Best way to map PDAF errors?

Started Jun 24, 2012 | Discussions thread
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Prognathous
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Best way to map PDAF errors?
Jun 24, 2012

I'd like to test my most used lens (Tamron 17-50/2.8) for PDAF errors with my A77. Here's the test protocol that I plan to use:

Test targets at three distances:

  1. Close target under Tungsten light (small size target, e.g. Focus Pyramid)

  2. Far away daylight target, shorter than infinity (custom target)

  3. Infinity under daylight (urban landscape)

In each distance, test the following focal lengths:

  1. Wide end - 17mm

  2. Middle of the zoom - 30mm

  3. Tele end - 50mm

In each focal length, test four modes:

  1. Phase detect, no micro-adjust calibration, AF drive speed set to Fast. Then turn on micro-adjust calibration, and repeat test attempting to calibrate this point

  2. Phase detect, no micro-adjust calibration, AF drive speed set to Slow. Then turn on micro-adjust calibration, and repeat test attempting to calibrate this point

  3. Manual focus using magnified LV

  4. Manual focus using regular view and focus peaking

In each distance/focal-length/mode, shoot 3 pictures - the first 2 with focus starting at infinity, the last one with initial focus point reused from the last attempt (just another half-press of the shutter release). In all cases use the center point.

I know it sounds a bit like an overkill, but I believe that this will give me a good picture about what the best compromise micro-adjust settings, and cases where MF is a must (as well as the best MF mode to use).

Other thoughts?

Prog.

Sony SLT-A77
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