How to Understand Dynamic Range in Photography

How to Understand Dynamic Range in Photography

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The word photograph comes from the greek words phos and graphe, which mean light and drawing, respectively. Thus to create a photograph, in the strictest definition, literally, means to paint with light. But painting with light can be quite difficult given the amount of light you have to work with!

Sometimes you might find yourself in a situation with plenty of light, such as outdoors or in a well-lit gymnasium, and other times things will be so dim that you need to create your own light with a flash or leave your shutter open for a very long time. However, it’s also quite likely you could end up taking pictures when there is a lot of light as well as a lot of shadows, then it can get tricky to nail the shot you want. Fortunately, there’s a term that can greatly assist you in these situations – it’s dynamic range. Knowing what it means and how it can affect your photography will go a long way towards helping you get the photos you are trying to create.

Understanding Dynamic Range in Photography

Setting the Scene

Dynamic range has two main applications when it comes to photography. The first relates to the scene which you are photographing, and the second is more technical in nature and helps describe the attributes of your camera’s image sensor. (This is the little rectangular microchip a digital camera uses to capture an image, much like a little square piece of digital film.)

Most of the time a photographer will attempt to create a picture with a good overall exposure, meaning the bright parts aren’t too bright and the dark parts aren’t too dim. In this sense, Dynamic range refers to the total amount of light being captured in a given scene. If you are taking a picture with a lot of bright parts full of light in addition to a lot of dark parts shrouded in shadow, the scene could be described as having a great deal of dynamic range (high contrast). If, however, the scene is lit in such a way that it is neither too bright nor too dark it could be said to have a low dynamic range (low contrast).

Understanding Dynamic Range in Photography

This picture of a goose has low dynamic range, meaning it’s evenly exposed with no parts being exceptionally light or dark.

Neither is right or wrong

Neither type of scene is necessarily good or bad, but it’s important to know when you go out to take pictures what the lighting conditions are like so you can plan accordingly. If you are shooting in broad daylight you will likely end up with images that are very bright with lots of shadows because the sunlight is strong and overhead. This is known as a high dynamic range scene because it contains elements that are very bright and very dark. You need to know how to control the scene, as well as your camera when this happens in order to get the shot you want.

Understanding Dynamic Range in Photography

This picture of a goose was taken in conditions that resulted in very high dynamic range. Parts of the image are very bright, and other parts are covered in shadow.

Capturing Your Vision

Dynamic range is important to consider when taking pictures. An understanding of the situation in which you’re shooting is essential to capture the shots you want. If you’re painting with light, you need to understand how that light is going to affect your final images.

As an example, here is a portrait I shot outside on a sunny afternoon. My subject was well lit but the background behind her was extraordinarily bright. This resulted in an image that I wasn’t happy with. The viewer’s attention should be on her face but the bright background is competing for attention.

Understanding Dynamic Range in Photography

The histogram will give you clues about the dynamic range

A peek at the histogram for this image reveals what I already knew to be true just by looking at the scene. Much of the image data is gathered at the right and left sides of the graph. This indicates that the scene contains both very bright and very dark portions and thus would be considered to be rather high in terms of dynamic range.

Understanding Dynamic Range in Photography

Pictures like this aren’t necessarily bad. Some photographers actually prefer scenes with really high dynamic range because they create a sense of contrast and punchiness that is often lacking in other conditions with a more even exposure. Personally I’m not a huge fan of these types of images, and in this case, it was easily fixed just by turning a bit to one direction and using the side of a building to create a more even exposure.

Understanding Dynamic Range in Photography

Once again I can look at the histogram in Lightroom and see that now the image data is not separated at two extremes but gathered more evenly in one portion. Alternatively, you could use Live View on your camera and see the histogram in realtime as you photograph. If you see that it looks like two mountains on either side with a valley in between that’s an indication that the scene is going to come out with a lot more contrast than you may otherwise prefer.

Understanding Dynamic Range in Photography

HDR – High Dynamic Range

One trick that more photographers have been using lately is called HDR, or High Dynamic Range processing. This is a way of getting the best of both worlds by allowing you to combine multiple exposures into a single image, using only the parts from each that you need. Thus, in a scene where there are extremely light parts as well as very dark parts you can take a few separate pictures that are both under and overexposed, combine them using software on your phone or computer, and end up with an image that appears to be evenly exposed. One downside to this is that the final image can appear somewhat fake and artificial to our human eyes (if the HDR technique isn’t done well).

Technology to the Rescue

The human eye is a biological marvel. As good as modern digital cameras are they can’t even come close to matching the performance of our own ocular instruments. Digital camera sensors today are leaps and bounds ahead of their forebears from 10 or even five years ago, but our own eyes still trounce them handily when it comes to dynamic range.

The ultimate high dynamic range and the problem it presents

As an example, try standing in a room on a bright sunny day with most of the shades drawn. That creates a high dynamic range scene because there are parts that are very bright (outside the window) and other parts that are very dark (inside). Your eyes will still be able to see colors and shapes inside the room as well as everything out the window. But try to take a picture and things go downhill quickly. You will either get an image that is exposed for the highlights (i.e. outdoors) with the room being virtually black, or the image will be exposed for the room (i.e. shadows) and nothing out the window will be visible at all.

Understanding Dynamic Range in Photography

Camera exposed for the highlights, leaving the room completely dark.

Most cameras take an either/or approach to scenes like this. However, HDR techniques can be utilized to capture three or more images at different exposures which can then be combined to form a more evenly exposed final picture.

Understanding Dynamic Range in Photography

Camera exposed for the shadows, leaving everything outside far too bright.

Technology improves

Even though our eyes still outperform any camera, in recent years digital camera sensors have gotten much better at capturing not just the brightest or darkest portions of a scene, but the brightest and the darkest portions. In this sense, the term Dynamic Range refers not to the lighting conditions but to the capability of the image sensor inside your camera.

Some models like the high-end Nikon D810 or Canon 5D Mark IV are so advanced that a single RAW image fro these cameras can be processed so as to reveal data that might otherwise be lost. For instance, when I shot the sunrise below I exposed for the highlights so I could get a nice clean picture of the rich colors in the sky, but the side effect of this was that the ground went entirely black.

Understanding Dynamic Range in Photography

Thanks to the technology baked into the sensor of my Nikon 750, the camera captured far more data than what you can see initially. I shot in RAW at ISO 100 which meant that I could take advantage of the bucketloads of data that were embedded in this picture and I was able to recover a huge amount of information from those shadows.

Understanding Dynamic Range in Photography

The same image, but with the shadow levels boosted significantly in Lightroom.

This is an extreme example and I wouldn’t normally recommend applying this much post-processing to a picture. But I’m using it as an example to illustrate how much dynamic range a modern camera sensor actually has. Another example, perhaps a more realistic one, showing the importance of having a camera sensor capable of capturing a high degree of dynamic range can be seen in the following images.

The first image is straight out of my camera (Nikon D7100). While the background elements are fairly well exposed, the squirrel and tree are much too dark. Since the scene itself had such a high degree of dynamic range it made getting a proper exposure tricky. Thankfully I was able to use Lightroom to pull up a lot of data in the shadows that would otherwise be lost if the sensor had a lower degree of dynamic range.

Understanding Dynamic Range in Photography

Unedited, with a well-exposed sky and underexposed subject.

A couple of clicks on my computer resulted in the final image which is vastly improved over the original.

Understanding Dynamic Range in Photography

Conclusion

For many years camera manufacturers were engaged in a battle to see who could produce a device with more megapixels. But in recent times, this digital arms race has tapered off since the standard 20-24 megapixels that most cameras shoot at is supremely adequate for almost any situation. Instead, the focus has now shifted towards things like better ISO performance and higher dynamic range on image sensors. It won’t be long until sensors are so good that you will be able to shoot pictures in just about any condition and still get usable images.

Indeed we are living in such incredible times that our cameras can create amazing light paintings, so to speak, in almost any light imaginable. But what about you? Does this article answer your questions about dynamic range or is your head still spinning with terms and technologies? Do you have any questions that weren’t addressed? Please leave your thoughts and questions in the comments below.

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Simon Ringsmuth is an educational technology specialist at Oklahoma State University and enjoys sharing his enthusiasm for photography on his website and podcast at Weekly Fifty. He and his brother host a monthly podcast called Camera Dads where they discuss photography and fatherhood, and Simon also posts regularly to Instagram where you can follow him as @sringsmuth.