Exercise 10: COLOUR CAST AND WHITE BALANCE

It is a fact that no camera can adjust automatically to the scene, the way human eye does. Once the camera captures the image it obviously gets transferred and then subsequently is viewed on different display, all these factors affect the colour balance of the image. Hence it is very important that before the capture, we adjust the white balance in the camera. Other option is to make an adjustment at the post processing level. This exercise is focused on explaining the white balance options of the camera.

So, in short white balance is the option/method of ensuring, that the objects are rendered with closest colour perfection in our photos. In my camera (and in most of the DSLRs) there are 3 ways of making these adjustments.

  1. I let the camera do the adjustments – Auto mode
  2. I use predetermined options for the white balance
  3. I use the pre-set option. For this, I need to use a white patch for the camera’s readings and then save the readings as the pre-set. I can save up to 5 pre-sets.

In my DSLR, I have several options to set the white balance:

  • Auto: 3,500 – 8000k

This is a safe option. I just need to trust the camera to do the adjustment, however the results are not constant and they change shot to     shot. If built-in or optional flash fires, results are adjusted for the flash.

  • Incandescent: 3000k
  • Fluorescent: 2,700 – 7,200k
  • Direct sunlight: 5,200k
  • Flash: 5,400k
  • Cloudy: 6000k
  • Shade: 8000k
  • Choose colour temp: 2,500 – 10,000k
  • PRE preset manual: option to set it myself

There are two very good articles available on the web to understand this in-depth.

Author: Sean McHugh, read it on 12/12/11

http://www.cambridgeincolour.com/tutorials/white-balance.htm

Wikipedia: read it on 13/12/11

http://en.wikipedia.org/wiki/White_balance

As per the exercise requirement, I have chosen 4 different light conditions.  For each of them, I have used four different colour temperatures. The results are as below:

Sunlight:

WB Auto: 4550k WB Sunlight: 5000k
Sunny Day-1 Sunny Day-2
WB Cloudy: 5650k WB Shade: 7200k
Sunny Day-3 Sunny Day-4

For this light condition my personal favorite is sunlight. With WB set to sunlight the details in the shadow are more clearly visible.

Cloudy

Now when I am waiting for a cloudy day, it refuses to get cloudy. Hence, I have decided to select a photo, that I had clicked some time back on a cloudy day. I have changed the temperature levels in Lightroom 3.

WB Auto: 4200k WB Sunlight: 5200k
Cloudy-Auto Cloudy-sunlight
WB Cloudy: 6000k WB Shade: 8000k
Cloudy-cloudy Cloudy-shade

I remember the scene vividly. In spite of being cloudy the sunlight was quite prominent due to the sun being positioned quite close to the horizon (and that side it was not cloudy). We get to see such cloudy days, followed by heavy rains and powerful thunder and lightening quite often.

Coming back to the exercise. I don’t like the way “Auto” WB has cooled down the temperatures. It is also giving a blue tint, which is not the correct representation of the scene.  “Sunlight” WB is giving an ok results. The most realistic results are with the “Cloudy” WB. I do not like the option “Shade” WB here as it has produced yellow colour cast.

Open shade on a sunny day:

For this, I placed my model near the sliding door and opened the door fully. It was a perfect sunny day. However, there was no direct sunlight hitting the model or surrounding areas.

WB Auto: 4850k WB Sunlight: 5000k
Open shade on a sunny day-1 Open shade on a sunny day-2
WB Cloudy: 5650k WB Shade: 7200k
Open shade on a sunny day-3 Open shade on a sunny day-4

Though these images were shot in the shade, the option “shade” is not offering a natural colour tone. The tint of yellow is bit strong. I am undecided between the option “sunlight” and “cloudy”. I would select option “sunlight” and fine-tune the values with multi selector.

Mixed Lighting

WB Sunlight: 5000k WB Incandescent: 2950k WB Auto: 3400k
ML-Sunlight-3 ML-Incad-2 ML-Auto-1

In this light condition, I feel the Incandescent WB has given ok results. It has brought down the yellow colour-cast significantly and has neutralized the tones reasonably. Notice the color of the sky. However, I would like to fine-tune the values of “incandescent” and reduced the yellow colour-cast further.

Conclusion:

The AWB has a limited range; it doesn’t handle flash well and has limited accuracy.  Prior to this exercise, I have always adjusted the WB according to the scene requirement. I feel comfortable, if I fine-tune the adjustment in the camera, so there is very little left to do in Lightroom.

While shooting objects or materials containing white color, it is important to get the correct white balance. To active this, it makes sense to have the pre-set values saved. As a result, on site WB selection becomes comparatively easy.

I have not checked the results with flash. It will be interesting to know how WB works with it.

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