TAOP - Light - Exercise Tungsten and Fluorescent Lighting

At the beginning of this exercise we are asked to find  a room fairly brightly lit by tungsten lamps and to wait until just after sunset. The exercise asks us to switch the lights off, allow time for our eyes to adjust to the light from outside standing close to a window and then turn back on the rooms light.

We are asked to judge what colour the light is and see if the light becomes less coloured after a minute or so. Performing this "test" I notice the light in the room appears very warm, an almost orangey colour. And yes, after a few minutes my eyes seemed to adjust to this and the light in the room becomes more used to the colour I normally experience walking in and out of the room  during an evening.

Doing some quick research on the Internet I find the following about tungsten light:

 - colour temperature is measured in degrees kelvin (I recall this from my old school days). I know from previous exercises that this is not the temperature of the light emitted but is the distribution of energy in the lights visible spectrum

 - a tungsten light bulb is created by running an electric current through a tungsten filament. The filament then glows and light is produced

 - From previous exercise I know that different kind of light can be balanced in different ways. To balance tungsten light to make it appear like daylight a blue correction gel can be used. This may be very important in flash photography. If you want to balance light to appear like tungsten you would use an orange gel

 - tungsten has a colour temperature of 3200 degrees kelvin

Exercise 1

Compose a photograph in a room where light outside is at dusk and appear level.

For this exercise I've used the same RAW file image  and have adjusted each one using white balance. I've taken the images at close to 9 pm in the evening in the middle of June

I did have to boost the ISO so I could get a faster shutter speed so I could avoid camera shake. I could tell from the slow shutter and shutter speed set by the camera I would have camera shake. Looking at the resulting image on the camera screen also confirmed this, as did the histogram, I was already using the widest aperture I could of f/8 for my ultra wide angle lens. I would also add that there are 6 ceiling mounted tungsten lights each around about 50 watts

Image 1a

This image has the white balance set to as shot. The light bulbs can be seen to appear to be giving out white light but the effect in the room is one of warming. I think this was the colour my eyes originally saw when first switching on the lights before they adjusted

Image 1b

This image has the white balance set to daylight and when making the adjustment I could see the image taking a warmer, more orangey change compared to the one above

Image 1c

White balance set to tungsten. Wow - What a big change. This certainly wasn't the colour or should I saw temperature of light my eyes saw but is much more realistic to the light I would normally see in this room before I have switched on the lights

Image 1d

White balance set to auto is very similar to the one above where the white balance is set to tungsten

Exercise 2

For this exercise I have taken an image in two rooms, both lit by types of fluorescent lamps or bulbs and applied to each of the RAW images an auto setting and a fluorescent white balance setting.

Image 2a

Again I've boosted the ISO so I get a fast enough shutter speed to avoid any camera shake and I've left the image with the as shot  white balance. This very close to what I saw with my eyes. The fluorescent bulbs give out a very warm yellow colour. The walls look yellow where as they are really a cream colour as can be seen below with the white balance adjusted.


Image 2b

This is the same image as above except I've adjusted the RAW file white balance to the fluorescent setting. There is a big difference between the un-adjusted image above (2a) and this image (2b) in that this image does not appear to have the yellow colour cast and the scene much more natural looking.

Image 2c

The auto adjustment in this instance appears to have darkened the image which is in contrast to how the auto white balance setting changed the result in image 2f below


Image 2d

A common theme again with the ISO set to around 850 prevent camera shake in the dim conditions. This image has the white balance set to as shot. The warming yellow of the light bulb can be seen clearly colouring the bright white ceiling and walls

Image 2e

Using the Fluorescent white balance adjustment the true colour of the room can be seen and the yellow warm cast of the fluorescent light appears to be removed. 

Image 2f

However with the auto adjustment the colours seem even cleaner and without colour of the bulb light.

Its noticeable that this is almost having the opposite effect of using the cloudy white balance option which adds a warming colour cast to the image

Setting the white balance to Auto in most cases appears to make the correct adjustment e.g. is very similar to setting the white balance to make the specific adjustment understood to be required by the photographer. However image 2c appears to be instance where Auto doesn't quite make the correct change...at least in my opinion.