This problem has been around for as long as people have used cameras. The tools of photography – film or imaging CCD – simply cannot see the same range of light that our eyes can. This is the problem that a photographer has always faced; the captured image is more like a “Cliff’s Notes” version of the actual scene because the entire range of light has been abbreviated. Detail and color are lost in both the highlights and shadow areas.

When we shoot with film our options are limited if we want to expand the range of light we capture (also called range of tones or dynamic range). With print film we tended to expose for the important shadow detail while on slide film we would favor the important highlights. Then with skillful manipulation in the darkroom the photographer would dodge and burn the image during printing in order to render the full range of details desired.

Digital imaging has opened up a whole new set of possibilities. Chief among them is the ability to merge the best parts of several images together in order to create one improved image. The most obvious example of this type of merging is when we cut out Uncle Paul from one image and paste him into another. However there is a different type of merging that can help us with our dynamic range issue.

Thanks to digital imaging and computer software we can now easily merge multiple images of the same subject, shot at different exposures, into a single image that reveals all of the previously lost shadow and highlight detail and color. We in affect expand the dynamic range of our images – High Dynamic Range (HDR) photography.

There are a few key tools for those who are interested in trying their hand at HDR:

1) First a DSLR or high end compact camera that provides Aperture Priority exposure mode plus the ability to over and under expose an image.
2) A tripod is highly recommended along with a remote release, but it is possible to shoot hand held if the photographer is well braced.
3) Software is required that blends several images into a single HDR image. Photoshop CS has the capability and it is found under File / Automate/ Merge to HDR. However I prefer to use a program called Photomatix Pro. Photomatix is less expensive, offers more control over the process yet its two click simplicity can have anyone up and running quickly.
Tip: Know your camera. Almost every DSLR has an automatic exposure bracketing (AEB) setting. Find it and put it to use to make the HDR process very easy.

Many HDR images can be made from two to three exposures while other scenes may require seven or even nine exposures. The clue is that the greater the difference between shadows and highlights the more exposures it will take to capture the whole range. Start out using three images and expand your horizons after you have mastered the basics.

Here are the basic steps:
1. Set the camera’s ISO 200, or ISO 400. This extends the range available for the exposure bracketing settings.
2. Set exposure mode to Aperture Priority. By locking in the aperture value the photographer is able to maintain the same depth of sharp focus in each exposure.
3. Set the camera to continuous shooting mode.
4. Scene selection: it should be bright and with few moving subjects – movement in the distance is alright but subjects that are prominent or close to the camera should be stationary.
5. Put your camera on the tripod and attach the remote release. If your camera or lens has image stabilization and you opt to hand hold, make sure IS is on.
6. Set the automatic exposure bracketing function or manually set each exposure. Using the camera’s scale select the appropriate bracketing. Choose one and a half stops between each exposure if the sun is behind or to the side of the photographer. Use two and a half stops if the sun is in front of the camera or if there is a very bright highlight area.
7. Trip the shutter with the remote release or if hand holding, press the shutter button gently. Continue to hold the release or shutter button until all three exposures are taken.
Now the fun begins. The captured sets of images are downloaded to the computer and opened in the software. Depending on the photographers software choice it can take only two or three clicks to generate an HDR image from the bracketed set of three. A photographer who is comfortable with color, gamma and noise reduction settings can choose to adjust these and more. Use some care because like any technique HDR can be over done!

HDR methods can save the day when confronted with a high contrast scene. Using HDR techniques can also be a creative boost to any photographer. The resulting images can range from subtle improvement to dramatic interpretation. Given the low cost of entry it’s easy to give it a try!

Notes:

1) Though technically an HDR-like image can be made from one RAW image file it will not be a true HDR image. There will be a significant sacrifice of either shadow or highlight detail.
2) Always shoot for HDR using Aperture Priority mode. Manual exposure can be used but change shutter speeds to achieve exposure bracketing, leave the aperture as set for all captures. Varying the aperture is the #1 reason some HDR images look ghosted or badly focused.
3) The article mentions that HDR can be accomplished with a hand held camera. This is true, but to make sure the images are all perfectly in register the photographer should use a tripod.

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