Photography News 08

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Technique PHOTO SCHOOL

Camera class

1000K

Candlelight

2000K Sunrise/ sunset

Everyone has to start somewhere, even top pros, and in our regular Photo School feature we’re taking a close look at core techniques that every beginner needs to know. This month, in Camera class we look at the importance of controlling white-balance, while in Software Skills we see how to do this post-capture

3000K

Tungsten

4000K

Fluorescent

5000K

6000K Overcast daylight Noon sun Flash

lowest colour temperatures at around 1000-3000K, while the bluest light has the highest temperatures of up to about 10,000K. Neutral light, such as daylight, sits in the middle of the scale, at 5000-6000K (see the scale on the right). n What about other colours? Natural light varies along the blue-yellow colour temperature scale – consider how daylight varies through the day: blue at dawn, neutral at midday, and orange as the afternoon sun sinks. But artificial lights, particularly fluorescent ones, don’t mimic daylight accurately, and can introduce green or magenta casts – white-balance systems compensate for this too. n Howdoes this affect my pictures? The human brain is an amazing thing, and adapts in almost any lighting so that we see colours correctly. Even under street lights, for example, you can identify a white car, even though the light actually makes it look yellow. Cameras need help to adapt like this, and if the white-balance setting isn’t correct in this situation, the white car is recorded as yellow. You need to change the white-balance setting to put this right. n Howdo I usewhite-balance? With the latest cameras, using the auto white-balance system deals well with most lighting situations, but

this can trip up. The failsafe is to shoot Raw – this records unprocessed image data, so you can adjust white-balance after capture in software such as Adobe Lightroom – see how in Software Skills below. But getting it right in-camera means your preview is accurate, and saves time in post-processing. We’ll look at how you can do this in the next issue.

Words by Ian Fyfe

Amongst matters of exposure and composition, it’s easy to overlook colour accuracy. But ignore this, and your images suffer – off-colour images look wrong, can seem flat, and an unintentional colour cast can add an unwanted atmosphere. Getting this right means paying attention to white-balance – here, we look at what this is and how it affects your pictures. n What is white-balance? The white-balance setting compensates for colour casts created by different light sources. Setting it correctly ensures that neutral colours such as grey and white are reproduced as neutral, and all other colours appear accurate. It’s necessary because different light sources have different colour temperatures. n What is colour temperature? In its simplest terms, the colour temperature of a light source refers to how blue or yellow its light is. This is measured according to a standard scale with a scientific basis – skipping over the ins and outs, the only consequence of this you need to know in practice is that colour temperature is measured in kelvin (K), a scientific unit of temperature. Somewhat counter- intuitively, yellow or orange light sources have the Software skills Shoot Raw to adjust colour casts. Part 8: Fixingwhite-balance ADOBE LIGHTROOM Shoot Raw files and you have all the information you need to adjust the image’s white-balance (WB) all you like during processing. This is not possible with JPEGs. Enjoying this freedom in Adobe Lightroom is easy and it means if you prefer you can shoot with the camera in auto white-balance mode (or a preset) knowing you can fine-tune images later in software. Take this image shot under a bridge lit with tungsten lighting as an example. The tungsten lit areas have come out orange as you’d expect but this is readily resolved. Actually, because the image features a mix of tungsten lighting and daylight, correcting for the tungsten makes the areas lit by Words by Will Cheung

7000K

Shade

8000K

The influenceofwhite-balance

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10,000K Blue sky

NEXTMONTH: Take control of white-balance in- camera, and adjust

white-balance selectively in Lightroom

Colour temperatures too low (left) or high (right) give blue or yellow casts. The centre is neutral.

STEP 1 At the top of the Basic section in the Develop module click on As Shot and you have various preset options including Tungsten which is a quick fix for this image.

STEP 2 Or use the dropper tool. Click on the icon then move over to the preview image and click on the area you want to be neutral. The software does the rest. You might find your first attempt is not quite right, so try again.

BEFORE As shot, with no WB adjustment.

STEP 3Whichever you try, to fine- tune the result, move the Temp slider to adjust colour balance – indeed, you can go straight to this method. With this image, the slider to the right makes it more orange, to the left blue and more neutral. Adjust the slider while keeping an eye on the preview image and stop when it looks right.

AFTER WB adjusted for a more neutral image.

daylight blue, so it is a matter of getting a result you are happy with. Processing in Raw is non-destructive so if you’re not happy with your result use the History to go back to a previous state – or back to the original image.

Photography News | Issue 8

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