Tuesday, November 10, 2009

Swing into focus (Basic)



Getting sharply focused images is a challenge for toddler photos. I want to capture shots of our toddler in all his joy and it is at those times when his movements are least predictable.  I tried out a few techniques to help improve focus.

Method 1: focus priority + hold down the shutter
I normally use the focus and recompose technique (select the focus point closest to the point of interest, half-press the shutter to acquire focus, recompose, then press the shutter all the way).  The problem with the focus and recompose technique is that there is an interval between the acquisition of focus and the release of the shutter.  When our toddler moves, as he frequently does, the focus is lost. 


Steps:
1. Switch to AF-S / activate focus priority. Some cameras like the D200 have a setting called "focus priority" (don't release the shutter unless and until the image is in focus). My D80 doesn't have such a custom setting but behaves as if it's on focus priority when I switch to AF-S (autofocus single).
2. Intentionally focus somewhere else first.  It seems the D80 has a threshold of acceptable focus that is not high enough for me.  In other words, sometimes it will consider the image in focus when I don't consider the image to be sufficiently focused. To avoid getting a shot that's not sufficiently focused, I intentionally put the image out of focus first by focusing somewhere else.
3. Put the focus point on the target and hold down the shutter. With the focus point over the now-blurred target, I hold down the shutter.  The shutter doesn't release immediately because it's on focus priority. However, as soon as the image is in focus, the shutter releases.

Method 2: AF-ON
The logic for this one is similar to the previous method but somehow, it seems I get better results with this method. I first customize the AF-L/AE-L button to AF-ON.  This means that pressing the AF-L/AE-L button will acquire focus. Pressing the shutter half-way no longer causes the camera to focus.

Steps:
1. Switch to AF-S / activate focus priority.
2. Intentionally focus somewhere else first.
3. Put the focus point on the target and hold down the shutter.
4. While holding down the shutter, hold down the AF-L/AE-L button. As soon as the image is in focus, the shutter releases.

Method 3: trap focus (aka focus trap)
Our toddler was playing with a swing and I used trap focus (which I read about at other sites) with some success to get shots of him on the swing. This one also requires customizing the AF-L/AE-L button to AF-ON.


Steps:
1. Switch to AF-S / activate focus priority.
2. Put the subject at the target distance and focus. In my case, I grabbed the swing with my free hand, held it in the position I wanted for the shot, then focused using the AF-L/AF-E button.
3. Allow the subject to move.  The subject comes out of focus.
4. Keep aiming the focus point at the same target you chose in #2. In my case, the eyes.
5. Hold down the shutter.  The shutter doesn't release immediately because it's on focus priority.
6. Wait for the subject to come into focus.  As soon as the subject moves into the distance where it comes into focus, the shutter releases.