While its not a new technique, the idea of underexposing your digital images to maximize dynamic range in your processing has been catching on heavily over the past couple years. Its like HDR but more natural looking and without crappy halo effects riddling your subjects. Oh and you don’t need to use 3-6 shots to combine in post either. One shot, easy peasy.
There’s plenty of pros and hobbyists out there using this technique already, so this article are for those others who haven’t come across this tasty morsel yet. Here you go.
First off, maybe you don’t know what dynamic range even means. Lets tackle that first. When you look around this amazing world, your eyes focus on different parts of a scene, a continuous flow of photons bounce into your retinas, and your brain stitch these seamlessly into an ever moving motion picture via chemical reactions. The most visual data comes from our central visual field (why your peripheral vision is blurry and vignetted). As you move your retinas around a scene, you might come across one part of that scene that is much darker or much brighter than the rest of the scene, and your pupils adjust instantaneously and usually unbeknownst to you. Essentially your eyes and brain create an illusion that everything in that scene is properly exposed with detail in both the highlights, midtones, and shadows.
However, when you take a photograph with your camera, you have to choose if you want to expose for highlights or for the shadows. While everything in photography and art is subjective, a “good exposure” should show proper detail depending on what you want the focus and/or the tone of the image to be. Maybe you want a properly exposed face for a headshot, or maybe you want an artistic silhouette against a sunset.
In evenly lit scenes, its kind of a no brainer – you expose until your subject or main focus of your photo has detail. But we live in a world of heavy contrast, that is to say, scenes with a wide gamut of shadows and highlights. One portion of your scene might be getting blasted by the sun and the other part of the scene might be heavily shaded by trees or a building. How do you choose what to expose for?
Many photographers will still choose to expose for the primary focus of a scene, whether that’s your subject for a portrait or a tree on a hill. Its safe, tried and true. The reason being is that up until the past few years, camera sensors in professional DSLRs were not capable of recovering details in the shadows of images without significant digital noise being added. It looked like garbage. Recently however, camera manufacturers such as Nikon and Sony are creating sensors that enable perfectly clean images when recovering shadows in post production editing. Add a noise reduction filter from your editing app of choice and its truly incredible results.
Back to Dynamic Range. We measure DR by f stops or EV. Depending on how much difference there is between the black/shadow values and the white/highlight values, you can say that for a given scene, it has x number of f stops. An evenly lit scene might only have 6-8 stops of range between the darkest value and whitest value. A more contrasty scene might have 12-14 stops of exposure.
Your eyes are incredible organs. Pair that with your brain, and you can interpret a scene with excellent detail that has 10-14 stops of dynamic range. In comparison, your iPhone or compact camera has at most 8 stops of DR. Add the fact that they don’t shoot RAW and only save compressed JPEGs with far less data to them, then you see why you often lose detail in either the shadows or highlights of a contrasty scene. DSLR cameras usually fall into the 8-11 stops range, while Hollywood professional video production cameras such as RED and Arri Alexa can expose for 14 stops latitude. Thats as good as the human eye!
But back to our cameras. Ok, so we can get 8-11 stops from our DSLRs. Sweet. We can work with that. In fact, we can make it even better.
Lightroom is an incredible editing application that utilizes all the information in your RAW files and lets you manipulate it in an infinite number of ways. One magical way is expanding that DR for your scene in that image and recovering detail in the shadows and highlights. In digital photography, it is always easier to recover details in shadows than highlights. If you overexpose a shot, and burn your highlights, then tough luck, you can try and pull your highlights back, but you’ll be left with a yellowish faded cast on the highlights. Shadows on the other hand recover much better. There might be noise and banding, but at least there’s detail to see. So the golden rule in this technique is to always expose for your highlights and not your subject. In my example above, I exposed for the clouds in the sky. Essentially my straight out of camera (SOC) was nearly black. But using Lightroom, I can recover all those shadow details, without any noise or artifacts, AND keep detail in my highlights. Had I tried to expose for my subjects, then I would have lost much of the detail in those clouds and sky in post.
There are some caveats to know when underexposing your shots, so ill list them here: