Did some non-scientific tests:
DA L 18-55 @ 55mm f5.6:
In focus: 14
Uncertain/ very close: 4
Missed focus: 2
Focus hunts: 1
DA L 18-55 @ 50mm f5.6:
In focus: 16
Uncertain/ very close: 1
Missed focus: 3
Focus hunts: 1
Sigma 17-50 @ 50mm f5.6:
In focus: 7
Uncertain/ very close: 0
Missed focus: 12
Focus hunt: 1, possibly 2
I apparently overlooked one shot in this test.
Sigma 17-50 @ 50mm f2.8:
In focus: 9
Uncertain/ very close: 0
Missed focus: 11
Focus hunts: 3, possibly 4
Sigma 17-50 @ 50mm f2.8:
In focus: 7
Uncertain/ very close: 5
Missed focus: 8
Focus hunt: 0
Lighting condition and testing method used:
Low light - close to but possibly brighter than a bar type of lighting.
I aimed at 20 random things located around in my room. Some tricky some easier subjects. I took the pictures from the same spot - my chair my the desk. I imported the first batch into my PC, and then used these pics as reference for the other shots - to make sure I aimed the proper places.
There's lots of margin for errors, but the results should be more random then. As I've been suspecting all along, the Sigma performed worse. This isn't a conclusion, but still worth chewing on.
Edit: Perhaps I should also mention that I had my Metz 58 AF-2 flash on, and it assisted for focusing.
Last edited by Zafar Iqbal; 12-07-2011 at 12:01 PM.
Reason: typo