Getting Control Over Colour Cast

You already know that your shots of night-life downtown will not be exactly right unless you set the White Balance of your camera to tungsten.  And if you didn't...  give it a try.  Set up to shoot any scene that is artificially lit, but make sure that your camera's White Balance is set to daylight.  Do the shot, and then repeat it, with the camera's White Balance set to tungsten.

The second shot will be much cooler, with fewer warm tones, and will be more...well...night-like. 

Click here for full-sized image

ND2_27780

Look at this!  This leafy, shaded area in the park has created a green light which is far too obvious and unacceptable!

The human brain adapts to colour casts, and makes adjustments.  The camera is more literal, and does not.

This leads to situations like the photoshoot we did with Jennifer in a leafy section of the park.  Anybody looking at the image knows instantly that the green colour cast is a problem.  It needs fixing!

One way to side-step that particular technical problem is set the camera to Auto White Balance.  Weird situations are then dealt with by the camerra.

But it can lead to disappointing results. 

In rock concerts, the amount and colour of the light changes rapidly and wildly.  Using Auto White Balance in this situation can be very disappointing.  The results will be inconsistent, often too warm and often lacking the colour that you want the image to have.

Click here for full-sized image

DSC_7569 - Eppiphane - The Big Money Concert

Notice the deep blues.  The only truly warm light is where the light is white and warm.  The other lights have rich colours.

Over time, I have decided that Auto White Balance leaves me with a group of images that don't seem to have a colour unity, and which are had to deal with in post-processing.  I find that I am much happier if I set the camera's White Balance to "tungsten." Sure, the colour can vary wildly from shot-to-shot, but somehow there is a better sense of the mood and light of the concert.

Gymnasiums are another area that can be tough.  The lights of gymnasiums emit a weird and incomplete spectrum of colour, and sessions shot under this kind of light were very hard to correct in post-processing.

These two categories of experience have caused me to pretty much abandon Auto White Balance.  These days, I use one of the presets (Daylight, Tungsten, Flash, Fluorescent) which means that shots have some kind of colour unity, and then I correct in post-processing.

And I often use a Custom White Balance. 

Click here for full-sized image

ND2_26500

That card that Caitlin is holding, is a "Digital Image Card," or "Studio White Balance Card." By pressing the right combination of buttons on my Nikon, I can cause the camera to evaluate the light reflected from the card, with a resulting "Custom White Balance."

The card is different from the Kodak 18% Gray Card that we use to measure exposure.  Apparently the 18% card does not reliably reflect the light colour and therefore this specialized card is needed.

There is no picture saved when you click the shutter to produce the custom white balance.  You get some feedback telling you whether the processed worked, or not.  That is all. 

So I normally also take a picture that contains the card.  In this case, the picture with Jennifer.  This is worthwhile.  Later, in post-processing, I can check the image with Photoshop or Nikon Capture, and assure myself that the colours are indeed right.

I have found that, for whatever reason, I prefer the results from Custom White Balance over Auto White Balance.  In gymnasium settings, Custom White Balance works.

Click here for full-sized image

ND2_27783

Open the "Before" and "After" pictures and compare.  Not that you really need to.  It really becomes apparent in the white of the dress.

Yes, there are problems with the resulting colour in images of Jennifer, but they are much reduced and the resulting images are readily appealing.

For me, it has been really helpful to put a gray card in the picture at the beginning of the shoot.  I often need the reassurance that the colour in the photograph is right, or the reminder that I should perhaps leave the colour alone!

In the barn shoot, seen above, I lit the seen with light reflected from a gold and silver reflector.  This is probably something I shouldn't have done.  It was interesting, but it was confusing.  By referring to the gray card in the shot, I was able to reassure myself about the colours.

The digital gray card can be obtain from Henry's.  The product listing is "Digital Gray Card 4"X6" DGC-100." B&H sells it as "Digital Grey Kard - Studio White Balance Card;" it's the same manufacturer, but a different size.  Vistek sells it as "Porta-Brace WBC White Balance Card." It's much cheaper, and proibably noit the same manufacturer.

There are other ways to generate a Custom White Balance.  One of the best known is by using an Expodisc White Balance Filter.  This fits over the lens, like a filter.  But it costs five times as much, looks like it could be damaged easily, and cannot be incorporated into a test photograph.

Posted July 20, 2012 at 10:09 pm.