Tech Check Dynamic Range

How many tones can your camera sensor pick up?

What is dynamic range?

It’s the proportion of tones between pure black to pure white that can be recorded by your camera’s sensor in a single exposure.

Can’t all tones in a scene be captured?

In normal lighting, it’s relatively straightforward for a modern camera sensor to capture all the tonal range, but in very bright conditions it’s often not possible to record both extreme ends of the tonal scale in one shot.

What happens if the dynamic range exceeds the camera sensor’s capabilities?

As long as you shoot in the camera’s native raw file format, then in postprocessing you will be able to find some additional data at either end of the dynamic range, and effectively compress highlights or boost shadows to reveal extra detail.

Can you always get that additional information back?

Sometimes the dynamic range is so great that you need to shoot several bracketed shots and combine them to create one high-dynamic-range (HDR) image. One shot records highlight detail, one midtones, and one the shadows; when they’re merged together in software, you have a greatly increased dynamic range to play with.

Is it easy to create HDR images?

As long as you have the frames capturing a large enough tonal range, HDR images can be merged really simply in software like Photoshop and Lightroom.

For this example image I used Lightroom Classic. 1 Select all the bracketed images (often three, but five in this case).

2 Go to Photo > Photo Merge > HDR.

3 Lightroom will open a new dialog box. Make sure Auto Align and Auto Settings are ticked. When the preview image is visible, click the Merge button and the images will then be merged together by Lightroom. 4 When the merged image is completed, it will be visible in the library as a DNG file, with an ‘HDR’ in its file name. 5 You can work further on the finished image as you would any normal raw file, but the dynamic range is increased on the sliders.