Best way to map PDAF errors?
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:
Close target under Tungsten light (small size target, e.g. Focus Pyramid)
Far away daylight target, shorter than infinity (custom target)
Infinity under daylight (urban landscape)
In each distance, test the following focal lengths:
Wide end - 17mm
Middle of the zoom - 30mm
Tele end - 50mm
In each focal length, test four modes:
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
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
Manual focus using magnified LV
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).
|Quick by Fausto Zamparelli|
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from Close up image without a macro lens