It occurred to me recently that I am part of the last generation of photographers who grew up shooting film. The first SLR I ever owned, back in the early ’90s, was an old Pentax K1000. It was rugged, reliable, and a fantastic learning tool. It had a little analog light meter – a tiny needle that you could see at the edge of the frame, when you looked through the viewfinder. If the needle was in the middle of its range, the scene was, supposedly, properly exposed.
I quickly learned that framing a scene and shooting with the needle in the center resulted in “thin” negatives with very little detail, which meant dark, grainy photos. What you had to do was find a shadow on the ground, meter for that, and then shoot the scene. Because film held far more detail in the brights than in the darks, when the photos were printed, they would look good. We called this “exposing for the shadows, printing for the highlights.”
Digital media is somewhat different from film. Although it does tend to hold more detail in the brights than the darks (hence the frequently-heard advice to “push your histogram to the right”), information that would have been captured in the highlights of a film negative can be “clipped” from the digital image. In other words, once you get to 100% brightness for whatever format you’re shooting in (obviously, RAW formats have much more latitude than compressed formats), the camera’s computer just clips the information to 0. A good camera will make the roll-off from bright to pure white look smooth and natural. A lousy camera will color-shift it and give the highlight a ragged white edge. In any case, you’re more likely to be able to pull up some kind of data from the shadows than you are from overexposed highlights, unlike film which captures great detail in bright areas, but falls off to black quite readily in shadows.
All of this is a roundabout introduction to a very well-thought-out chart by crewofone reader Marc Drago. I could have used this back when the light meter in my K1000 quit working, and I had to guesstimate exposures for everything. Although Marc was inspired to create this diagram after buying a light meter that only gave readouts in Lux or Foot Candles, I suspect that, with the immediate feedback of the LCD viewfinder, most readers will find this to be more of a useful reference to help understand the relationship between F-stop and ISO in different lighting situations. This is designed for video shooters, so this chart is based on a constant shutter speed of 1/50. Marc has kindly offered this under the Creative Commons NC attribution license – which, as he describes it, “means they are essentially free for everyone but they can’t be sold; in the hope that others might gain use from them.”
Many thanks to Marc for creating this reference, and sharing this so freely. Marc has two films in the works right now, so I look forward to hearing more from him!
Download the PDF here.