Fujifilm GFX100 II: “surgically accurate AF” = marketing masturbation... 35-70mm still focuses badly at INF and otherwise
Related: focusing, Fujifilm, Fujifilm GFX100 II, Fujifilm medium format, Fujifilm mirrorless, Live View, medium format, Other World Computing
Fujifilm marketing material claims:
GFX100 II brings a new 102-megapixel sensor “GFX 102MP CMOS II HS” with a readout speed that is about two times faster than GFX100S. Combined with X-Processor 5, GFX100 II is able to achieve a high continuous frame rate of up to 8fps, surgically accurate AF, and advanced video features that have never before existed in any previous GFX System or X Series camera.
Perhaps “surgically accurate AF” is true for some lenses of high speed eg the optically fantastic Fujifilm GF 55mm f/1.7 * and under some easy conditions. Indeed, so far the 55/1.7 has shown focusing accuracy that is as good or better than all my prior Fujifilm medium format experience.
However, I have also seen, in 100% magnified Live View, obvious out-of-focus errors. These are relatively rare but they *do* occur. You cannot rely on Fujifilm autofocus for any critical landscape work at INF focus in particular. I do use the AF in magnified Live View with the 55/1.7, but only because I can check the focus at 100%— far easier now with the excellent EVF on the GFX100 II.
* The GF 55/1.7 is one of Fujifilm’s noisiest and fidgety lenses, unnervingly-so in use, similar to the 80/1.7. The experience feels like some clunky thing. Just try Play and then going back to shooting... what in heck is that lens doing?! It's unnerving.
But as for the Fujifilm GF 35-70mm f/4.5-5.6: autofocus accuracy at INF remains a demonstration of major-error autofocus, easily proven by focusing manually and noticing an obvious improvement in 100% magnified Live View—and even with the increased depth of field of f/8—which means a major AF error. Behavior is much better at center, and much worse towards the outer zones. It’s not always off, but often is. Bottom line is that you had better manually focus at INF if you want a sharp image.
This all matters a lot for focus stacking: the GFX100 II still has that destructive Focus BKT bug of consistently failing to reach INF focus (55/.7 included). Which means you have to get that INF frame for a focus bracket and you cannot rely on AF to get it for you. Fujifilm have not done their homework in spite of their marketing gaslighting.
