Viltrox PFU RBMH 85 mm f/1.8 STM review - Autofocus

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Viltrox PFU RBMH 85 mm f/1.8 STM

14 October 2019

Arkadiusz Olech

10. Autofocus

A plan to test the autofocus of the lens on the Fujifilm body was one of the reasons why we ordered two specimens of the tested Viltrox with different mounts. That system, contrary to the Sony one, didn't reveal specifications of its mount and that's why there is a huge deficit in Fuji X lenses, manufactured by independent producers and equipped with an autofocus system. The Viltrox is an exception so we were very curious about the quality of its focusing mechanism.

While cooperating with the Fujifilm X-T2 the said autofocus is silent and quite efficient. Running through the whole distance range and confirming the focus takes about 0.6 of a second and that value doesn't depend on the direction. Focus hunting was rare but we did notice it several times – of course then the focusing process took longer.

It's worth mentioning that the X-T2 features an autorocus system with not only face but also eyes detection. We tested that function in most extreme conditions, employing f/1.8-2.0 aperture with the shallowest depth of field. The final effect could be called sensible. We expected a lot of misses (especially that, in addition, our model proved to be very energetic and hardly patient enough) but still about 50-60% of shots were quite useful and acceptable.

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In the case of ordinary studio or outdoor sessions, while photographing solid objects, the autofocus performs sensibly well even if you can notice slight differences in sharpness of several consecutive photos. In our opinion it proves the mechanism is not perfectly repeatable.

When it comes to speed and ergonomics, the lens joined with the Sony A7R II performed similarly to the other specimen, attached to the Fuji X-T2. Perhaps the repeatability and accuracy was slightly better in the case of the Fuji X model but still the ergonomics seemed to be worse than that of the Sony FE 85 mm f/1.8.

Both models, used in our test, didn't have any noticeable problems with front or back focus tendencies.

X-T2, f/1.8