AGeoJO
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 People and Portrait Image Thread using Sony | |
numbertwo wrote:
I've been doing some more eye-af tests.
The adapted sigma 35 1.4 is the most accurate lens I have hitting on the eyeball in every situation. It's also a really sharp lens even at close distances. When I compared it agains the Samyang 35, the Samyang was a bit sharper for landscape, but the sigma was better at portrait/close distances.
Samyang 85 1.4 and Sony 50 1.8 focus more in the eye lashes when very close, and going a bit further, it's more on the nose or eyebrows most of the time. These two lenses are also not as sharp at close distances compared to further away.
- The accuracy is better shooting with the camera in landscape orientation than in portrait orientation.
- Disabling IBIS improve accuracy for af-c eye-af, tested the Samyang and it makes a difference.
- In af-s, all lenses are pretty much perfect in the eyeball.
- I've tried back button af, disabling and enabling face detection, but not significative differences.
So,
- maybe IBIS movements are messing up af, specially focusing out center?
- maybe af-c behaviour is "too predictive" trying to focus forward?
Edit: I've been taking more test shots outdoors:
- The Sony 50 constantly front focused by a bit, only tried af-c eye af ibis on and off (camera in vertical orientation), but also the lens is not very sharp at 1.8...
- The sigma 35 seems to be front focusing as well most of the time in portrait orientation off-center.
Most of the tests were with the Samyang 85:
- AF-C, Eye-af ON, IBIS ON, portrait orientation off center: 60% very OOF (nose), 40% in focus
- AF-C, Eye-af ON, IBIS OFF, portrait orientation off center: 30% OOF, 70% in focus, the OOF are not as bad as with IBIS ON.
- AF-C, Eye-af OFF, small flexible spot, IBIS ON: 30% slightly OOF, 70% in focus.
- AF-C, Eye-af OFF, small flexible spot, IBIS OFF: 20% slightly OOF, 80% in focus, the sharpest of the bunch have been taken in this set.
Conclusions:
- Seems that IBIS is indeed negatively affecting focusing accuracy.
- Eye-af seems to be worse than small flexible spot.
Thanks for doing the test. So, the AF performance of the Samyang 85mm is kind of sketchy, it seems. That could be the result of reverse engineering, I guess then.
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On the last leg of my trip to Peru but this image of a local girl and her baby lama in Ollantaytambo from a few days ago...
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