by Sarah Parrish

Created on: August 28, 2011   Last Updated: August 30, 2011

Back-lit subjects in photography make lovely portraits and can create a soft, pleasing, halo-like effect.  For photographs of small objects, back-lit photos also give the subjects a natural frame and can make photographic subjects look bigger.  For setting up back-lit portraits, place a light source behind the subject, aimed upward.  Generally, for objects, if you aren't using a light diffuser or a light box, simply placing the object in front of a bright window can create a natural back-light.  While back-lighting subjects is an excellent photographic technique to maximize attention on the center of the image, correct use of lighting can sometimes pose a difficulty.

One of the most challenging aspects of photographing a back-lit subject is how to control the camera's exposure.  Since most cameras with automatic light metering are designed to set the exposure to a time that won't clip either end of the image histogram, you might often see your subject in a poorly lit segment of the image, while the background is well-exposed.  Unfortunately, the background isn't the part in which you're interested.  There are two common methods of addressing this issue: use a flash or use Adobe Photoshop.

If one is interested in using Adobe Photoshop to solve this problem, the answer is relatively straightforward.  Take two pictures of the subject - one with the background exposed properly, allowing the camera to set its own exposure time.  Take a second picture either zooming in on the subject so the camera sets exposure time for the subject, itself, or manually control the exposure time of the camera and increase it.  After these images are transferred to a computer, a user can open both in Photoshop and extract the subject from one image, fitting it to the exact placement of the subject in the image with the correctly exposed background.

To take a picture that doesn't require post-processing, but has a correctly exposed back-lit subject and background in a single image, set the camera as you would to allow it to auto-rate the exposure and set itself accordingly.  Next, take a stand-alone flash on a stand, and set it up to illuminate the subject as you would if you were taking a picture of the subject zoomed in.  The only flaw with this method is that it can create unwanted shadows.  To reduce those, use multiple light sources.

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