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Archive 2012 · Using polarizer below 35mm FF
  
 
ben egbert
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p.1 #1 · p.1 #1 · Using polarizer below 35mm FF


There seems to be two schools here, one says don't use polarizer below 35mm (choose your own cut off). The other uses them all the way down to 17 or so, assuming with some adjustment for uneven sky.

I have tried both and always end up with bad skys below 35mm. If you adjust for an intermediate polarization, you often get a dark band in the center.

So the question is really about technique. How do you eliminate uneven skys with a polarizer on WA shots.

By the way, Ziess has a new CPL available to fit the announced 15 f2.8.




Jul 21, 2012 at 06:19 PM
ben egbert
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p.1 #2 · p.1 #2 · Using polarizer below 35mm FF


C'mon guys, this is a really good question. Certainly some of you have opinions or technique. How about posting some UWA polarizer shots that include blue sky.


Jul 22, 2012 at 02:07 PM
jamesf99
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p.1 #3 · p.1 #3 · Using polarizer below 35mm FF


ben egbert wrote:
There seems to be two schools here, one says don't use polarizer below 35mm (choose your own cut off). The other uses them all the way down to 17 or so, assuming with some adjustment for uneven sky.

I have tried both and always end up with bad skys below 35mm. If you adjust for an intermediate polarization, you often get a dark band in the center.

So the question is really about technique. How do you eliminate uneven skys with a polarizer on WA shots.

By the way, Ziess has a new CPL available to fit the announced 15 f2.8.


You're right, it's a problem, but what'cha gonna do? I haven't solved it, I just live with it.

The angle of view is simply too great to maintain the CP's most effective angle of 90 degrees. The only real solution if you don't want to polarize is to either use ND grads, take multiple shots and stack, use HDR, or dual/triple process your single images.

Actually the best place to ask this question is the landscape forum.



Jul 22, 2012 at 02:38 PM
ben egbert
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p.1 #4 · p.1 #4 · Using polarizer below 35mm FF


jamesf99 wrote:
You're right, it's a problem, but what'cha gonna do? I haven't solved it, I just live with it.

The angle of view is simply too great to maintain the CP's most effective angle of 90 degrees. The only real solution if you don't want to polarize is to either use ND grads, take multiple shots and stack, use HDR, or dual/triple process your single images.

Actually the best place to ask this question is the landscape forum.



Thanks for the reply, and your answer is like mine. I did not post this at landscape because I am pretty sure it would get moved for being off topic.




Jul 22, 2012 at 02:50 PM
Roland W
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p.1 #5 · p.1 #5 · Using polarizer below 35mm FF


If you are only worried about variations in the blue improvement of the sky, then your question is indeed about processing. I do tend to avoid a polarizer on a wide lens if I have a lot of clear blue sky in the shot, but use a polarizer down through 16mm fairly often for other reasons. I wanted to mention some of those things just so everyone will not totally discount a polarizer for wides.

The reduction of water reflection is an important use, and being able to adjust to taste what your result will be is valuable. I often even shoot with several different polarizer settings. And many water reflection compositons do not include any sky at all, or the light is more diffuse so sky variation is not an issue.

The increase in color saturation for some types of rocks, and also for green foilage, are probably my main use, and the improvement can be dramatic. The red rocks of the American Southwest are an example where the improvement is very nice. Nothing says that your composition needs to include blue sky.

And haze reduction for distant scenes can still be useful if the sky is not blue at the horizon. The right mix of clouds in the distance can mean that there is little if any blue sky to cause variation. A telephoto shot is one that more often needs haze reduction, but some wide shots do too.



Jul 22, 2012 at 04:13 PM
ben egbert
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p.1 #6 · p.1 #6 · Using polarizer below 35mm FF


Good reply, essentially choosing the right subject matter.

I never considered the processing forum but thought this a gear question, but you are correct. it is mostly about getting the image, a technique question.

I don't see too many forums dedicated to technique. it seems that landscape forums are more about presentation and processing is of course after the image capture.




Jul 22, 2012 at 04:19 PM
Ruahrc
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p.1 #7 · p.1 #7 · Using polarizer below 35mm FF


A related question, I know that for darkening skies, there is a limited angle over which the CP is effective, and this angle also relates to the position of the sun.

However, for the other uses (reducing glare off foliage/rocks/water/etc) does the same limitation apply? Or can you get enhancing effects even when you are pointed right at the sun or right away from the sun?

I'm pretty sure, given my understanding of the physics, that the position of the sun does not matter in the second case, but I am curious if anyone is sure.

To answer your question Ben, I use my CP on ultrawide lenses. Again it does come down to the composition and the subject. If there is a big swath of clear sky then I may not use the CP, but I find often times that either due to the environmental conditions (such as cloud cover) or compositional considerations (presence of mountains, etc) much of the sky is blocked out and using the CP is fine. Also, personally I am usually not that bothered by an uneven sky in a photo- after all the brightness of the sky may still not be uniform with a wide FOV even if you took the CP off, since the closer towards the sun you point, the brighter the sky gets.

Norman



Jul 23, 2012 at 08:44 PM
ben egbert
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p.1 #8 · p.1 #8 · Using polarizer below 35mm FF


Don't know the answer to your question.

On sky variance, the problem I have is not being able to see it on the viewfinder or LCD and only seeing it at home where it is too late to fix. Of course I can see gross variations, but not the sort that I see at home. The dark upper corners are easy to see and what you get with full effect, but if you turn it for less effect, you often get a dark center which never looks right.

I guess I am not able to see when I have an even sky when in the field. The real solution is to be sure and get some good exposures without the polorizer.



Jul 23, 2012 at 09:01 PM
 

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matthewbmedia
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p.1 #9 · p.1 #9 · Using polarizer below 35mm FF


I use a CPL on my canon 16-35 all the time - Below about 20mm you have to be careful obviously and I tend to get the best /most even sky results shooting about 45 degrees away from the sun.

BUT! I usually don't use a CPL just to darken the sky - my usages are more for reducing glare/reflections on skin, windows, buildings, grass, water, etc.



Jul 24, 2012 at 07:36 PM
matthewbmedia
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p.1 #10 · p.1 #10 · Using polarizer below 35mm FF


Here's a straight out of camera, unprocessed shot from a 5dii at 16 with a CPL - (the bottom has been cropped a little) - note this is just for an example and is obviously not meant for artistic production. The sun is about 25-40 degrees off my right shoulder - so total angle from lens vector to sun is 40-60 degrees maybe. (not a full 90)




Jul 24, 2012 at 07:45 PM
ben egbert
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p.1 #11 · p.1 #11 · Using polarizer below 35mm FF


Ok, the vignetting here could be corrected in ACR. Not so easy with a dark center band. The clouds help a bit here as well.


Jul 24, 2012 at 08:45 PM
matthewbmedia
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p.1 #12 · p.1 #12 · Using polarizer below 35mm FF


Yep - if i was a full 90 from the sun - the dark left corner would be in the center -

At that point I'd brush in a curves adjustment in aperture or an exposure layer in PS - in PS most likely I would just use an adjustment layer with a center drawn gradient - and brush out the bottom half.



Jul 24, 2012 at 10:15 PM
Pixel Perfect
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p.1 #13 · p.1 #13 · Using polarizer below 35mm FF


ben egbert wrote:
There seems to be two schools here, one says don't use polarizer below 35mm (choose your own cut off). The other uses them all the way down to 17 or so, assuming with some adjustment for uneven sky.

I have tried both and always end up with bad skys below 35mm. If you adjust for an intermediate polarization, you often get a dark band in the center.

So the question is really about technique. How do you eliminate uneven skys with a polarizer on WA shots.

By the way, Ziess has a new CPL available to fit the announced 15 f2.8.



I happy down to 24mm for pure blue skies. If there's scattered cloud I'll use 17mm as you don't notice the variation nearly as much and a bit of PP can quickly even out major differences. If it's a pure blue sky anyway you can PP the sky sans polarizer to get richer blues. If you have water or shiny foliage in the scene, you can take two shots; one with the polarizer adjusted to remove glare, one without for the sky and blend them.



Jul 26, 2012 at 02:07 AM
ben egbert
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p.1 #14 · p.1 #14 · Using polarizer below 35mm FF


My Lee 4x4 polarizer arrives soon so I will give it a try on my 17TSE. The first one arrived broken and had to be returned.

I have a 105 B&W screw in that fits my Lee hood system but it vignettes on the 17.



Jul 26, 2012 at 02:21 AM
dsjtecserv
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p.1 #15 · p.1 #15 · Using polarizer below 35mm FF


Ruahrc, I'll take a shot at your question:

for subjects of the than the sky, the angle you are pointing the camera relative to the sun (or other light source) doesn't matter. The sky effect is because the proportion of polarized light is greatest at an angle 90 degrees from the sun, relative to the observer, and is cause by the interaction of light with the atmosphere. The same thing doesn't happen with surfaces other than the sky.

However, angle still matters, but in a different way. The reflection from an object contains the greatest proportion of polarized light when it viewed at a specific angle, called the Brewsters angle, and thus the effect of a polarizer is greatest when the object plane is at this angle. The effect falls off gradually on either side of that angle, as the reflected light is less perfectly polarized. This is most readily observed by using a polarizer with a deep expanse of still water. As you rotate the polarizer the distance at which you see the greatest reduction in reflected glare with change from near to far. A polarizer is thus still effective when the angle is different from the Brewster's angle, but less so.

Not also that this doesn't have anything to do with the angle of the sun; it works the same on cloudy days or in the shade, or indoors. but it still a useful consideration when using a polarizer for objects other than the sky.

Dave



Jul 26, 2012 at 02:28 PM
ben egbert
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p.1 #16 · p.1 #16 · Using polarizer below 35mm FF


Dave, thanks for your explanation. The key is being able to see the effect on the LCD so that any sky banding can be reduced. I don't recall ever seeing any ill effect of a polarizer anywhere other than in sky's. Mechanical vignetting of course must be eliminated in any event but that is not my issue.


Jul 26, 2012 at 02:42 PM





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