Chiaroscuro helps me to think of light in terms of intensive differences and gradients, the intensive contrasts of light and dark that attract our eye, and the gradients of light and shadow upon which they move. Everything is a matter of intensities and thresholds—both in the light and in our system for perceiving it.
There’s an assemblage in play: Intensive Differences in Light—retina—optic nerve—other neurons. This starts, ultimately, with the sun, then the scattering of light that attracts my eye, the way the light registers upon the camera sensor. Then the light of the computer screen interfacing with my brain as I process the image in Photoshop. And then back into electrons, the web, and the screen before you. Everything is intensities and thresholds, triggers in different screens and different brains, light moving at differing speeds to effects I can’t foresee.
Anyway, that’s what I’m trying to see lately: to attend less to the object I’m shooting, and more the intensive differences in the light, and especially, to the gradients between light and dark. Deleuze, of course, set me up for this. Here’s a passage from “The Three Ethics” where he discusses chiaroscuro:
We must also understand “effect” optically and not merely causally. Effects or signs are shadows that play on the surface of bodies, always between two bodies. The shadow is always on the border. It is always a body that casts a shadow on another. We know bodies only through the shadow they cast upon us, and it is through our own shadow that we know ourselves, ourselves and our bodies. Signs are effects of light in a space filled with things colliding into each other at random. If Spinoza differs essentially from Leibniz, it is because the latter, close to a Baroque inspiration, saw the Dark (“fusIcum subnigrum”) as a matrix or premise, out of which chiaroscuro, colors, and even light will emerge.
In Spinoza, on the contrary, everything is light, and the Dark is only a shadow, a simple effect of light, a limit of light on the bodies that reflect it (affection) or absorb it (affect). Spinoza is closer to Byzantium than to the Baroque. In place of a light that emerges by degrees from the shadow through the accumulation of red, we instead have a light that creates degrees of blue shadow. Chiaroscuro is itself an effect of the brightening or darkening of the shadow: it is the variations of power or vectorial signs that constitute degrees of chiaroscuro, the augmentation of power being a brightening, the diminution of power, a darkening.