High-Dynamic-Range Photography

What is High-dynamic-range (HDR) photography? HDR is a photography technique where you use Exposure Bracketing (EB) and then combine the photos using special software to obtain a single photo. Why would you do this? Think about photos where you had extreme lighting conditions: a photo with bright sunlight and dark shadows. Most cameras can’t capture all the detail in both the bright and dark areas as the sensor technology just can’t see detail in light and dark areas as can the human eye. That doesn’t mean you shouldn’t be able to take the photograph.

How do you achieve an HDR photograph? First you need to obtain three exposures, 2 f-stops apart. Many of today’s cameras offer an Auto Exposure Bracketing (AEB) feature that will allow you to easily accomplish the HDR technique. If your camera doesn’t have the AEB feature, you can accomplish EB manually.

The example below was taken at night which presents a high contrast situation, i.e. bright lights and dark shadows. How do you achieve the range of F stops needed: normal, plus 2 F stops, and neg 2 F stops? In the normal photo below, my camera determined for an ISO 200 and f/4.5 (these settings remained constant for the three photos) the correct shutter speed to be 2.5 seconds.

My preference is to shoot my photos using Aperture Mode. Why? Aperture mode gives control over depth-of-field.

If your camera doesn’t have AEB, you need to do some simple mathematics and take the normal first photo in aperture mode and the others in manual mode You will need to take note of the shutter speed the camera determined for the normal photo. You will need to take the next two photographs using manual mode, keeping the ISO and aperture the same as in the normal photo and adjusting only the shutter speed.

(Note: For one f-stop increase you need to double the speed and for a one f-stop decrease you need to divide the speed in half.)

To increase exposure by 2 f-stops, you would need to double the normal speed twice to give a longer exposure. For the example photos below: the 2.5 seconds times 4 gives a speed of 10 seconds (2.5 x 2 x2=10) and to decrease the exposure by 2 f-stops you would been to divide the speed in half twice (2.5/2/2=0.63).

In low light situations, it’s important to use a tripod as the exposures can be long. It’s imperative when using a tripod to use a cable release or remote triggering of the camera. If you don’t have a remote triggering device, you can to use your camera’s time delay feature.

Remember, any contact with the camera will cause the images to be blurred. In the example above the exposure times ranges from 0.6 to 10 seconds.
Using the three photos above, I combined them using Photoshop’s HDR Merge (see below):

After applying automatic exposure correction in Lightroom, the photo looked overexposed to the lighting that I saw the night the photos were taken.

I then adjusted the exposure to +0.50 from the autocorrect value of +1.40 and increased the Clarity to 26 and Vibrance to 8. Clarity adds contrast to the mid-tones and makes your image look sharper, even though it doesn’t actually add sharpening. Vibrance is a smart tool that increases the intensity of the muted colors and leaves the well-saturated colors alone.