Exercise: Tungsten and fluorescent lighting

Part one: establish the different light levels in a room lit by a tungsten light by metering at various points around the room.

Part two:  find a room lit with tungsten lamps and where the interior and exterior at dusk are both visible.  Take three photographs with varying white balance: auto, daylight and tungsten.

Part three: find two different interiors, each lit by a different type of fluorescent lamp.  Take photographs of each with the white balance set first to auto then to fluorescent.

We are now looking at available artificial light and the purpose of this exercise is to learn how two common types of interior lighting, tungsten and fluorescent, differ in colour temperature and how this affects the colour of the light of each.

Planning:

This was a bit of a nightmare to organise as it turns out that the lights in our house (which are mainly spot lights)  seem to be either tungsten flood or halogen, with the odd LED  one thrown in.

What happened:

I shot all the images in RAW in aperture-priority mode and using a tripod.  Apart from sharpening the images I have done no other post-processing.

Part one:

Part one asks us to take various meter readings in a room lit by tungsten lights.

Setting the camera on a tripod and using aperture-priority mode and an ISO of 100, I metered various points in the room including looking directly at an anglepoise lamp and also the darkest corner of the room.  Shooting wide-open at f/3.5 the shutter speeds set by the camera varied from 0.5 sec through to 3 secs.

Part two:

Part two asks us to take three photographs with varying white balance: auto, daylight and tungsten in a room lit with a tungsten lamp and where the interior and exterior are both visible.

I shot this series using an anglepoise lamp with a tungsten bulb.

Tungsten – auto white balance

Tungsten – daylight white balance

Tungsten – tungsten white balance Nikon

Tungsten – tungsten white balance Lightroom

The Nikon auto and tungsten images came out pretty similar, with colour temperatures of 3150K and 3000K respectively.  As I’ve remarked before in a previous exercise, the colour temperatures registered against a defined setting appear to differ between the in-camera values of my D7000 and those of Lightroom;  in this exercise, the tungsten setting is 3000K in-camera and a cooler 2850K in Lightroom.  I’ve shown the two images above.

Of the four images, the Lightroom tungsten, came out as more true to life both inside and out whilst the interior of the daylight image, at 5200K, is far too orange and the light at the window is too dark.

Part three:

Part three asks us to find two different interiors, each lit by a different type of fluorescent lamp.  Take photographs of each with the white balance set first to auto then to fluorescent.

For the first interior scene, I used the same room, but this time shot with a CFL bulb in the anglepoise lamp.

Fluorescent – auto white balance

Fluorescent – fluorescent white balance Nikon ‘cool white’

Fluorescent white balance – fluorescent Lightroom

My Nikon D7000 has a choice of seven fluorescent settings so I chose ‘cool white’ with a colour temperature of 4100K.  I also adjusted a copy of this image in Lightroom to the ‘fluorescent’ setting  of 3800K.  However, in this case I think that the image with auto white balance, with a colour temperature of 3100K, looks closer to real life although it still has a creamy-yellow tinge.

For the second interior scene I moved to the kitchen where there is a fluorescent strip light above our Rayburn cooker.

Fluorescent – auto white balance

Fluorescent – fluorescent white balance Nikon ‘cool white’

Fluorescent – fluorescent white balance Lightroom

Here, the auto white balance (4150K) is the best of the three images.  The Nikon ‘cool white’ (4100K with an increase in tint over auto) has a nasty purple tinge and the Lightroom fluorescent white balance setting (3100K), whilst an improvement, is a trifle cool with a hint of blue.  To be honest, none of the three images are really a correct representation of the scene.

Learning points from this exercise:

• Whilst different types of artificial light look pretty similar to the eye, they emit different colour temperatures and this needs to be considered by the photographer when selecting the correct white balance setting to use
• Fluorescent lights do not emit a full colour spectrum so photographic images taken under this type of lighting do not often look so pleasing to the eye
• My Nikon D7000 has seven different Fluorescent white-balance settings, ranging from sodium-vapour lamps (2700K) through to high temp. mercury vapour (7200K)
• The white balance option colour temperatures in my camera do not, in the main, correspond to those used by Adobe

Reflection:

I didn’t at first particularly enjoy this exercise as I don’t really like shooting indoors and I struggled to find the necessary lighting.  However my husband, as is often the case, came to the rescue with some lightbulbs for me to use.  Once I got going, I actually found it quite interesting  as it made me more aware of the shortcomings of the camera white balance settings and confirmed my current workflow of shooting mainly with ‘cloudy’ white balance and making any adjustments in post-processing.   I’m also really not sure that I want to faff around with seven different types of in-camera white balance modes for fluorescent lighting, assuming I can recognise each when I see it!

With regard to Part two, I think in hindsight that I could have chosen a better scene to shoot, showing a more balanced view of outside and inside.  However I have grasped the concept behind the exercise, which is what matters.   I’ve also realised how little I know technically about lightbulbs and the different types of light they produce so I will do some reading up here as I now feel woefully inadequate on this front (to be fair, this hasn’t been a ‘need to know’ issue up until now – as long as a light worked when I switched it on I was happy).