This is a guest post from fellow photographer Bob Lussier
I absolutely love the auto focus system in my D700. It is tack sharp, has 51 points of focus and can auto track a moving object by simply changing a setting. With my eyesight, I rely heavily on it. Except when shooting HDR.
Even the most sophisticated auto-focus system can fail you under certain circumstances. Ever try to focus on a fog bank or bright blue sky? Or in low light? If there is nothing to lock on to, auto-focus becomes uncooperative, continuously “hunting” for an anchor point.
If you add to the equation 3, 5, maybe 9 brackets for HDR, you are asking for trouble. If Auto-focus has to “hunt” in the middle of a bracket sequence, you run the risk of getting some fuzzy brackets. And nobody likes fuzzy brackets.
A lot of my HDR shooting is in dark corners of old buildings, The perfect situation for auto-focus “hunting”. I also often shoot wide open, selectively focussing on the subject. I rely on manual focus to ensure that my focus is exactly where I want it and that it stays there throughout the bracket sequence.
“But its really dark! I can’t see!” … No problem. Carry a small flashlight in your bag. Use it to light your subject as you focus.
Thanks for reading and happy shooting