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Nifty fifty STM - focus issues, or human error?

Started Nov 16, 2017 | Discussions thread
OP TMHKR Forum Member • Posts: 83
Re: Nifty fifty STM - focus issues, or human error?

Tests completed.

As you can see, PDAF is inconsistent on bigger apertures (it's good with smaller ones), while CDAF nails the focus in all situations. I guess I will just have to live with it. Just to note again, this is not front or back focus problem, since it jumps back and forth at random.

Also, a note regarding photos of my brother from the first post. On these, I used the "focus with center point and recompose" method. Perhaps that's the reason for blurry photos, since the aperture was wide-open?

Global parameters:

- took 2 photos in each test
- ruler target at 45 degrees
- aperture priority mode
- 2 sec delay timer
- center AF point
- tripod

Test 1 / 50mm 1.8 STM / F1.8:

- PDAF: inconsistent
- CDAF: all good

Test 2 / 50mm 1.8 STM / F5.6:

- PDAF: all good
- CDAF: all good

Test 3 / 18-55mm 3.5-5.6 IS STM / 18mm / F3.5:

- PDAF: inconsistent
- CDAF: all good

Test 4 / 18-55mm 3.5-5.6 IS STM / 55mm / F5.6:

- PDAF: all good
- CDAF: all good

PDAF: center AF point, viewfinder
CDAF: AF area centered, live view, electronic first curtain
AF sensor: 9-point all cross-type, center point double cross-type at F2.8
Live view: Canon Hybrid CMOS AF (first generation)

50mm 1.8 STM, F1.8, PDAF, photo A, focus centered on target

50mm 1.8 STM, F1.8, PDAF, photo B, focus centered on target

50mm 1.8 STM, F1.8, CDAF, photo A, focus centered on target

50mm 1.8 STM, F1.8, CDAF, photo B, focus centered on target

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