Pixiq

HDR photography has many different applications in the photographic world. Architectural interior photographers can solve the extreme contrast situations and simplify the complex flash arrangements customized to each location. Landscape photographers can shoot new subjects that they would normally pass by. Large panoramas capture an enormous dynamic range of light. HDR photography can expand your potential subjects in all sorts of situations. It can breathe new life into your creative side and allow you to see the world in an entirely different way.

Judging Contrast

What are the ideal conditions for HDR shooting? Any scene with static subjects and a higher contrast range than your D-SLR can capture makes for great HDR shooting, though you don’t necessarily have to limit yourself to these ideals. The first step is to visually analyze the contrast of the scene.

We perceive two kinds of contrast: color and brightness. Color contrast is not an important factor in determining dynamic range, but brightness is. Here’s a quick exercise to determine the range of brightness for any scene: Switch to spot metering in your camera and take a reading of the brightest and the darkest areas of the scene. The difference in exposure stops is the EV range of your scene. Here are some common shooting situations and the EV ranges I recorded. Note whether the EV range makes the scene one with high dynamic range (HDR), medium dynamic range (MDR), or low dynamic range (LDR).

From this chart, we can develop a few basic concepts that apply to almost all outdoor scenes. The contrast of the scene depends on the direction that your camera is pointed. Point toward the sun and you are working with a high contrast backlit scene; point at 90° degrees to the sun and you are in a middle contrast side-lit scene; shoot with your back to the sun and your are in a low contrast front-lit scene. Use the direction of light to help you identify the scene’s contrast, then determine the number of exposures and bracketing required to capture the entire dynamic range of the scene.

Additional Considerations

Shooting into a building from outside can be a high contrast scene. The “cave” effect usually has dark shade regardless of the direction of light.

• Reflective surfaces have to be treated as a light source. A reflection of the sun or any other light sources will dramatically increase the contrast. Small reflections can be ignored, but large reflections need to be considered.

• A dimly lit scene can be low contrast. For example, a dimly lit room is likely low contrast if the source lights are not included in the composition.

• During twilight and dawn, the contrast is relatively low unless you point the camera at the rising or setting sun.

• A brightly lit scene can be low contrast. A picture of clouds in the sky, although very bright, is low contrast as long as the sun is not included.

• Don’t try to expose for the sun’s disc. Allowing the sun and a region around the sun to be blown is acceptable in photography.

HDR for High-Contrast Scenes

If you point your camera toward the sun, any object between you and the sun will be backlit. The camera will read the sky at its brightest and the shade at its darkest. This sets the stage for high contrast, and thus requires additional images to capture the full dynamic range of the scene. For such situations, the common exposure sequence of three images at 2EV spacing is usually not adequate.

You can be sure of two things when shooting into the sun: lens flare and high dynamic range. The Horse Shoe Bend image, at right, is an HDR image created by merging seven images at 1EV spacing, covering an EV range of –3 to +3, which was sufficient to capture a saturated blue sky nearly up to the disc of the sun. When the sun is close to the horizon, the lighter blue color near the horizon is a natural occurrence and should not be confused with a halo that occurs during tone mapping. For the final image, I blended the HDR image file I created in FDRTools with one I created in Photomatix Pro.

HDR for Medium-Contrast Scenes

If I point my camera at 90° degrees from the sun, the landscape will be side-lit. The direction of the light creates more diffused light in the shadows. This is a medium-contrast scene, and can be very successfully captured using three images at 2EV spacing, or five images at 1EV spacing, which equates to the same range.

HDR for Low-Contrast Scenes

A low-contrast scene is typical when skies are overcast. The cloud cover creates a huge soft-box effect that softens shadows and diffuses light. In addition to overcast skies, a front-lit scene is low-contrast. The background sky is the darkest portion of the sky, and the landscape is at its brightest. Thus, the overall contrast is low. D-SLRs are very capable of capturing the dynamic range of these scenes in a single image. However, nothing says you can’t shoot a low-contrast scene for HDR processing; I’ve done it many times. You can take three images at 2EV spacing, or even at 1EV spacing, and both will be successful HDR images.