On respecting the natural state of things, by legendary photographer Henri Cartier-Bresson: “It is essential, therefore, to approach the subject on tiptoe - even if the subject is a still-life. A velvet hand, a hawk’s eye - these we should all have. … And no photographs taken with the aid of flash-light either, if only out of respect of the natural light - even when there isn’t any of it. Unless a photographer observes such conditions as these, he may become an intolerably aggressive character.”
To deny myself the convenience of flash lighting in a photograph, even when there is no light! Cartier-Bresson would rather that I lose the picture than use a technique that is so disrespectful to natural light. Using a flash in darkness, I may get the picture, but I’ve taken it by force, impatiently. And, perhaps I have violated a natural law, in the same way that artificial light has virtually eliminated the natural human rhythm of sleep-when-the-sun-goes-down and rise-when-the-sun-comes-up.
For the creative photographer who chooses with a purpose, flash-light now has the effect of invoking a photojournalistic quality (in which the flash is required to catch a fleeting, news-worthy moment). But it is not a natural quality; is not at all the way we see people. Natural light is three-dimensional and alive. It comes from multiple sources: the sunlight that shines on the left side of our subject also reflects off of other surfaces in the space, creating a complex interplay of light - a world of light. Flash-light principally shoots directly from the camera into the face of our subject like we are the source of illumination and they are the victim of a kind of egocentric, photographic super-nova. The flash forces the camera itself to become the source of light–an unnatural arrangement. Subjects become two-dimensional and evenly, eerily lit, without shadows to give depth … only a sharp black line along one edge to indicate the offset of the flash from the lens.
It reminds me of one of the ways that fighter pilots gain the advantage in a dogfight, by getting between the sun and their adversary. The sunlight blinds the other pilot, who will not be able to see the aggressor in the glare. Flashes on cameras have a similar effect, that of disorienting a subject and putting them on the defensive - after the POP of the flash, the subject blinks and staggers, waiting to adjust to the dark again. If the photographer were a spy, taking a portrait of their enemy, now would be the moment to strike.
Where a photograph taken in natural light can be like a gift given by the subject with the help of the sun or lamp, and received by the camera on behalf of the photographer, flash-light is something more like the artistic version of an act of overwhelming force.