After almost a month's research and development, Fringer EF-FX smart adapter prototype's PDAF performance has been further improved.
Unlike Sony E mount cameras, Fujifilm X mount is quite complex in PDAF support. More than two years ago, when A7r2 introduced phase detection AF (PDAF) for adapted lenses for the first time, I spent a night to find out the key mechanism and in very short time let my Contax N-E adapter become world's first third party smart adapter supporting PDAF on mirrorless. Now I finally find the way to make X cameras do the same when adapting EF lenses. All the PDAF points on CMOS, not only the central one, but also the others around it, are all working properly, whatever the lens is wide or tele, zoom or prime and whatever the aperture is set wide open or stopping down.
Although the firmware of smart adapter for GFX50s can be easily modified to support X mount as what some other smart adapter manufacturer probably is doing , it doesn't support PDAF. Compared with CDAF (contrast detection AF), PDAF is a performance leap. Thus, I developed the new version specifically for X mount. I made a short video to demo the AF-C zone focusing performance when PDAF is enabled. The lens is Sigma 30/1.4 art (for EF mount) and the camera is X-T2. Remember that S30/1.4A has a bad reputation for its slow AF speed.
The demo video:
In addition to that, I also did some real field tests. Using a EFs 55-250/4.0-5.6 IS STM lens and X-T2 camera, I tried continuous shooting on a moving vehicle towards the camera. I set the AF mode to zone and AF-C, continuous shooting mode to CH, and shutter mode to electronic only. The lens was at 250mm/F5.6.
I shot 34 photos in less than 4 seconds with a rough speed of 10 frames per second.
The following animation GIF is composed of all those photos.
To better check its focusing accuracy, a small area was cropped from each frame to do comparison. let's see the crops of 15 continuous frames.
As you can see, it's not perfect. several of them were out of focus. But most, i.e. about 80%, of them were OK. I guess that's a not bad performance for zone AF/AF-C with speed of 10 frames per second.
The Fringer EF-FX smart adapter (production version) is expected to be released on early 2018.
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