Viltrox AF 56 mm f/1.7 Air
10. Autofocus and focus breathing
Autofocus
The autofocus of the Viltrox AF 56 mm f/1.7 Air was tested with the help of the Fujifilm X-T2 and X-T3. In both cases the mechanism was noiseless and moderately quick. Running through the whole distance range and confirming the focus takes typically 0.6-0.8 of a second and it might slow down even a tad further by slight, fast oscillation near the proper position of the focus.When it comes to the accuracy of the mechanism we noticed some differences between both bodies, used in our test. The older X-T2 cooperates with the Viltrox much worse - such a set generated a lot of mistakes and even complete misses. There were moments when the autofocus settings were clearly wrong; only when I pressed the shutter for the third or even fourth time the focus was set properly.
After attaching the newer body, the X-T30, the working culture of the autofocus improved noticeably, with less mistakes and evident misses; still the performance remained weaker than the performance of brand-name Fujinon lenses.
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The situation was a tad better with the lens attached to the X-E5 camera. There were some misses but few and far between; instead we often noticed the slight oscillation, mentioned above, near the focus point.
The photo below shows clearly that the tested Viltrox didn't have any front or back focus tendencies.
| Fujifilm X-T2, f/1.7 |
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Focus breathing
Focus breathing tests show reframing images as you oversharp 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 constitute also 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 Viltrox lens:
