In this tutorial we started by looking at light, which I was looking forward to. Learning how to white balance felt like the last missing piece in my understanding of basic camera operations. However, I also learned that white balancing isn’t all that useful. This is because it’s easier to keep the shots consistent, and then make any desired changes in post (I adjust colour temperature and green/pink balance in my work as an editor all the time).
We started our investigations into colour temperature by first learning about the terminology and background knowledge.
Traditionally there has been 5600 K (kelvin) film for use in daylight, and 3200 K (kelvin) film for use with incandescent lights.
This is fairly confusing because kelvin is a measure of temperature, like Celcius. But when the kelvin increases, why does the light colour get more blue? Blue is a cold colour! It became apparent to me that there were a few things going on here that were working in the opposite way I’d expect them to, and the Wikipedia article for Color Temperature refers to these apparent contradictions multiple times:
“The fact that “warm” lighting in this sense actually has a “cooler” color temperature often leads to confusion.”
“…blue occurs at higher temperatures, whereas red occurs at lower temperatures. This is the opposite of the cultural associations attributed to colors, in which “red” is “hot”, and “blue” is “cold””
According to this Wikipedia article, what we’re measuring in kelvin when we’re talking about Colour Temperature is the “radiated heat flux” of an incandescent bulb. So an incandescent bulb which is running at low power and is literally cool to the touch will look very orange, and have a low kelvin measure.
An incandescent bulb which is painfully hot to touch will look white hot (moving towards the blue side of the scale when compared to the underpowered bulb), and will have a higher kelvin measure. I can see this very clearly in the two brightness settings on my bedside table’s lamp.
To me it makes sense that the sun, which is significantly hotter than an incandescent light bulb, will have the hottest kelvin rating. The sun’s light does look blue when compared to incandescent bulbs, especially upon stepping outside into a bright day after being inside with just artificial lights for a while. It also feels natural to me that the blue flames on a stove are hotter than the orange flames.
All this means that the kelvin rating of a camera setting or film stock is referring to the kelvin of the lighting that it should be used in. It also means that this camera setting or film stock will be “shifting” the colour temperature in the opposite direction to compensate for this coloured light, bringing the whites to a more true white. I made this table to clarify this:
This leads to a fascinating case of two wrongs making a right. When I found that 5600 K film is film that makes an image’s colour temperature look warmer, I mistakenly figured that a higher temperature in kelvin marked on the film or camera setting is suggesting a greater “warmth” that this film or camera setting brings to the image. I was right for the wrong reason!
The last thing I’d like to find out is why we naturally think that blue looking scenes are cold, and orange looking scenes are hot. In class Robin showed us a clip from a film which looked very blue, which was meant to show (and did show) that the scene was very cold. But based on my findings so far, the bluest light would come from the brightest, most sunny day! A cold day should look orange! This distinction goes strongly against my intuition which says that hot days are orange and cold days are blue. This confusion is clearly demonstrated in the google images results for “hot weather” and “cold weather”.
On my own, I figured that our eyes adjust incredibly well to bring the colour temperature of any light source to a neutral level. On top of this, because we associate heat with orange (because of the sun and fire), and cold with blue (because of snow and water), we just feel like a blue world is a cold world and an orange world is a hot world.
After talking to Robin about this, I found out that the reflections from the ground and other objects also contribute to the colour temperature of an environment. Because snow is white, it reflects a great deal of additional light, making the colour temperature of a scene more blue! So the ski mountains I’ve been to really did look blue, it wasn’t just in my head! And that must be why ski goggles often have an orange filter on them!
Finally, I realised after this class that nothing ever “is” a certain colour. Colour is just the way light bounces off something. If a pair of pants look one way in a change room and another way outside, it’s not like the colour we see outside is their “true” colour. It’s just the colour we see in that particular light. With this in mind, I can see why getting a “correct” white balance all the time is unnecessary.
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