Dynamic range can make or break a photo. We explain how to check if you're capturing all the tones in a scene and ways you can boost your dynamic range.
If you've ever taken a shot in sunlight, or any other situation where the brightness range is high, the chances are your camera will have lost some detail in the darkest parts of the picture, the brightest parts or both.
It's one of the most common photography problems you'll encounter, but it isn't to do with exposure. It's because the difference between the brightest and darkest areas, or 'dynamic range', is so great that you can't find a single exposure that can capture them both.
Digital camera sensors can capture a wide range of brightness values, but there is a limit. If you're faced with a scene that has a wider dynamic range (or brightness range) than the camera's, you may well have a problem.
In this tutorial we'll offer some of our best camera tips and expert advice for recognising, measuring and overcoming this problem. First, we'll answer some of the most common questions photographers have about using dynamic range in photography.
Common questions about dynamic range in photography
What is dynamic range in photography?
Dynamic range is a way of describing the range of light intensities from the darkest shadows to the brightest highlights. It can be measured in Exposure Value (EV for short) or 'stops'.
Some scenes have a wide dynamic range, meaning that there is a significant difference in exposure value between the shadows and the highlights - such as shooting a silhouette at sunset - while others have a much narrower range of brightness levels.
When you take a picture, there are actually two dynamic ranges to consider: the dynamic range of the scene you're photographing and the dynamic range of the camera's imaging sensor.
Aren't they the same?
The sensor inside your digital camera can only record a fixed dynamic range in a single exposure. As long as the difference in brightness between the darkest and lightest areas of a scene fall within this dynamic range, you'll be able to record detail in both areas simultaneously.
For example, if a camera sensor has a dynamic range of 8 EV and the difference between the shadows and highlights is 6 EV, then you'll be able to capture detail in all areas of the scene.
However, if the dynamic range of the scene or subject exceeds that of the camera sensor, you'll end up with a picture where the shadows are completely black or where the highlights have 'blown' and become totally white - and sometimes both.
Do all camera sensors have the same dynamic range?
No, cameras vary in their ability to handle dynamic range. The greater the dynamic range of the camera, the more info it'll be able to capture. For instance, the Nikon D610's dynamic range has been measured at between 13 and 14.4 EV at ISO 100.
How do I know if the camera can handle a scene's dynamic range?
In the days of film photography, this was a fiddly process. You'd have to take exposure measurements from the darkest and the brightest parts of the scene, calculate the exposure value difference between the two, then check if the film stock you were using was capable of capturing this range of light intensities and how to set the exposure to do just that.
With a digital camera, you can simply review the brightness histogram on the rear screen. This allows you to instantly see whether the dynamic range of the scene (represented by the histogram) fits within the dynamic range of the sensor (represented by the width of the graph).
If the histogram is 'clipped' at the edge of the scale, you may lose picture detail - either in the shadows (if it's clipped on the left) or in the highlights (if it's clipped on the right). You may need to adjust the exposure to squeeze the scene's dynamic range into that of the sensor.
And quite often, you can adjust the exposure, re-shoot and solve the problem. But scenes with a very wide brightness range also produce a very wide histogram - and sometimes the histogram is so wide that it's clipped at one end or the other, no matter how you adjust the exposure.
The range of tones on an overcast day is quite narrow, producing a narrow histogram. This won't pose any exposure problems. But the extreme brightness range of a sunny day may produce a histogram so wide that it won't fit within the camera's dynamic range no matter what you do.
What's the answer?
The histogram shows you the range of tones in the whole picture, but not necessarily the ones which you're most interested in! Sometimes it's okay to have dense areas of black. It's fine, for example, in black and white photography.
So by all means use the histogram as a guide, but consider checking key areas of the picture yourself. You can do this using your camera's spot metering mode to check the brightest and darkest key areas in the picture to see if there's a single exposure which can capture them both.
Alternatively, you can shoot raw files. These capture up to 1EV of extra shadow and highlight detail that you can extract later in your raw conversion software. You won't see any sign of this on the camera histogram, though, because your camera will display a processed JPEG preview of your image for display on the LCD, even if you've shot in the raw format.
You still have to get the exposure exactly right, even if you shoot raw, but the slight extra leeway might be all you need to capture extremely dark and bright tones in the image.
Sometimes, though, even shooting raw files won't be enough, and this is where you enter the world of HDR photography.
Can I use exposure compensation to improve a photo's dynamic range?
No: your camera's exposure compensation feature only affects the overall brightness of an image. It enables you to shift the histogram left or right along the scale to ensure that either the highlights or the shadows aren't clipped, but you won't be able to increase or decrease the dynamic range itself.
If the dynamic range of a scene is too wide to capture in a single exposure - with both the shadows and the highlights being clipped - you'll need to decide where it's better to capture detail, and adjust the exposure accordingly.
It's usually preferable to 'expose for the highlights' - in other words to reduce the exposure to ensure the brightest areas aren't clipped. However, there are some camera settings that can help you improve the dynamic range.
Which camera settings are those?
You'll get the best dynamic range performance from the sensor if you shoot at the lowest ISO setting using your camera's raw file format. Raw files hold more information than JPEGs and they offer more exposure latitude, making it easier to pull back detail in pictures that are either too bright or too dark.
Most cameras offer an automatic dynamic range enhancing mode, such as Nikon's Active D-Lighting or Canon's Auto Lighting Optimizer. These brighten up shadow areas for a boost in the recorded dynamic range, although they only work with JPEGs.
Finally, as the name suggests, High Dynamic Range (HDR) photography enables you to substantially increase the effective dynamic range. Rather than trying to squeeze the dynamic range of the scene into one exposure, HDR requires several identical images to be recorded at different exposure value levels.
These images are then combined in special HDR software, such as Photomatix, to give a much wider dynamic range than is possible using a single exposure. Some cameras have an HDR mode that can carry out this process automatically for you.
HDR is an easy effect to overdo. If it's not your cup of tea, you'll have to use an alternative technique to reduce the dynamic range when faced with a high-contrast scene.
What techniques are those?
Flash and reflectors can brighten up shadows where detail would otherwise be lost. Landscape photographers use neutral-density graduated filters to do the reverse, ensuring detail is not lost in bright areas.
ND grad filters are clear at the bottom and dark at the top; by positioning the dark half over a bright sky, you can bring its exposure value closer to that of the darker foreground.
These days, landscape photographers are just as likely to take two photos of a scene - one that's exposed to retain detail in the sky and another which has been exposed to retain foreground detail - then combine the two photos in Photoshop or similar software.