HDR Capture

Suffering from burnt out windows in your interior architectural shots? Struggling with your sunsets and the skies being far too pale? HDR imaging might just save your day. Mike McNamee takes tea with architectural specialist Paul McMullin and they chew the fat over how they used to do bracketing ring-arounds!

Introduced in Adobe CS, the HDR Merge capability uses several bracketed images of the same scene to compile a new image, in which the wide range of light values are harmonised. Take Paul’s scene opposite as a typical example. The interior of the apartment is reasonably exposed for the back of the furniture but the light from the windows has burned a hole in the floor, the outside scene is almost invisible, the TV is over exposed and the tungsten down lighters have burned the wall paper. To light a set such as this for a transparency, you might typically bring in flash main-lights, add supplementary lights in the corridor, gel the windows, switch the down-lighters for only part of the exposure and, to cap it all, make a 9-shot ring around to ensure at least one transparency was optimum – happy days!

A scene such as this, showing the interior of a room with a sunlit view outside the window will have a dynamic range of approximately 100,000:1. Compare this with the range of the average camera of around 4,000:1 and you can see why your windows are burned out!

The basis of HDR is simple. You accommodate the various exposure requirements by bracketing the same view at different exposure levels and have software fix up the wide dynamic range into something more useable for poor old Photoshop’s 8-bit system. As long as nothing in the scene is on the move (eg fluttering leaves) you are OK provided you bracket your 3 to 9 shots using the same focus, white balance, aperture and zoom position – the camera, by definition, has to be on a sturdy tripod and make sure you don’t move it when changing any exposure settings. Auto-bracketing using the camera utility is better than manual changing, providing the auto has enough bracketing span for your exposures, which are a stop apart. You should change shutter speed to make the exposure shift so that depth of field blurring does not change in the scene.

Paul decided to use HDRSoft’s Photomatix after reading Uwe Steinmueller’s review (at www.outbackphoto.com). Photomatix may be downloaded as a trial version for free and purchased for $99. He used a 7-shot bracket on a Nikon D2x using a 12-24mm Nikkor. The sequence is annotated and the complete shot is the last on the page. Over a cuppa we pondered how long it will be before the camera includes built-in software to do the job – now won’t that be cute?

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