Sigma A 35 mm f/1.4 DG II
10. Autofocus and focus breathing
Autofocus
The autofocus of the tested Sigma is based on a double HLA motor (High-response Linear Actuator) that powers a big and heavy focal group. The mechanism is practically noiseless and very quick. In the AF-S mode running through the whole distance range and confirming the focus takes on average about 0.3-0.4 of a second but momentarily you could notice some tiny waverings. The number of these waverings was reduced to practically zero when we passed to the AF-C mode. The mechanism additionally sped up so the focusing time didn't exceed 0.3 of a second. It is a very good performance.The accuracy of the autofocus can be described in similar terms – it was simply splendid. We didn't notice any problems during our test, no matter whether we took photos in the studio or outside. It also didn't matter to which of two cameras, used by us, the tested lens was attached to.
When it comes to front or back focus tendencies, we didn't notice any traces of them regardless of what body we used.
Please Support UsIf you enjoy our reviews and articles, and you want us to continue our work please, support our website by donating through PayPal. The funds are going to be used for paying our editorial team, renting servers, and equipping our testing studio; only that way we will be able to continue providing you interesting content for free. |
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| A7R IIIa, f/1.4 |
 |
| A7R V, f/1.4 |
 |
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 Sigma lens:
