TAOP: Part 4 – Light: Exercise – Tungsten and Fluorescent Lighting
April 3, 2012
The first part of this exercise instructs me to look out of a window at dusk for around a minute before looking at the interior of the room, lit by tungsten (so, normal, indoor) lights, and note my observations. I did this a few days ago when the weather was better than it is tonight!
On the first instant after looking back into the room it appears to be a very orange-yellow. On looking back outside the outdoor light appears much paler and cool – with a tint of blue.
The second part of the exercise was to measure light levels at various points around the room – noting whether, at full aperture and ISO 100, the shutter speed would be fast enough to shoot hand-held. The range of readings under the interior lights was from 0″3 seconds where the lights are dimmest, to 1/20 seconds where the lights are brightest; which is only just fast enough to shoot by hand, so long as there is no motion in shot.
The third part is to take three identical pictures where the tungsten lit interior and exterior at dusk are both visible.
The first with white-balance set to auto:
The second with the white-balance set to daylight:
And the third with the white-balance set to tungsten:
In the first two the foreground appears orange-yellow (more so with ‘Auto’) while the landscape behind appears normal. In the third, the wall and background appear very blue (particularly the landscape) while the window appears closer to white. While the tungsten setting has eliminated the yellow I think the blue-ish tinge comes from the daylight outside – so the setting hasn’t been able to correct for there being two different coloured sources of light.
The final part is to take two different shots under fluorescent lighting – and of each shoot with the white-balance set to Auto and then to Fluorescent.
In the “Auto” shots the images appear warmer. Set to fluorescent the images appear pale and flat.
As the exercise concludes, fluorescent lamps do not emit a full colour spectrum.