Polarizer problem.

[David Anderson]

Hi all,

I don't use polarizers much so please forgive me if this is a stupid question -  

I did this shot on a 1DsII with a 16-35 II (16mm) and a new 82mm Sigma EX circ. Polarizer - as you can see the sky is darker in the middle.
It never happened on my Mk I 16-35 with a Hoya filter..
Looks like the filter can't cover the wide angle  ?

The shot is lit from the side and scrimed from above.
(assistant has long arms   )

Is it me or the filter or maybe an act of god ?

[Nick Rains]

Is it me or the filter or maybe an act of god ?


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Hi Dave

Not you, not an act of God, just the way polarisers work. It is a very typical issue using Pols with superwide lenses.

If it was the coverage of the filter size you would see edge clipping and edge darkness, the centre darkness is simply the polariser darkening the sky most at 90 degrees to the sun. Such a wide lens tends to include other parts of the sky that are darkened less - thus the graduated effect. I suspect that the shot was taken with the sun fairly low?

Two ways around it -

1. Polarise 'less'. ie twiddle the filter away from its maximum effect.
2. Use RAW processing settings to get the same dark blue effect ie don't use the polariser. Lightroom/ACR4.2 has excellent tools for this.

HTH

[David Anderson]

Bugger - my fault huh ?  

Thanks Nick, I normally wouldn't use one for this sort of shot I was just trying to take the edge off the hard flare on the Hay..

I'll have a look at lightroom.

[Monito]

Use tripod, take two shots, one that minimizes hay bale reflections, and second that optimizes the combination of the sky and the man.  Mask in the hay bales into the second shot during post processing.

Polarization is selective depending on the angle with the sun.  An ultrawide angle is going to encompass a wide rangle of angles to sun.

Another approach is to use less wide of an angle.