How To Bracket More Than 3 Photos

I figured I'd make a post on this because I see the topic come up a lot on forums and there's a lot of misunderstanding out there.  The basic problem is this:  A lot of cameras support exposure bracketing, but they are limited to 3 photos in the bracketed set.  HDR composites often work best with 5-, 7-, or even 9-shot brackets, so what to do?

Let's say you want a 5-shot bracket, spaced at 1EV increments.  Here's the easy way:
  • Put your camera in aperture-priority mode if you're doing HDR (you want the exposure adjustments to be made by varying the shutter speed not the aperture; "A" mode will lock down the aperture).
  • Turn off Auto ISO.  Set ISO to your desired value and turn off any setting that allows the camera to override it.
  • Set up your camera to do it's normal 3-shot 1EV bracket
  • Now the trick (and it's wow-I-could-have-had-a-V8 obvious):  Dial in -1EV exposure compensation.  In aperture-priority mode and with ISO locked down, this will shoot each photo with one stop faster shutter speed than it would at 0EV.
  • Shoot your 3-shot bracket.  This will result in 3 photos:  -2EV, -1EV, and 0EV
  • Dial in +1EV exposure compensation.
  • Shoot another 3-shot bracket.  This will result in 3 photos:  +2EV, +1EV, and 0EV
  • Now you have a 6-shot bracket with an extra 0EV photo.  Select the sharpest 0EV photo and throw the other one away.
You can do the same trick for a 9-shot bracket by shooting three 3-shot brackets with exposure compensation values of -3EV, 0EV, and +3EV for each bracket.  This will result in 9 photos from -4EV to +4EV.  You can turn that into a 7-shot bracket by simply deleting the -4EV and +4EV photos from the set.  Although if you're doing this for HDR you just as well use the +/-4EV photos too.

The bigger point is this:  There's nothing special about the bracketing feature of DSLRs other than automation.  You can do it all manually by adjusting either exposure compensation (in A mode) or shutter speed (in manual mode) for each shot.  That's old school, the way your Daddy (or maybe your Grandaddy) did bracketing.  Although he also undoubtedly walked 5 miles through a blizzard without a coat while doing this, because back then, men were men.  Another implication is that a camera without built-in bracketing can do HDR just fine.  The limitation there is that the process takes a little longer and therefore has more opportunity for movement of objects (clouds, people, branches blowing in the breeze, etc.) between shots.  But if you're shooting HDR, you're probably already choosing fairly static imagery so in most situations it's totally manageable.

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