Circular polarizer on a UWA lens

[squarebox]

I've been seeing conflicting opinions on whether or not to use a polarizer on a wide angle lens.  I've seen alot of reviews where people mention that because of the wide DOF, you'll uneven light levels across the scene when using a circular polarizer.  But then on the other hand I see other blogs where people say the complete opposite, that for taking photos of landscapes it is a must.

Can anyone shed some light on what the issues are and when it's ok to use a polarizer on a UWA lens.  Specifically thinking about the 16-35L

[thebowtie]

I've been seeing conflicting opinions on whether or not to use a polarizer on a wide angle lens.  I've seen alot of reviews where people mention that because of the wide DOF, you'll uneven light levels across the scene when using a circular polarizer.  But then on the other hand I see other blogs where people say the complete opposite, that for taking photos of landscapes it is a must.

Can anyone shed some light on what the issues are and when it's ok to use a polarizer on a UWA lens.  Specifically thinking about the 16-35L

I like to use a Circular polarizer for landscapes too - it certainly helps with sky and clouds, as well as situations where reflections on water or windows is to be minimized.
I have found that using a UWA lens (mine is a 16-35 2.8L II) on a crop body (50D) I get uneven color toning at wide angles due to the geometry of the lens and the way light passes through it.
I've also heard that on a FF body the effect is more noticeable because you get the entire image from the lens, not just the cropped portion in the center.

So - should you go for a CP on an UWA lens for landscapes?
Depends on

• Crop factor (FF vs APS-x)
• Lens quality & Focal-length(vignetting)
• Filter quality (thin filters better than thick)
• What you are trying to achieve, generally.

You might be able to achieve more dramatic effects, with a better result by managing exposure and using post-processing instead.

Your mileage will vary.

[neuroanatomist]

Uneven polarization occurs at angles of view wider than ~24-28mm (on FF).  Whether or not the effect is visible in your image depends on the lighting and the scene.

If a blue sky extends across the image, you'll likely see the unevenness (assuming the sun is at an angle allowing polarization).  Even then, it doesn't always detract from the image.  But...a CPL can, for example, increase saturation of fall foliage shots where uneven polarization isn't evident, and it really adds pop to the image.  Also great for waterfalls (reduces reflections).

I have an 82mm B+W Käsemann CPL that I use with my 16-35 f/2.8L II.  It helps that I also have TS-E 24mm f/3.5L II that also takes 82mm filters, as does the 24-70 II that I'll likely be getting.

[dr croubie]

Damn, I was hoping to find an example photo of mine that shows off the effect perfectly, but that'll have to wait until i get home. When you use a CPL, there's an area of sky that gets 'bluer' or 'darker' or whatever you want to call it. That area is a fixed size (ok, depending on a few factors, but near enough to the same size) with soft-ish edges. The wider your lens, the more likely you are to see both edges in the frame at once.

I've got a 7D and EFs 15-85, at the wide end that's 24mm FF-equivalent. Using a Polariser with a lens this wide, the effect is certainly noticeable.
Whether or not it's a bad thing, though, is up to personal taste.
At 15mm/24mmFF, I don't mind it so much, possibly because the vignetting of the 15-85 kind of counteracts it. Any wider and it'll be more and more noticeable, hopefully someone else can post examples...

[revup67]

To the best of my recollection this shot was taken with a Marumi Cr. Polarizer on a 16-35mm USM 2.8 II  on a 5D MK3.  No noticeable vignetting in this shot in any of the corners though I have to agree with Neuro on the the scene as the vignetting depends on the factors he mentioned.  My image is to show it is possible to not have this effect.  I may have also used the DLO in DPP when I orignally processed this RAW which may have helped as well.

This one taken at 16mm, ISO 50, F11, 1/80, -1/3 EV

[dr croubie]

Mmm, I forgot to add in my example I was talking about.
Anyway, this is 7D, EF-s 15-85 @ 15mm, f/14, iso400, 1/60s (ok, maybe too high f and iso, but it's one of the first shots I took with my camera when I got it, specifically to try out the CPL), and a Fujiyama 72mm CPL.

No marks for composition on this probably, it was only a test shot.
You can clearly see the blue banding directly in the centre of frame, but it's not "bad" by some definitions, at least it's not distracting or annoying.
No idea where the sun was, but it was taken at 10am in Europe Summer Time (presuming i'd set the clock correctly), I've checked a map and I was facing roughly NNW, so sun is just behind my left shoulder if not directly behind me.

So given how noticeable it is here (24mm FF), it's only going to be noticeable even wider, in fact I just bought the Sigma 8-16mm because I didn't care about not being able to put CPLs on that huge bulb of a front element.
Facing perpendicular to the sun gives you a better CPL effect, so maybe it wouldn't be more noticeable wider then, I'm not sure...

[revup67]

I think someone else pointed out not all filters are the same of course.  I've had excellent success with the Marumi specifically the Super DHG model which received one of the highest ratings.  Go to this link and scroll down to vignetting then note they took first place just below that section

http://www.lenstip.com/115.24-article-Polarizing_filters_test_Marumi_DHG_Super_Circular_P.L.D_72_mm.html

[neuroanatomist]

I think someone else pointed out not all filters are the same of course.  I've had excellent success with the Marumi specifically the Super DHG model which received one of the highest ratings.  Go to this link and scroll down to vignetting then note they took first place just below that section

http://www.lenstip.com/115.24-article-Polarizing_filters_test_Marumi_DHG_Super_Circular_P.L.D_72_mm.html

But do note that even the absolute best quality CPL will still show uneven polarization with UWA lenses, unless Marumi has developed a filter that changes the basic laws of optical physics...