Sirui Aurora 85 mm f/1.4
11. Autofocus and focus breathing
Autofocus
The autofocus of the Sirui 85 mm f/1.4 operates completely silently and at a reasonable speed. Running through the entire focusing range and confirming focus takes 0.6–0.7 seconds and is performed smoothly, without any hesitation, oscillation, or pauses. This time can be shortened slightly by switching the autofocus mode from AF-S to AF-C.The accuracy of the focusing mechanism was also a pleasant surprise. It may not have been quite as flawless as that of the manufacturers' own lenses, but there was no noticeable discomfort during use, and the lens produced only a negligible number of obvious misses.
As for any tendency to focus in front of or behind the intended subject, we did not notice any such behavior on any of the camera bodies used in the test.
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| A7R IIIa, f/1.4 |
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| A7R V, f/1.4 |
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Focus breathing
Focus breathing tests show reframing images as you oversharpen them. We conduct the test by manually passing from the minimum focusing distance to infinity with the aperture stopped down; then we check how the field of view of the lens changed as a result.A frame change ranging from 0 to 5% we consider to be low. Between 5 and 10% you can speak about medium levels. Usually such values also constitute the maximum efficiency level of any breathing compensation algorithms, present in some bodies. Between 10 and 15% focus breathing is high; above 15%, its level can be called very high.
The test video of the Samyang lens is shown below:
