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Tuesday, July 24, 2012

Deep Focus

Focus On Wildflowers • To Print, Or Not To Print • Auto ISO Isn’t Just For Beginners

Labels: How-ToColumnTech Tips
Auto ISO Isn't Just For Beginners

Q My DSLR has a feature called "Auto ISO." Is there ever a time when it can be useful in my outdoor photography? I've been told that it's just another auto-everything mode that takes away all my options.
B. Bennett
Via the Internet

A I used to think that Auto ISO was a lame feature until I figured out that it really does have some uses. As DSLRs have offered more capable expanded ISOs, Auto-ISO settings are more viable; settings at ISO 1600 now yield entirely acceptable results.

Before expanded ISO capabilities, we had just two variables to control exposure: shutter speed and ƒ-stop. Now we have a third that gives us a lot of range. Setting your shutter speed and optimum ƒ-stop coupled with Auto ISO allows you to maintain your shutter speed as the light changes, for example.

I also use Auto ISO as a way to control exposure during a time-lapse segment. When capturing the many images in a sequence during a vast change in the level of light, such as during a sunrise, the exposure needs to keep up with the increase in light. I could set the camera to capture using the shutter priority mode, but the shutter speeds will vary from long time exposures to fast shutter speeds as the sun comes up. Setting the camera to the desired ƒ-stop and shutter speed along with Auto ISO keeps everything but the ISO constant. Early in the sequence, the ISO would be high, but still very usable in the final rendition, while in the bright light, the ISO can go all the way down to 50. When I'm taking time-lapse from dusk into night, I prefer to maintain long exposures throughout to blur car lights or emerging stars into streaks. By setting the exposure to several seconds with the desired ƒ-stop and allowing a short time between exposures, I can keep it all consistent by using Auto ISO for the changing light.

So think of Auto ISO as another creative tool that gives you more, not fewer, options that will help you solve photographic problems.

For information about upcoming seminars and digital-imaging workshops, visit www.georgelepp.com. If you have any tips or questions, address them to: OUTDOOR PHOTOGRAPHER, Dept. TT, George Lepp, 12121 Wilshire Blvd., Suite 1200, Los Angeles, CA 90025-1176 or online at www.georgelepp.com.


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