Blues Are Hard

I have gotten through my project of selecting 7 different picture profiles for my compact Sony camera. As related previously, I went down this rabbithole because the skies in the reference photos of the trees I’d sketch were tinged cyan (see the example at right). I am better off now after finding some good profiles, but Blues Are Still Hard.

To begin with historically, blue pigments have been very hard to come by. Taking one example, until it was synthesized by the chemist Christian Gmelin in 1828, ultramarine was only obtainable by laboriously preparing the mineral lapis lazuli sourced mainly from Afghanistan. (I should read science writer Kai Kupferschmidt’s book from 2021, Blue: In Search of Nature’s Rarest Color).

Next, in summertime here the skies are blue with nary a cloud to be seen for months at a time. Photographically this becomes a challenge because if I’m exposing on a street-level subject, the skies will tend to be overexposed and blown-out. This is not what the eye sees, since the eye-brain has a much higher dynamic range than any camera. In other words, our visual system is quite capable of taking in a bright blue sky together with details in shadows underneath shrubbery at the same time, but cameras cannot handle this.

I sketch using either watercolors or watercolor pencils as my color medium. Here is a different problem. Consider a scene where one is looking through sunlit leaves up into a bright blue sky. The leaves may end up having a lighter value than the blue sky because they are transmitting direct light. This is really hard to paint in watercolor – one can’t do a uniform blue wash for the sky without laboriously masking out the leaves, and then painting the leaves a very light yellow green. Photographing such a scene isn’t much easier because of aforementioned dynamic range problems.

At least I’ve worked out that the best pigment for painting Northern California skies is cobalt blue. This doesn’t necessarily hold for other places in the world.