A surprising amount of thought and planning goes into HDR photography. Because HDRs use multiple exposures of the subject, any movement at all can destroy the final result. (There’s a class of images that use the HDR tonemapping tools with only a single exposure- I’ll talk about these in a future entry. I call them “false HDRs”, and they can be quite beautiful if done properly.)
Things to consider:
- Crowds of people
- anything that moves
For the most part, a tripod mount is critical, although I’ve created a number of successful HDR images handheld or using nearby surfaces as a brace (particularly when my tripod was out of commission for a while after the mount screw broke).
Minor shifts between exposures can often be corrected. The software I use, photomatix, will correct for small camera shifts between exposures, and also has a “feature matching” selection that will accommodate larger problems. When you have to rely on these tools, it’s important to take a very close look at your image to make sure strange artifacts don’t appear in the final. I did once manage a very presentable sunset HDR from a moving car (I was in the passenger seat, and the highway was straight and smooth).
I tend to prefer three-exposure HDRs for their simplicity. Alignment becomes more critical as you increase the number of exposures.
Of course, this drawback of HDR photography can also be used to your artistic advantage. For instance, for Halloween, I featured an image titled “Ghost” in my ImageKind galleries, which had a person walking through the scene during the three exposures:
In the end, you simply have to plan ahead and sometimes be very patient to get the right series of shots for an HDR. I’d love to be out shooting right now, however it’s a windy day outside.
In the next journal entry, I’ll discuss more environmental factors, including lighting and clouds.
-www Jan 25, 2010