Beginner's guide to Dynamic Range

Fujifilm’s professional SLR range has long offered extended dynamic range, and now that technology has made its way down to the consumer FinePix range with the introduction of the FinePix F100fd and S100FS. But what exactly is ‘dynamic range’ and what does it mean to the average photographer? Read on to find out...

Fujifilm's professional SLR range has long offered extended dynamic range, and now that technology has made its way down to the consumer FinePix range with the introduction of the FinePix F100fd and S100FS. But what exactly is 'dynamic range' and what does it mean to the average photographer? Read on to find out...

In relation to photography dynamic range refers to the darkest and brightest tones that a camera can record in a single exposure. A typical scene can have highlights that are many thousands of times brighter than its deepest shadows, beyond the capabilities of any digital camera.

There are several ways that dynamic range can be measured or quoted. One is 'contrast ratio'; this simply shows how much brighter the brightest part of the scene is than the darkest. So a scene with a contrast ratio of 1:1000 has highlights 1000x brighter than its darkest shadows. Real world contrast ratios range from as little as 1:8 (on very overcast days) to as much as 1:10,000 on a very bright sunny day, though this would be unusually high.

In the UK contrast ratios are likely to top out at about 1:4000. It has been estimated that the human eye can see around 1:16,000 contrast ratio at one time, though once you take into account the opening and closing of the iris this extends to as much as 1:17000000!

1 The dynamic range of a scene, from the darkest shadow to the brightest highlight can be as much as 12 stops (1:4096), or even more in some circumstances.

2 Most compact digital cameras have a much more limited dynamic range, and any tones outside this, shown here as the red and cyan blocks on the tone gradient, will be 'clipped'; recorded as pure white or pure black. Generally with a correctly exposed shot the highlight clipping will be much more obvious.

2 A camera with a wide dynamic range will capture a wider range of tones in a single shot, with the same exposure. This means less clipping of the brightest highlights and deepest shadows.

For photographers there is a second way of measuring dynamic range that uses more manageable and relevant numbers, which is to use 'f-stops'. Most photographers are familiar with the idea of a 'stop'; increasing exposure by one 'stop' doubles it, decreasing by one 'stop' halves it. Therefore F4 to F5.6 is one stop, as is 1/200th second to 1/400th second.

Using the previous examples this means a scene on a cloudy day has around 3.0 stops of dynamic range, (contrast ratio 1:8), whereas a very bright day may have 12 stops (1:4096), with each stop representing a doubling of brightness as you move from the deepest shadows to the brightest highlights.

Most compact digital cameras have, at their lowest ISO setting, (which is the best), around 6 or 7 stops of dynamic range, meaning it's impossible to capture the full range of brightness's in a single shot on a very bright, contrasty day. This means that shadows below a certain point, and highlights above a certain brightness will be 'clipped', (recorded as pure black or pure white respectively). The wider a camera's dynamic range, the less clipping you'll see in the final shot. Fujifilm's new models offer up to 2 stops more dynamic range than other compact cameras. (2 stops means 4x more dynamic range), which means you're far less likely to see clipping of highlights even on very bright days.

4 To demonstrate how much difference the 2 stop extra dynamic range offered by some FinePix cameras can make, here's a shot taken with the 'standard' dynamic range.

5 All the red areas shown here have clipped to pure white and this is detail lost forever.

6 Here's the same shot taken with the FinePix '400%' dynamic range option enabled; there are no clipped tones at all and the fine tonal detail on the flower's petals is captured perfectly.

Highlight clipping looks much worse than shadow clipping, and can mean pale skies turning white. To avoid highlight clipping try reducing exposure slightly (by -0.3 or -0.6 EV).

7 The most common problem caused by the limited dynamic range of camera sensors; clipped highlights leading to a loss of detail in bright skies.

8 Fujifilm's new FinePix F100fd and S100FS cameras offer up to 400% more dynamic range.