Part 4: Light – Exercise 3 and 4: Judging Colour TemperaturePosted: October 14, 2011
Part 4 : Light
(Project – The colour of light)
Exercise 3 and 4 : Judging Colour Temperature
I was interested to read about the colour of light. Mainly because I have never thought of light in that way as I think more in terms of bright, misty, gloomy and dark. I have certainly not thought of sunlight as being colourless or ‘white’. To my eyes when the sun is very bright everything looks ‘washed out’. I suppose it’s the same thing with different terminology. I certainly know now when it isn’t a good idea to take particular photographs because of the quality of light. How is it though that bright sunlight on a day in England ‘washes out’ colours and leads to risk of highlight clipping whereas that happens much less often in the Mediterranean countries for example?
I own more than one camera and can also see how the different cameras produce images with slightly different colouring. My Canon seems to produce images which are warmer and more earthy in tone whereas my little Ricoh produces images which have more of a blue tinge. I’m now thinking that must be due to the way in which the different sensors capture the quality of light. I understand about wavelengths and the scattering of light as I’m reading it but my mind keeps resisting the explanation. I like the sky to look blue. It makes it more vivid and immediate than seeing it as scattered wavelengths. Still I now have an explanation for my grandson when he asks, “Why is the sky blue?” – a question that most children seem to ask at a certain age.
My Canon 500D has 7 seven standard white balance settings. I looked at the manual but this doesn’t give me the actual colour temperature settings for each one so I looked on the web.
- Auto White Balance evaluates the scene and decides the most appropriate white point. The system can be fooled if there is an abundance of one colour or no actual white for the meter to use as a reference. This results in an image with a colour cast. I’m thinking that this could well apply to landscape photography, particularly in Spring and Summer.
- Daylight – for bright sunshine with a balance for a colour temperature of around 5,200K. this is slightly cooler than noon sunlight but works best for the greatest part of the day.
- Shade – the colour temperature is higher (bluer) and usually around 7,000K. Setting most suited to areas of light shade rather than very heavy shadow.
- Cloudy or hazy – sets a colour temperature of around 6,000K and best used on days when the sun is behind the clouds, creating a very even and diffuse light.
- Tungsten – assumes a colour temperature of around 3,200 and suitable for most tungsten lamps normally emitting a yellow light.
- Fluorescent – set for around 4000K. However there are six types of fluorescent light, each with a different temperature. They also emit an interrupted spectrum with peaks over quite a wide range and also change over time, gradually altering the colour temperature of light they emit.
- Flash – is a very white light with a colour temperature around 6,000K.
There are two further settings which give total control:-
- Custom white balance – you tell the camera which area in the scene is supposed to be white.
- Kelvin – You set the colour temperature in degrees Kelvin and may be the best setting to use if you have a separate colour temperature meter. Test shots will be needed to calibrate the colour.
I’ve been shown how to set custom white balance but it hasn’t sunk in yet! It’s a relief to know that, in most photography, there’s no need to be exact about colour temperature and it’s enough, “to know when the light is not white, and if only by a little or by a lot”. (p. 114 Handbook.) I mainly use auto white balance but sometimes I have switched the white balance setting. I’ve also altered it in Photoshop using the white balance dropper in ACR and/or altered the temperature and tint sliders.
Three photographs of the same subject, at different times of the day and using the daylight white balance setting.
No. 1: Full sunlight during the middle of the day
f/8 1/60 ISO 100 Taken at 1.26pm
No. 2: Shade in the middle of the day
f/8 ¼ ISO 100 Taken at 1.29pm
No. 3: In sunlight when the sun is nearer the horizon
f/8 1/6 ISO 100 Taken around 6.20pm
Image No. 1 is the purest in terms of colour and I can see how the fountain gets bluer as the days goes. The grass looks much greener as well – almost unreal. I can’t see any orange in image No. 3 though. I’ve checked the colour temperature which is 4900 K for each of the images which is the daylight setting temperature on my camera and so slightly less than 5,200K.
Three further images at the same times of day but varying the white balance setting – daylight, shade and auto.
Full sunlight during the middle of the day (around 12.46pm)
Slight noise reduction and sharpening used.
No. 4: Daylight WB (4900K)
No. 5: Shade WB (6350K)
No. 6: Auto WB (4200K)
The statue had the sun shining full onto it and the shadow at the back is from a small tree which is behind and to the right of it. At Shade WB the image is too yellow. There isn’t a lot of difference between No. 4 and No. 6 and I can’t decide which one I prefer. These images were taken on 2nd October and I decided to experiment by using a similar image taken on 16th September, around 1.26pm, using Auto WB. I altered the settings to daylight and shade WB in ACR:-
No. 7: ACR Daylight WB setting in ACR
No. 8: Shade WB setting in ACR
No. 9: Actual Auto WB setting in camera, which evaluated at 4750K)
f/8 1/15 ISO 100
The sun was higher in the sky and the time a little earlier but this gives similar effects to the earlier images which had settings in camera. Does this mean that I might just as well use the Auto WB setting in camera and then change the settings in Photoshop?
Shade during the middle of the day – taken around 1.45 pm
I chose this scene because it was certainly in the shade, of the tree, and the playground behind was in full brightness of the sun. Also we have the colours in the playground, wood-tones and earth tones.
No. 10: Daylight WB 4900K
f/8 1/80 ISO 200
No. 11: Shade WB 6350K
f/8 1/60 ISO 200
No. 12: Auto WB 4600K
f/8 1/60 ISO 22
As before, the Shade WB (No. 11) gives a more yellow hue, which I don’t like. I can see more blueness in the earth on Auto WB.
In sunlight when the sun is close to the horizon
This was around 6.20pm on 26th September and the sun was beginning to set low on the horizon. Carters’ Steam Fair was visiting and we went along to take some photographs. The fairy lights on the rides etc were also beginning to compete with the low sun. All images were f/8 @ 1/40 ISO 100.
No. 13: Daylight WB 4900K
No. 14: Shade WB 6350K
No. 15: Auto WB 5700
I can’t see too much difference between the three.
As we went around the Fair I experimented with the settings. One was taken from low down and so I used the Shade WB setting.
No. 16: Shade WB 7500K
f/11 1/40 ISO 200
I did some editing on this to lighten it and also bring more attention to the dog’s tail.
As it became darker the lights became more evident. I used Fluorescent WB on this one and also aimed to show up the steam against the sky.
No. 17: Fluorescent WB 3800K
f/8 1/60 ISO800
What’s clear is that Auto WB does evaluate the scene and so sets varying points on the scale whereas the different settings seem more standardized. In this respect my first point of call would always be Auto WB unless there were special circumstances. – such as in studio photography and, maybe, landscape where there is a predominance of one particular colour. I was also interested to see whether the WB setting might have an effect on the exposure setting but it doesn’t really seem to.
14th October 2011