in Cameras, Film

What is light, anyway?

I expect that better writers and philosophers than me have explored what it is that photography teaches us about perception. Certainly it is teaching me that light is not perception. First of all, with black and white film, I had to reconcile the difference between what I was seeing with my eyes when taking pictures, and what actually came out in the negatives. It’s hard to recognise how much levels of light really vary in the real world when just looking at things – eyes, after all, are very well suited to looking at things in all levels of light where there is any at all, and also many different levels of illumination in the same scene.

For instance, I am currently indoors in a not terribly well lit bar, but I can easily see everything around me. If I concentrate, I can tell that I have a lower depth of field here than I would in daytime, and that my eyes have to adjust slightly to see things at different distances. But I have to concentrate to notice that. There is probably 1/1000th of the light in here now than there would be outside in full daytime, but that doesn’t matter to me in practice, except if I am taking photographs, when it suddenly matters a great deal.

There is also the issue of colour. Most of the light here is very yellowish, but I adjust for that pretty well – I instinctively know that the menu by the candle is white, not yellow, and that the plant on the other side has green leaves. When there is more light and the difference is more subtle I barely notice the ambient colours. On the other hand, here are two versions of the same shot taken on Elite Chrome 100 in downtown LA recently.

Note that this is slide film, so there aren’t any of the odd issues regarding colour correction that you get with colour negatives. But the uncorrected picture looks very blue. I googled to see whether this was a known issue with the film (several others from LA at the same time have the same) and saw some people saying “yes, shadows are blue with Elite Chrome” but then also others saying “but shadows are blue in natural light – they’re lit by ambient light from the blue sky, not from the sun”. From my memory, the second picture is closer to what I remember, but look at how the white balance correction in the second picture also removes a lot of the blue from the sky, which really have should stayed. And, you know, it was pretty monochrome in the shadows. Perhaps it did look like that and I’m misremembering?

What helps me get past this sort of rumination is remembering that the point of taking photographs is to produce a good picture. Maybe the camera and film will capture colours and light in a way that won’t correspond to what I remember seeing, but that’s okay – what matters is knowing how they will capture the scene given the settings I choose, what sort of results I want, and matching the two together.

  • Paul Vigo

    As frightening as it is, HDR photography captures the way the eye sees light better than traditional film. The HDR process (by combining multiple exposures and varying local contrast) treats each point in the picture as a smaller exposure, and adjusts EVs and color balance accordingly. Your eye does much the same thing. 

    When we view overbaked HDR, the artefacts of this process become obvious. Yet when we view a scene with our eyes, such effects exist, but are adjusted dynamically, so we don’t perceive them. (Fringing effects aside) HDR images will read better to our eye if they fill our entire field of vision. If we view them from a distance, local contrast adjustments act with a finer fidelity than our own visual apparatus and thus become apparent. 

    Before digital, the HDR process was practiced in the dark room. For single exposures, dodging and burning could extend dynamic range +/- 2 or 3 EV. Push and pull process techniques could squash and stretch dynamic range to place contrast in un-natural, but more natural looking ranges. In the case of static subjects, such as landscapes, bracketed exposures could later be re-combined. Ansel Adams was known for spending up to a month in the darkroom achieving such effects on a single image. Our eye reads these images as closer to nature, though they are in fact more artificial.

    The eye tricks us about light routinely. Photography, by objectively revealing the light in a scene, shows us how subjective our visual systems are.  

  • ordinal

    I do use HDR occasionally but it is a little impractical for street photography. Thankfully it is quite easy to drag out shadow detail from scanned B&W film – but I’m always surprised how often it’s necessary to do so just to get vaguely “real-looking” pictures. At least one doesn’t then have to worry about colour as well.