Polarizing Filters

manual_focus wrote:

Still haven't decided which way I'll go.

I always leave my Hoya Fusion antistatic on my lenses, because contrast is enhanced.

manual_focus wrote:

One additional note is that while the camera settings were the same, the shutter speed was two full stops difference (1/1600 sec vs 1/400 sec) without and with the filter. The CPL is removing a lot of polarized light which accounts for the differences

CPL's darken the light from an image. Due to their nature, they darken polarised light more than non-polarised light.

You need to take this into account when you use CPL filters. Your shots with the filter look under-exposed to me.

I'm will Peter on this one. I used to slap a polarizer on quite a bit but, I find 'em to make the sky unnaturally dark. With software, one can tweak that in a bit if necessary anyway. I find them more useful in adjusting the reflections on water. I have a couple of different CPLs and they're a lot different in the variance of effect and how subtly you can apply it. Thanks for posting it, Manual.

I would say that such a polarizer filter makes sense to use on the sky with clouds only. And to remove reflections of course.

kypfer wrote:

Just remember you don't need to use the polariser at "full" setting, often a "half-way there" can give a pleasing contrast without "over-cooking" it … well worth taking two or three shots at slightly differing degrees of filtration then assessing the results when you get home. Just make a few notes as you go, the filter settings aren't recorded in EXIF

Something to work at as I can easily tell when the filter is at full polarization, but not so much as to a what point is it best.

Good advice, Thanks.

Nice clouds.

Excellent examples, Polarizers although not necessary all the time are an excellent and useful tool in photography. I'd suggest worth having in anyone's kit.

PeterPentax wrote:

manual_focus wrote:

One additional note is that while the camera settings were the same, the shutter speed was two full stops difference (1/1600 sec vs 1/400 sec) without and with the filter. The CPL is removing a lot of polarized light which accounts for the differences

CPL's darken the light from an image. Due to their nature, they darken polarised light more than non-polarised light.

You need to take this into account when you use CPL filters. Your shots with the filter look under-exposed to me.

Yes, the CPL reduces the amount of light getting to the sensor because it is not clear glass and because it blocks light of a particular polarization. With my CPL I needed to increase the amount of light to the sensor by four fold (2 stops). Your description of a CPL may need some more thought. See: https://en.wikipedia.org/wiki/Polarizer#Circular_polarizers

Interesting as to your comment that the filtered images (on the left) look under-exposed.

manual_focus wrote:

PeterPentax wrote:

manual_focus wrote:

One additional note is that while the camera settings were the same, the shutter speed was two full stops difference (1/1600 sec vs 1/400 sec) without and with the filter. The CPL is removing a lot of polarized light which accounts for the differences

CPL's darken the light from an image. Due to their nature, they darken polarised light more than non-polarised light.

You need to take this into account when you use CPL filters. Your shots with the filter look under-exposed to me.

Yes, the CPL reduces the amount of light getting to the sensor because it is not clear glass and because it blocks light of a particular polarization. With my CPL I needed to increase the amount of light to the sensor by four fold (2 stops). Your description of a CPL may need some more thought. See: https://en.wikipedia.org/wiki/Polarizer#Circular_polarizers

Interesting as to your comment that the filtered images (on the left) look under-exposed.

I disagree, the pictures on the left look decently exposed, the effect makes them appear a bit darker but check the whites, they're still exposed ideally.

SlamDesi wrote:

I'm will Peter on this one. I used to slap a polarizer on quite a bit but, I find 'em to make the sky unnaturally dark. With software, one can tweak that in a bit if necessary anyway. I find them more useful in adjusting the reflections on water. I have a couple of different CPLs and they're a lot different in the variance of effect and how subtly you can apply it. Thanks for posting it, Manual.

Like you, I have found a lot of differences in degree of effect from different polarize filter manufacturers. It's one of the reasons I like the current CPLs I use. It has a strong and very rapid response to reflected light. It's easy to find maximum polarization effect. Although I must say, I see the potential benefit of finding some balance between full and non.

The big issue with CPLs is how they darken the sky. You can get it to go black under the right conditions. If you are looking for "naturalness", this is a problem.

Outside of the sky, to my eye, it is the increased contrast and clarity that is most intriguing. The elimination of all that reflected light makes increases contrast, sharpens the edges, colors a bit deeper, leaves more pronounced, etc. Can you dial down the blue sky effect and still get the pop for the polarization effect? I'm willing to find out.

Personally, I don't mind the dark sky. In this context I'm trying to show the power of the steeple in getting people to see the church. A dark featureless sky makes the steeple front and center.

MightyMike wrote:

manual_focus wrote:

PeterPentax wrote:

manual_focus wrote:

One additional note is that while the camera settings were the same, the shutter speed was two full stops difference (1/1600 sec vs 1/400 sec) without and with the filter. The CPL is removing a lot of polarized light which accounts for the differences

CPL's darken the light from an image. Due to their nature, they darken polarised light more than non-polarised light.

You need to take this into account when you use CPL filters. Your shots with the filter look under-exposed to me.

Yes, the CPL reduces the amount of light getting to the sensor because it is not clear glass and because it blocks light of a particular polarization. With my CPL I needed to increase the amount of light to the sensor by four fold (2 stops). Your description of a CPL may need some more thought. See: https://en.wikipedia.org/wiki/Polarizer#Circular_polarizers

Interesting as to your comment that the filtered images (on the left) look under-exposed.

I disagree, the pictures on the left look decently exposed, the effect makes them appear a bit darker but check the whites, they're still exposed ideally.

Who am I to argue? I can say this. The highlights would blow out with a longer exposure. Take a look, I used multi-pattern metering and still had to dial it down -1.0 to -1.3 eV. so as to not blow the highlights (white columns) out. The RGB luminous values for the columns are around 240s. It is not under-exposed.

DougOB wrote:

kypfer wrote:

Just remember you don't need to use the polariser at "full" setting, often a "half-way there" can give a pleasing contrast without "over-cooking" it … well worth taking two or three shots at slightly differing degrees of filtration then assessing the results when you get home. Just make a few notes as you go, the filter settings aren't recorded in EXIF

This is one of those basic pieces of advice that, duh, I never thought of. Now is my memory good enough to put it into practice...

Thanks,

Doug

Exactly.

Thanks for all the comments. Good discussion.

As an adjunct to my original post. Here is a full size image showing what the DA*50-135mm with the K3-2 can do. Based on my experience you could get a bit more detail if I had set it up on a tripod and used Pixel Shift. Another day.

Enjoy!

Impressive.

manual_focus wrote:

To see what the differences were I shot two scenes with and without a CPL.

There seems to be a difference between CPLs:

https://www.lenstip.com/139.25-article-Polarizing_filters_test_2015_Results_and_summary.html

Many years ago I bought a B&W CPL, which I hardly used. Oiche mentioned the Hoya Fusion Antistatic CIR-PL, which I bought this year. I am quite happy using it.

tex wrote:

In 2005 after a trip to Turkey, where i used a polarizer quite a bit, I saw the results and decided that with digital my needs had changed.

I only use them now to control reflections, mostly in my work shooting museum collections and exhibitions---still need them for that. For skies? Not at all.

This is exactly my finding. While I used it on my film cameras almost permanently, the digital files can be so flexibly post-processed, that I don't find any reason for the polarizer. Except to control reflections.