High Dynamic Range

HDR - Take a number of images and put them together to get the best from each photograph - merge them to see details in the light and dark areas.

What is dynamic range?
In simple language it is the range of brightness values. For example, if you look out of your window the sky tends to be brighter than the ground but our eyes and brain make it so that we can see both. Our eyes are extremely good in dealing with large variances in brightness values.

If you go from a dark to a light room our eyes take a moment to adjust. When it comes to looking at brightly-lit scenes our eyes can take in the darker areas by adjusting very quickly. So, to our eyes sky and ground tend to look very similar in brightness but to a camera they do not.

Dynamic range means capturing bright and dark areas, both with good detail and well lit.

For an HDR scene we need to take different shots of the same scene with different exposure values.

Important to note that when you are shooting HDR scenes the camera must be very still, using a tripod is vital any movement is bad - be aware of clouds or tree leaves moving in the wind otherwise you will end up with double exposure. If you have a remote shutter release this is a good time to use it. Discard any images where the camera moved.

When changing the exposure setting of each shot, it is best to change the shutter speed not the aperture, (f/stop). One reason is that you will want the depth of field to match each image.

From Photoshop CS2, HDR software has been incorporated in the package. It is possible to obtain good free HDR software in the web.

Pictures taken by John Arnold for a HDR tutorial.