Circular polarizer slight blue cast

This may be completely normal, but when I use my B+W MRC Circular Polarizing filter and take pictures of people, the resulting skin tone has a very slight blue cast.

Do I have the wrong circular polarizing filter for this application (i.e., should I be using a "warm" CP)? Also, if anyone has some basic steps for removing this blue cast in PS I'd appreciate the advice. I'd post some images, but my wife is opposed to displaying images of the kids on the internet ... and it's only noticeable with skin tones.

You can blur-out the kids' faces or crop them out .

I know, but it's the faces that have the blue cast

I was able to improve the color by adjusting the white balance for converting from Raw to jpeg. The shots were all taken on a bright sunny day where the AWB looks to be 5200K. Increasing to 6000K (cloudy setting) warms the images up so that they look natural.

is this typical?

When I shoot raw, I always find that my pictures look cool (from a colour sense!).

I can choose daylight colour temperature in my raw conversion software, but that seems too much the other way. With a portrait shot, it is not colour critical and you can select whichever appeals most to you. The point is that it can be done after the shot has been taken.

If colour is more critical, the inclusion of a grey card in one of the shots will allow you to balance the colour to be neutral.

I would say the cool colour is normal, but have only my camera to compare against. That is true with all my lenses.

Graham
nb take a self portrait with the timer – or picture of your arm or something.

Thanks Graham,

Without the polarizer my outdoor shots of people look spot on, but of course the sky doesn't look nearly as nice as when the polarizer is used, and vegetation etc. has great colour/saturation. I just read an article stating that some cheap CP's give a color cast, so buy a good multicoated one which won't. I thought I did with the B+W ... but maybe not ... or maybe they all give a very slight color cast and my experience is normal.

At least I can see that it is easy corrected by an +800K adjustment to the white balance, which is probably easier to swallow than buying a warm polarizer (with 81A).

Other than this small issue I've been really happy with the B+W CP.

EDIT: I just opened my pics in Raw Shooter Essentials and it reports the white balance to be 4550K (images taken in bright sunlight, no clouds). When I change it to 5200K (typical daylight), the white balance is spot on (a delta of 650K).

Sorry Bob, I saw cool and completely forgot you mentioned the cp. I am getting the same one as well, so good choice

I think that is about as good as cp's go, so I don't think it will be a 'quality' issue. If it can be fixed so easily, that's good to know. Whilst you can do with it what you choose, a cp loses a stop or two and typically is better suited to landscapes, rather than portraits.

One always has to remember that the monitor may not be 'accurate', although that is only relevant when you output to print. In other words, if what you see on screen more or less matches your output device or photo processing lab. It could be that you are going too far in the warm direction when printed if it is not accurate.

Graham

Thanks again Graham,

I printed a few for comparison and +600 to maybe +800 works pretty well (hard to tell the difference on a small print). The prints without correcting white balance are just off by a very small amount for sking tones ... although for scenery things look fantastic.

I appreciate your comment that this is as good as it gets. The correction is simple, so I don't mind doing it. Just wondering if a "warm" CP with an 81A filter built in has about the same degree of correction?

I have a CR1.5 filter on one of my lenses (as they all shot cold, I figured it wouldn't hurt and it was second hand and cheap). I think the difference is very subtle.

If I get chance I will do a shot with and without the filter and see if there is a difference and post it. I guess it depends on how warm it is to start with. A much warmer shot would probably not be noticeable, whereas a cool shot may be quite different. We shall have to see!

Graham

Without and with the CR1.5

According to photoshop without 4850 and with 4550 (or the other way round – I'm juggling work at the moment).

Hope that helps.

Graham

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Thanks very much Graham ... this really helped. I'm now convinced that my result is totally normal, so if I continue to use a CP when taking photos of people the options are:

1. Buy a separate 81A filter to stack with the CP (adds 800K to 1000K) - $77
2. Buy a "warm" CP (81A built in) - $205
3. Keep using just what I have and bump the white balance a bit for the Raw conversion - Free

I am inclined to think one should shoot as neutrally as possible and only adjust on a case by case basis for the very best quality. It is easy enough to batch convert with your favourite setting if required.

My filter gives more warm colours that might be difficult to tone-down. If you like the effect, then that's fine. If it's not appropriate, it can be a bit difficult. If you do your portraits early in the morning or evening, it may be too much, but at mid-day it may really help.

I guess with the filter, you always have the option to remove it.

My take on your original question – sort it in post production.

Graham