Sirui Aurora 35 mm f/1.4
11. Autofocus and focus breathing
Autofocus
The autofocus of the Sirui 1.4/35 is completely noiseless, smooth, and flash quick. Running through the whole distance range and confirming the focus takes only about 0.3 of a second, an excellent result, worth any good journalistic lens. Everything looks and performs as it should in a top-of-the-range, premium instrument, and, I admit, it is a very nice surprise. Inexperienced manufacturers often have many slip-ups in this area.When it comes to accuracy, the situation wasn't perhaps as perfect as in case of the most expensive brand-name lenses, but still there are no reasons to worry. The majority of photos we took in our studio and outside were properly sharp.
When it comes to front or back focus tendencies, we didn't notice any traces of them regardless of what body we used.
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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.
Below we present the test video of the Sirui lens:
If you average out both these results, the lens lands on the borderline between average and high level. The situation is not tragic, but it could have been better.
