think it's a thing of physics and how light works versus quality of materials in the filter.

[wings]

No, think it's a thing of physics and how light works versus quality of materials in the filter.

Thanks for your answer, always welcome. I understand that somewhat, perhaps because of a high tech background in me, but probably not to the degree that some of you do. I suppose that I was trying to find out why some seemed to indicate why the Linear Filter did not interfere with the sensor etc. It is pretty clear though that CPL should be the one to use if you choose to use a polarizing filter. But, I would be interested in knowing just how much of a difference the quality of filters make? Is it worth the expense? Now I know that a professional photographer would want and probably use only the best filters, but wondered what the differences would be if the same scene were imaged with a cheap vs not so cheap polarizing filter, or any filter for that matter?

[Docrwm]

Thanks for your answer, always welcome. I understand that somewhat, perhaps because of a high tech background in me, but probably not to the degree that some of you do. I suppose that I was trying to find out why some seemed to indicate why the Linear Filter did not interfere with the sensor etc. It is pretty clear though that CPL should be the one to use if you choose to use a polarizing filter. But, I would be interested in knowing just how much of a difference the quality of filters make? Is it worth the expense? Now I know that a professional photographer would want and probably use only the best filters, but wondered what the differences would be if the same scene were imaged with a cheap vs not so cheap polarizing filter, or any filter for that matter?

I know this is an old article but I think the main points still hold true on quality and issues related to cheap filters.
UV filters test - Introduction - LensTip.com

Here's a newer one CPL filters:
Polarizing filters test 2015 - Introduction - LensTip.com

[clickclick]

but wondered what the differences would be if the same scene were imaged with a cheap vs not so cheap polarizing filter, or any filter for that matter?

Having a quality filter is key. I would say if you're not willing to shell out the bucks for a top notch filter like a B+W, then don't use one unless you are willing to sacrifice image quality. The polarizer is one of the few filters you can't really duplicate in post processing. The key is the polarizer is impacting reflections. Think of water. By reducing the reflections on the surface, you can see down in to it. You can't remove that reflection to reveal what's in the water in post processing. Same with leaves, clouds etc., The reflections are changing what's coming through the lens in a way you can't adjust for. It affects saturation, hue, contrast and more. If you missed them, check out the articles in my earlier post here:

Use of filters and their need and affects on modern DSLRs - Page 3 - PentaxForums.com

[Des]

One thing that hasn't been mentioned is whether HD lens coatings have reduced the need for a C-PL. I've got two HD lenses (DA 20-40 Ltd and DA 55-300 PLM) and the coatings do seem to cut down glare quite a lot. Of course they won't "cut through" a reflective surface like a C-PL can but my feeling is that I would not feel as compelled to use a C-PL in glary conditions as I would with smc lenses.

[jbondo]

I know that everyone has their own unique approach to thinking about how to shoot and I respect that! That's what makes us all individuals.

My particular way of doing things is to break things down in to steps and consider each step in the order they occur. It's not 'right' or 'wrong' per se. It does bring a great deal of clarity to my thinking about what I am doing and helps me make more effective decisions about adjustments.

One thing that hasn't been mentioned is whether HD lens coatings have reduced the need for a C-PL.

There are two scenarios here:
1. C-PL is in front of lens

If we expand upon UncleVanya's previous post:

Sensor | Color Filter Array (CFA) | Light < --------

We get:
Sensor | Color Filter Array (CFA) | Lens | C-PL | Light < --------

in this case It's all about what I want to do with the light before it enters my lens - and therefore my use of a C-Pl has no relationship with which lens I am using. I'm already done with thinking about what I want to do with the polarization aspects of the light before I ever start thinking about what I want to do with the lens. The reason for this is because this is the order in which these things occur. I keep them separate.





2. C-PL is behind one or more surfaces with HD coatings (drop-in filter)

Sensor | Color Filter Array (CFA) | C-PL | Lens | Light < --------

In this case the subcomponent of the light that is scattered internally as it passes through the lens may not have the same polarization state. Therefore the C-PL may have reduced modifying capability.



Even though my working style is essentially the same in both scenarios, my mental model is quite different. I think about what the C-PL is doing when it does it.


Now, with all of the above being said, there is a reverse case to consider:
Q: Is there a case when the lack of HD coatings contradict the use of a C-PL?
A: Yes. In extreme contrast situations (high illuminance) especially if both the lens and the C-PL do not have excellent coatings, you can get a lot of internal reflection between the front element and the filter so you're better off not using the filter.

[Des]

Another thoughtful and interesting post @jbondo

[wings]

Beyond mechanical wear, do sensors or filters degrade over time?

[newmikey]

Beyond mechanical wear, do sensors or filters degrade over time?

Everything degrades over time, the question is how much time. I'd venture to say the sensor will probably outlive the shutter by far and thus the workable life of the camera in most cases as it's normally not very exposed. Filters will deteriorate from cleaning and exposure to outside conditions much faster. I wouldn't use a filter once I can discern microscratches or abrasions from even the most careful of cleaning after say, a year or three, four but that's a rough guesstimate.