“Dynamic Range” in photography refers to the ratio between the two most extreme values of light within an image. This is from the lightest to the darkest tones. So the “dynamic range” of a photograph is the difference between pure white and pure black. The term is also used to describe the “dynamic range” a particular camera has. Dynamic range is important to understand in photography to ensure you know the limitations of cameras and to make sure that your photos are correctly exposed. This quick beginners guide should help you understand the basics of dynamic range in photography.
Limitations in cameras
The dynamic range of a camera is measured in what are called “f/stops.” The brightness level of the camera doubles with a one-stop increase. Human beings can see about 20 stops, and a top of the range camera has about ten stops, 14 in some of the really high-end cameras. This means that the human eye sees a much more comprehensive range of tones.
For example, if you have ever taken a photograph on a sunny day and the photo has turned out nothing like what it looked like to you, you’ve experienced the limitations of the dynamic range of the camera compared to the human eye. But remember this is not your limitations as a photographer, it’s the limitation of the technology you are using.
The dynamic range of screens and printers is even less than that of a high-end camera. So, even if your camera can capture a high number of stops, you may have to edit the image to translate the dynamic range to that of a screen.
An example of a situation when the photograph doesn’t do the real scene justice in terms of tonal range. There are also areas that are underexposed on the rocks and overexposed in the sky.
Understanding the impact of dynamic range
As a photographer, running into dynamic range issues is something inevitable, but you get better at addressing the problems the more you come across them. If the dynamic range of the subject does not exceed that of the camera, your photograph will be correctly exposed. If the range is extensive, then it will affect one part of your photograph, and it will be under or overexposed.
When the dynamic range of the subject is broader, you need to choose where you want to lose detail, in the highlights or the shadows. Generally, it is better to expose the highlights so that they have more detail and sacrifice the details in the shadows as often you can recover these in post-production better than highlights.
Thankfully, there are techniques you can use to lift shadows like using a fill-in flash or lighting up the areas using a reflector. You can also invest in graduated neutral density filters (GND) to help balance out the dynamic range in some scenes. These filters are essential in say landscape photography where you often face a broad dynamic range. Below are some of the techniques you can use to ensure you get a better dynamic range in your photos.
The highlighted red area is overexposed and completely white. A GND would be useful in this type of scene.
Graduated neutral density filters
One of the major challenges when photographing landscapes during what is the best times of the day (early morning or late afternoon) is that the sun is low in the sky. Often this means you are faced with a bright sky and a dark foreground. This is one of those scenarios where the dynamic range of the scene might be too much for your camera. If you expose for the sky your foreground will be underexposed (too dark). If you expose for the foreground your sky will be overexposed (too bright).
In this scenario a GND filter is placed in front of the lens and can be rotated to reduce the brightness of the sky, allowing you to expose more of the shadows while darkening the sky. These filters come in a range of different strengths that can reduce the brightness of the sky by around three f/stops. These filters have a dramatic effect and are the quickest way of matching the dynamic range of the subject with that of your camera.
HDR Photography
One way of overcoming problems with dynamic range is High Dynamic Range (HDR) Photography, where you take the picture at multiple exposures and then combine the images into one final composite in post-processing (some cameras have an HDR setting that does this in-camera for you).
For this type of photography, a tripod is essential if your slowest image of the range is going to be at a slow shutter speed. A tripod will also ensure that you take the same image and there is no movement. If your camera doesn’t have HDR mode, you will need to set your camera on manual and then take the multiple shots adjusting your exposure from underexposing to overexposing.
Make sure you don’t adjust the aperture as the depth of field will be altered if you adjust the aperture. You need the images to be identical to merge them effectively.
Different time, weather, or from a different Angle
If the subject or scene you want to shoot is problematic because the sun is too bright, you can often overcome this by taking the picture at a different time of day, when for example it’s a bit cloudier or the position of the sun in relation to your scene has changed. This option will decrease the contrast and bring the dynamic range of the subject closer to that of the camera. Simply ensuring that you have your back to the sun when taking a photograph can make a difference in whether it is overexposed or not.
Use artificial lighting or a flash
You can use artificial lighting or a flash to add light to the darker parts of the image. This option decreases the difference between the lightest and darkest areas of the image and allows your camera to capture the entire gamut of light in one photograph.
When a flash is used, the light on the subject is closer to the amount of light in the background, and this narrowing of the dynamic range is often enough to capture the image effectively without any need for editing.
A flash is an excellent tool for capturing high contrast scenes, but it takes practice learning how to balance the light from the flash and the natural light. An off-camera flash is even better, but it can add to the amount of time it takes to take the shot as well as to the amount of camera gear you have to carry around.
Photo editing
There are some scenes when it is virtually impossible to deal with dynamic range problems in-camera, and you will need to use photo editing software to adjust the contrast. But the likes of Lightroom and Photoshop have come a long way in the last 10 years in being able to recover the areas which are underexposed or overexposed. So don’t be afraid to try to fix your images in post-production if needs be.
Cameras have limitations in the amount of light they can capture. When a scene’s lighting extends beyond the capabilities of the camera, these tools and techniques can still help you create a dynamic photograph of the scene. As you experiment with each of them, you will learn which is the best solution to use in a particular situation. You will soon be taking a dramatic high contrast image despite the constraints of the dynamic range of the subject or the camera you’re using.
Photo credits: Kav Dadfar – All rights reserved. No usage without permission.
