polarizing filter for Q3 - circular or linear?

[Paul W]

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Hi all, 

I understand that mirrorless cameras do not need a circular polarizer (rather than linear) as much as DSLRs did. My question is whether on a Q3, a circular polarizer is more useful than a linear polarizer - because the strength of the effect can be varied by rotating?

Thank you for your thoughts.

[PhotoCruiser]

Not sure what effect you write of, exaggerating colors or removing reflections.

Mirrorless camera can make use of a polarizer, to remove reflections, or are i'm wrong?
I had always circular ones and turning them make the reflections disappear or stronger.

Chris

[Paul W]

Thank you Chris. Yes, I am asking whether the ability of a circular polarizer to vary the amount of reflection removal, and colour deepening by rotating its ring (a second polarizer?), makes it better/more useful than a linear polarizer - which I understand cannot vary the amount of reflection or colour deepening, because it has no ring (second polarizer)? 

Paul

[Bikie John]

I'm not sure, but I think the reason some SLRs needed circular rather than linear polarisers was because part of the system used a non-metallic mirror. Mainly for metering, I think. Light from a linear polarising filter is polarised (surprise!). Reflecting from a non-metallic surface also polarises light, so the two could come into conflict.

A linear polarising filter is a single functional layer which does what it says on the label. It filters the light polarised in one direction more than it does others, which is how it can reduce reflections, darken skies, and intensify colours. The light coming out is polarised. A circular polariser has two layers. The first is a linear polariser, so it can do all the things that a linear polariser does. The second layer in effect "scrambles" the polarised light from the first layer, so the light coming out is not polarised. I think the technical term for it is a "quarter-wave retarder". The combination means that a circular polariser will have the same optical effects as a linear one, but the light coming out is not polarised so it doesn't have problems with non-metallic mirrors.

All of which means that - in theory! - you can use linear or circular polarisers equally well on mirrorless cameras. Caveat is that I haven't put it to the test.

John

Edited August 20 by Bikie John
Adding detail

[Alexander108]

vor 18 Minuten schrieb PhotoCruiser:

Not sure what effect you write of, exaggerating colors or removing reflections.

Mirrorless camera can make use of a polarizer, to remove reflections, or are i'm wrong?
I had always circular ones and turning them make the reflections disappear or stronger.

Chris

Any camera can make use of a polarizer. Polarizer have been used in the film days, SLR, Rangefinder, DSLR.  They remove reflections. You can see through water but also clouds and blue sky is clearer.

The linear polarizer is just not suited for digital cameras, including DSLRs. This is what you find on the B&H website: A linear polarizer differs from a circular polarizer in that it does not support the use of a camera's autofocus or auto exposure functions; it is best suited for use with manual cameras, such as view cameras, that are not dependent on internal mechanisms to determine focus or metering settings.

As far as I know you cannot make reflections stronger. By turning the CPL it goes from neutral (no change) to maximum. It is not always desirable to remove all reflections. 

To the initial question. Here's a good overview: https://kasefilters.eu/blog/circular-vs-linear-polarizing-filter

 

Edited August 20 by Alexander108
Typo

[Bikie John]

1 minute ago, Alexander108 said:

Any camera can make use of a polarizer. Polarizer have been used in the film days, SLR, Rangefinder, DSLR.  They remove reflections. You can see through water but also clouds and blue sky is clearer.

The linear polarizer is just not suited for digital cameras, including DSLRs. This is what you find on the B&H website: A linear polarizer differs from a circular polarizer in that it does not support the use of a camera's autofocus or auto exposure functions; it is best suited for use with manual cameras, such as view cameras, that are not dependent on internal mechanisms to determine focus or metering settings.

As far as I know you cannot make reflections stronger. By turning the CPL it goes from neutral (no change) to maximum. It us not always desirable to remove all reflections. 

To the initial question. Here's a good overview: https://kasefilters.eu/blog/circular-vs-linear-polarizing-filter

 

That is interesting, I hadn't heard that. I wonder what the rationale is.

John

[Alexander108]

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vor 1 Minute schrieb Bikie John:

That is interesting, I hadn't heard that. I wonder what the rationale is.

John

Physics way beyond a level that I am capable of 🤣

[Bikie John]

16 minutes ago, Paul W said:

Thank you Chris. Yes, I am asking whether the ability of a circular polarizer to vary the amount of reflection removal, and colour deepening by rotating its ring (a second polarizer?), makes it better/more useful than a linear polarizer - which I understand cannot vary the amount of reflection or colour deepening, because it has no ring (second polarizer)? 

Paul

I'm not sure if you have a misunderstanding here, Paul. All polarising filters, whether linear or circular, have a ring so that you can rotate them when they are mounted on the lens. You need to do this because the direction of polarisation of the light is "random". Not random at all, it depends on the circumstances, but it varies all round the clock depending on the source.

Once upon a time all polarisers were linear. Then we discovered that the design of some SLR cameras had problems with this, so the more complex circular polarisers came out. I haven´t looked, but I suspect that it might be hard to find a linear polarising filter these days,.

Hope this is helpful ... John

[Alexander108]

Maybe to add some additional ideas / thoughts.

• Wide angle lenses in combination with a vast landscape with a lot of blue sky can result in uneven blue distribution as the polarization effect depends on the angle to the sun. Often with wide angle lenses you see brighter areas to the sides of the frame. Maybe not that much on the 28mm of the Q3. 
• As the polarizing effect depends on the angle of the sun (on bright days) you want to have the sun ideally 90° to the frame (on the sides). That maximizes the effect. With the sun behind you there is very little effect.
• The polarizer is not only for reflections and blue sky. It is great in nature. Leaves or grass have moisture on them that reflects light and makes them a bit pale. With a polarizer you get these wonderful deep greens.

So, for the Q3 you need a CPL. I use the PolarPro - MagFlip Hood that allows easy access to the filter in combinations with K&F magnetic filters as I also use ND filters with my Q3 to reduce shutter speed in bright daylight for some motion blur.

[PhotoCruiser]

vor 38 Minuten schrieb Alexander108:

As far as I know you cannot make reflections stronger. By turning the CPL it goes from neutral (no change) to maximum. It is not always desirable to remove all reflections. 

First Thanks Alexander!

Yes i know that porarizer filters work on all cameras, thats why i wondered about the mirrorless OP mentioned.

I may explained wrong, a polarizer can not make reflections stronger, i meant that from full to much less or none.
I used rarely polarizers on film cameras either to remove reflections or to make sky more pop but from when i use digital cameras i never use them for color as i do it when editing and rarely for reflection removal if needed. I often use reflections as part of the composition like the one below for example, but thats my taste.

Chris

 

 

 

 

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[Paul W]

Thank you all.

It seems I still have much to learn. From my time with dSLRs I have a memory of rotating a ring to vary the amount of polarization, from maximal to nil. Currently with a Q3, I have both a circular polarizing filter and a linear polarizing filter. Both are magnetic (from Maven filters). Neither has a ring. Yet both rotate, and both vary the amount of polarization as they rotate. I suspect that this rotation is because they are magnetic, and not threaded. I will need to test both to see which I prefer. 

Once again, thank you all.

 

Paul

 

[Alexander108]

vor einer Stunde schrieb Paul W:

Thank you all.

It seems I still have much to learn. From my time with dSLRs I have a memory of rotating a ring to vary the amount of polarization, from maximal to nil. Currently with a Q3, I have both a circular polarizing filter and a linear polarizing filter. Both are magnetic (from Maven filters). Neither has a ring. Yet both rotate, and both vary the amount of polarization as they rotate. I suspect that this rotation is because they are magnetic, and not threaded. I will need to test both to see which I prefer. 

Once again, thank you all.

 

Paul

 

Yes, the ring is only necessary as it is screwed on the filter thread, yet it needs to turn. In the magnetic version the magnetic ring is threaded to the lens and the "filter glass" can freely rotate as it us held by the magnets. It's the same. It needs to rotate as you rightly said. In the meantime I also prefer the magnetic system.

[fotografr]

I use Breakthrough Circular Polarizers on both my D-Lux 8 and Q43. I painted a small line on the edge of the polarizer to mark the point where I get maximum effect. On the Q43, the Breakthrough filter accomplishes a secondary effect, which is to complete the water resistance by sealing the end of the lens. The filters aren't cheap, but they are very effective.

[masjah]

The artistic effect of a polariser, that is to say enhancing contrast, cutting out reflections, or whatever, is EXACTLY the same, whether it's a linear or a circular polariser. Both rotate in the same way in order to vary the effect. They both cut out light waves vibrating at ninety degrees to the direction of polarisation. [The terminology is even more confusing because the term "circular polarisation" is also used in electromagnetic theory to denote a different particular kind of wave motion, but that's another story.]

The problems arose firstly with film SLRs because the mirror introduced a polarisation of its own, so that, in conjunction with a linear polarising filter, it messed up the metering to an unpredictable degree.

The way to think of a circular polariser (and I'm saying it's just a way to think about it, it's not exactly quite what happens) is as follows: Imagine a simple linear polariser with some sort of depolarising device stacked right behind it. The light comes in through the polarising layer, and the unwanted light gets cut out - unwanted reflections from water, scattering in the sky, whatever. But once it's gone, it's gone, and the desired artistic effect is reduced. But having done this, the light then gets depolarised, so there is no longer any favoured direction so the metering or whatever no longer gets messed up.

You can experiment with two circular polarisers. If you arrange them so that their front faces are facing each other, then you will find that you can cut out virtually all the light by "crossing" them, so that one cut out one plane of light waves, and the other cuts out the plane at ninety degrees, thereby cutting out all the light. Now turn them round so that the INNER faces are adjacent. You will find that "crossing" no longer works [I'll leave you to work out why!]

The simplest thing, as has already been implied above, is to forget all about linear polarisers.

 

[bobtodrick]

We haven't stocked linear polarizers for years.

Most of our suppliers (including B+W) don't have linear in their cataloque.

[masjah]

Oops - missed a wrong "autocorect" in my post above.  In line 8, 'reduced' should read 'produced'.

 

[ckern]

In my experience, circular polarizers are more effective in darkening skies or water than in removing reflections from glass.  And while I haven't performed any rigorous tests, I suspect using a circular polarizer when shooting through, say, a plate-glass window may interfere with the subsequent use of Lightroom's reflection-removal tool in post, if that's what you plan on doing; i.e., eliminating some of the reflection with the polarizer may make it more difficult for the Adobe neural network to disentangle the reflection from the subject behind it.  With a static subject like a storefront display, I would be inclined to shoot the image twice—once with the polarizer and a second time without it—then try AI reflection removal on both captures to see which works best.