K5 and circular polarizers

[mggm59]

<p>After noticing the issue in pictures taken in many different conditions, I have reached the conclusion that the angle at which the polarizer is set can change drastically the color temperature of the pictures. In some positions the global tone is much colder than in other. For what I know of polarizers, they should change the density of certain colors (like blue sky) but not the color of, say, rocks, while it is evident that often the whole picture is affected.<br>

Anyone noticed the same issue? Any explanation?</p>

<p> </p>

[snik75]

<p>I have had that experience with cheap polarizers, and was under the impression it stemmed from the low quality of the filter. I have never sprung for a good quality one to test, though.</p>

[stemked]

<p>As Nick noted I have seen same. Once upon a time a friend of mine using Quartinary Filters came back with purple sky photos. Great if it was Alpha Centory, not great from the Grand Canyon.</p>

[keith reeder]

<p>"Quantaray", Doug?</p>

[mggm59]

<p>Dunno, one is a Kenko, the other is a Vivitar, are these such low quality? I'll try with the B+W I have for smaller diameter lenses and see if in the same conditions it has the same effect. Only, I'll have to wait some time, 'cos in Belgium it's not exactly blue skies nowadays...<br>

However, can't understand the reason, the filter grey seems neutral and polarization should not influence non reflecting objects like rocks (see example, same lens, same time, same rocks)</p><div></div>

[mggm59]

<p>and this is colder</p><div></div>

[michael_elenko]

<p>When using circular Polarizing filters with very wide angle lenses you will get density variations across the plane which may affect color perception. Your first shot displays this.<br>

<br />Spend the money on the best you can afford.</p>

<p>ME</p>

[mggm59]

<p>For a 77mm like the 12-24 that's quite hard… maybe next time I go to the US with a low dollar ;-) However, density is indeed an issue, but the same rocks and sand look cold pink in one and yellowish in the other on the whole width of the picture</p>

[pj_vesterback]

<p>What is your white balance in each photo?</p>

[mggm59]

<p>AWB in both cases, good idea, it might really be that it "feels" the polarizer as a different color temperature. The sky is bluer in the cooler picture, but not so much than on the right side of the first one, however. When I do tests I'll try with a daylight white balance and see if the difference goes away. </p>

[trw]

<p>This is almost certainly an AWB issue. Polarizers increase saturation but rarely change colour. If it was changing colour you'd see it in the viewfinder. AWB depends on the camera being able to guess what the colour should be - usually based on assuming the colours balance out to grey over the whole field (this is almost always incorrect but sometimes close enough). When you have large expanses of saturated colours it will get thrown for a loop on any camera.</p>

<p> </p>

[andrewg_ny]

<p>Maurizio, you may also have noticed that filters can easily cause vignetting on the 12-24 (check the corners on the images you posted!). When you do buy, you might want to get one of the 'slim' filters to minimize this.</p>

[mggm59]

<p>Thanks, I actually bought the Vivitar, which is thin, afterwards during a layover in Miami. Now I use the Kenko on the 28-70/17-70 via an adapter or on the 70-200 directly, where vignetting it is not an issue although with the 28-70 lens shade TURNING the damn thing IS a problem.<br>

About AWB, it's understandable, yet it should give the same problems then when taking pictures of, say, a blue sea, but I don't remember a case where I was aware of such an effect.</p>

[andcompany]

<p>Defenitely an AWB issue. But not really an 'issue' since raw images are going to be modified anyways to get it perfect. Clear skies + superwides + polarizers(especially when shot at 90° to the sun) can have negative effects. The polarized area does not cover the superwide's fov.</p>

[andcompany]

<p>I use Kenko Zeta (Hoya HD) because it's a compromise between price and quality. It's coated glass and a 77mm is around 150.</p>