A Viewfinder Darkly

Photography tips and tutorials

Understanding White Balance

Light is not always white, even when it appears that way to the human eye. Our brains adjust automatically to slightly different coloured light and see the scene as if it is lit by white light.  Automatic White Balance (AWB) system in digital cameras or adjusting in Adobe Lightroom, makes it easy to get true colours under different lighting conditions.

Colour is not what it seems

Each light source is a slightly different colour. The measurement scale used to denote the colours is called the colour temperature, expressed in degrees Kelvin (K). This  temperature refers to the theoretical temperature of the light emitting source. Midday sun in a cloudless sky is considered to be white light with a colour temperature of 5600º K.  Artificial sources vary greatly in colour temperature with “warm white” incandescent lamps around 2500 K and “soft white” compact  fluorescent lights are around 3000º K. The emergence of compact fluorescent and LED lamps has complicated white balance as the new technologies have different colour temperatures.

afternoon scene

The late afternoon sun gives this scene a yellow look.

Even daylight is not the same colour. In the early morning and evening, the colour temperature lowers, giving a yellow colour to a scene, while grey clouds tend to produce a bluer or higher colour temperature. While it seems contradictory, the “warmer ” yellow colour temperatures are lower than the ‘colder’ blue colour temperatures and this is based our psychological reaction to the colours.

range of light

The colours temperatures of visible light

As well as the blue-yellow colour temperature regime, there is also a green-magenta tint component of White Balance in photography. The good news is that there are many aids for photographers in the camera and post processing to help get true colours in photographs.

AWB does this for cameras.

Digital cameras record the true colour of the light reflected from the scene. They have an adjusting mechanism called Automatic White Balance (AWB) that makes an adjustment to portray the colours as if the light is white.

This is a great advance over film cameras where you had to use a film formulated for the specific light conditions. The alternative is using filters mounted on the front of the lens to reduced the part of the colour range that would give a colour tint or cast in the photograph.

camera menu screen

Range of options for setting the white balance in the camera

The camera value of White Balance  is only a recommendation and is not applied until the image file is processed. Keeping the  raw image file for later processing gives total control over the White Balance.

Sometimes help is needed 

While cameras do an excellent job most of the time sometimes they get it wrong. And then there are scenes with mixed light sources. On these occasions, photographers need to help.

Many DSLR and advanced compact cameras have tools for setting the White Balance manually. When it is important to get the exact colour these tools are used to measure the White Balance. This is often the case in fashion or product photography where the colour is part of the story and near enough is not good enough.

To measure and set the camera’s White Balance involves taking a photograph of the scene with a large pure white object as the subject. This tells the camera that this is white and to use this as a reference for the White Balance.

For most photographers getting the exact colour right in the camera is not essential and is often easier to set in post processing using the raw image file. The White Balance is only applied when the raw file is processed. Processing in the camera and saving as a jpeg file reduces the options and control over the final White Balance of the photograph. The starting point for post processing colour temperature adjustment is the estimate by the camera when the photograph is taken, but this is more advisory than an essential part of the image.

White Balance adjustment

In raw file processing in Adobe Lightroom the White Balance can be adjusted to suit the photographer’s creative vision of the scene. There are a number of preset White Balance settings and a manual and automatic measuring tools for setting the White Balance. The danger here is that the colour displayed by the monitor may not be correct and so a colour cast is introduced when the photograph is printed or viewed on other devices. This highlights the need for a good correctly adjusted monitor for editing photographs.

If you are going to process the image in the camera to produce a jpeg then checking the White Balance is advisable because jpegs have less scope for adjusting white balance than unprocessed raw files.

lightroom menu

Lightroom preset white balance options. The options are far less for a jpeg shown on the left.

Lightroom Presets

Lightroom has a small pop-up  menu in the white balance adjusting area offering a choice of standard preset White Balance settings. There are more for raw files than processed jpeg or tiff files. Remember, Lightroom uses non-destructive editing so any changes to White Balance does not alter the original image file. This allows experimentation with the different settings with the effect shown in the preview window.

Measure the White Balance 

Lightroom has  an eyedropper tool for selecting a section of the image as the colour reference for the White Balance. Even though this is all about White Balance the eyedropper is used on a grey section of the image and not white.

The R G B numbers at the bottom of the eye dropper loupe are a guide.The value of the number is not critical,what is important is finding a spot in the photograph where they are equal, or close to it. This is the perfect neutral grey to use as the colour reference. The scale slider at the bottom of the preview window controls the size of the selection area. Normally I use a graphics tablet for Lightroom, but for this function I prefer to use the mouse as it easier to position it precisely on a patch of grey.

What if there is not any grey in the photograph? The precise colour is not important, what matters is matching the RGB numbers at the bottom of the loupe. Adding grey by taking a test shot of a standard 18% grey card is a common technique for providing a colour reference.

In Lightroom this White Balance measured from the grey card with the eye dropper tool can be used for other photographs taken under the same lighting conditions. There are two methods, copying or synchronising.

Lightroom window

Lightroom window with copy and sync buttons on the bottom of the two side panels

Syncing

This is selecting  photographs from  the grid view or the film strip and then clicking on one and then opening the Develop module. Make the White Balance adjustment and then click the sync button. When the Synchronise Settings popup appears check the White Balance box and uncheck all the others. This way only the White Balance adjustment is applied. Click on the synchronise button and the White Balance from the selected photograph that you adjusted is applied to all the highlighted photographs.

Copying

The Copy function is similar to Syncing except it is intended for one to one transfer of the White Balance setting between photographs.

Lightroom panel

The control panel for users to choose the adjustments to be copied or synchronised between photographs.

Manual Adjustment

When all else fails, or if one of the other methods is not close enough, there are adjustments for the basic colour temperature and the green/magenta tint. Drag the sliders or click on the number to the right of the slider and use the up and down arrow keys to for fine adjustment. Then adjust the image until the colour looks right on the monitor.

White balance choice

Colour conundrum. The table top is under a downlight giving a yellowish light, while the rest of the photograph is in daylight. Here are two white balance settings. So which one is right?

Lightroom Adjustments are Non-Destructive

The advantage of Lightroom and similar photo editing software applications is that the adjustment do not alter the original file. This means it is easy to experiment without losing any detail from the original. For White Balance, if you get lost and confused with different colour settings ii is easy to select the As Shot choice and start over.


Selective Adjustments in Lightroom

old mill building

Lightroom has an easy to use tool for selective exposure adjustments  of a photograph. This is because not all areas of a photograph need the same type or amount of adjustment.

The purpose of  selecting sections of a photograph for adjustment is to compensate for the inability of  cameras to capture the full range of light levels in a scene. When we look at a scene our eyes adjust as we look at different parts, but a camera has to make do with the one setting. Instead, the adjustments are made afterwards in software such as Adobe Lightroom.

This is not compensating for poor photographic technique, it is important to capture  as much detail as possible. Particularly not to overexpose the highlights because if they are lost then there is no way to recover them. Another important consideration is using the raw image file and not an already processed jpeg format image file. Raw files contain more information than jpegs about the scene, giving greater scope for adjustments in Lightroom. (more…)


Nikon 105mm Medium Telephoto Prime Lens

lens

Nikon celebrates the production of 100 Million Nikkor lenses by announcing a new premium medium telephoto lens.

“Surpassing the 100 million lenses produced milestone is a great honour and a testament to the photographers who both love and rely on NIKKOR glass to get the job done,” said Kosuke Kawaura, Director of Marketing and Planning, Nikon Inc.

The new Nikon lens is a 105mm prime lens with a wide f/1.4 maximum aperture suitable for  full-frame (FX-format) cameras.  The  NIKKOR f/1.4 lens is one of Nikon’s Gold Ring Series of lenses, which include only premium primes with Nano Crystal Coat and pro-grade build quality. As befits a premium lens there are seals and gaskets to resist dust and moisture. Flourine coatings on the front and rear lens elements make it easier to clean off dirt and smudges. (more…)


Fujifilm X-T2 Mirrorless Camera

camera

The new Fujifilm X-T2 promises photographers a realistic alternative to conventional dSLRs. The X-T2 is a mirrorless camera with interchangeable lenses that takes the viewfinder seriously.

The design of most mirrorless cameras ignores the viewfinder. Photographers have to rely on the rear screen to see the view through the camera’s lens.

Many camera manufacturers embrace the mirrorless camera philosophy for interchangeable lens cameras to reduce the cost of the camera. The reduction in camera body size and weight due to the removal of the reflex mirror becomes insignificant when a lens is attached.  The Fujifilm approach is providing a 21st century alternative to the mechanical system. (more…)


Aperture in Photography

Lens with the aperture at its smallest setting

The aperture in a camera lens is more than an exposure control. It also influences the Depth of Field (DOF) and the image quality.

The aperture is a mechanical diaphragm with movable metal blades that move to set the size of the opening in the lens. This controls the amount of light reaching the sensor or film so in partnership with the shutter speed and ISO, the image is correctly exposed.

The size of the lens opening is measured in f stops with seemingly meaningless numbers 1.4,  2,  2.8, 4, 5.6,  8 etc. Each of the steps in this scale indicates a doubling in the amount of light passing through the lens, as in changing the aperture from f5.6 to f4. Often lenses will also have in between f settings, especially at their widest opening, indicated by their smallest f-number. (more…)