DSLR KAP: Auto focus modes and the moving camera

I have just returned from another disappointing flight which produced far too many blurred shots like the image on the left. The camera doesn’t do this when it’s in my hand so it must be the big movements when the rig swings that causes the problem: this doesn’t look like motion blur caused by slow exposure- I have seen plenty of that, this looks like a focus failure!

I worked through the focus settings and took a burst of shots leaning out of the window and waving the camera as it shot.  I tried to emulate the kind of motion I have seen the rig perform:

The D5100 AF (AutoFocus) settings: there are 2 sets of settings for autofocus

1: the servo mode which can be set in one of 3 ways:

  • AFS= Single servo
  • AFC= Continuous (for tracking a moving target) which apears as ‘AF full time servo’ when in Single point mode ( see below)
  • AFA Auto switched between AFS nad AFC on detection of movement

2: the AF area mode which can be set as either:

  • Single point or
  • Auto Area AF

The key setting is the Single point area mode: waving the camera produced sharp focus when in Single point mode regardless of the servo actuation.

So setting single point AF  works a treat with the moving camera ( see top of this post) But switching the camera to live view removes the option and re-sets the focus mode! The settings offer a different set of options when the camera is switched to live veiw: single point is no longer available and the options change to:

  • Face priority AF
  • Wide area AF
  • Normal Area AF
  • Subject tracking AF

I selected Normal Area Mode in the hope it might be similar to single point…so far it seems to work.

KAP demands on AF are different to those envisaged by the camera designer: the AF is designed to work with a moving subject or moving camera …but not both!

About billboyheritagesurvey

Heritage worker
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