Using flash, part 6 - flash colour temperature

Light from flash units is typically balanced for noon daylight (5600K) - if this means nothing to you then check out an overview of colour temperature at ePhotozine. Summer sunlight from 9am to 3pm is in the range 5400-5700K, so using your flash as a fill-in light during this time leads to a good mix between ambient and flash light. When you use your flash indoors and capture ambient light produced by tungsten lightbulbs (2800K), however, it's impossible to adjust the white balance of your shot correctly for both light sources. If you set the white balance for the flash light, the ambient light will appear orange, setting correctly for the ambient light means the flash light will appear blue. To overcome this you can adjust the colour temperature of your flash using filters - I purchased a great selection from FlashGels.co.uk. The picture above shows three types of filter: colour temperature orange (CTO - for cooling the flash light to balance with the light from tungsten lamps), colour temperature blue (CTB - to warm the flash light) and plus green (adds a green cast to balance with fluorescent lighting). These can be attached to the flash unit using velcro, but having watched Blue Peter during my formative years, I'm naturally a dab-hand with cardboard, double-sided sticky tape and scissors (provided an adult is available to supervise me) and so constructed a filter mount. 

A relaxing interlude

Having a hectic evening but didn't want to disappoint my readership (Chris, your support is very much appreciated!) A calming shot of a flower to soothe fevered brows...

Using flash, part 5 - portrait photography

A photograph of my daughter's first encounter with a bubble! Click this link to see further portraits and my portable studio. Two Canon 580 EX Speedlites were used to light this scene, one fitted with a homemade snoot (a device to limit the spill of light) to light the bubble, and the other fitted with a Lastolite EzyBox softbox to illuminate Emily. These were controlled wirelessly by a Canon ST-E2 transmitter which allows full control of the lighting ratio. I've made a range of flashlight modifiers, primarily inspired by the terrific Strobist blog, and will discuss these soon.

Using flash, part 4 - wedding photography

When you take a photograph using flash you get to make two creative decisions about exposure - how much ambient light do you capture and how much flash light do you add. You get to control both of these factors independently through under- or overexposure. The above photograph was taken at Chris and Sue's wedding last week in Folkestone. It was taken in aperture priority mode with -1 stop of exposure compensation to keep some colour in the sea (pity there were no clouds) and with -2/3 of flash exposure compensation to tone down the fill-flash effect. How did I arrive at these values? I let the camera take its best guess for the first shot, checked out the LCD screen and histogram, and then made the necessary adjustments to balance the two light sources. 

Using flash, part 3

So, if there's no suitable surface for bouncing your flash off, or you're outdoors, what do you do? One solution is to bring a surface with you, as shown in the photo above.

To construct this flash-modifier I followed Chuck Gardner's instructions on his 'Photography and Lighting for the Thinking Photographer' website. It increases the effective size of the flash over 10-fold, loses little light, weighs next-to-nothing and is readily assembled

I still have materials left to construct more of these (for a small fee) - if you're interested please get in contact.

Using flash, part 2

The effective size of the light source is the most important factor in lighting a subject as it determines the type of shadows produced. Bouncing flash is a simple way of increasing the size of the light source and reducing the contrast between light and shadow - referred to as 'softening' the light. An ideal surface for bouncing flash will provide diffuse (same brightness regardless of viewing angle) rather than direct (as from a mirror) reflection and will not impart any colouration to the light. Another consideration is distance to the surface, as the resulting light intensity will be inversely proportional to the square of the distance.

In practice this means that it's not always easy to find a suitable surface for bouncing flash - it's either too far away (large loss of light), too close (light not sufficiently softened), too reflective (light remains hard), too coloured (light is also coloured) or features shadow-casting objects, such as chandeliers and moose heads! Also, what can you do outside, when there are no surfaces at all?

Read my next post to find out.