Thread: Fujifilm Hybrid AF System with phase detection AF

There is an interesting discussion in DPReview about the newly announced Fujifilm's Hybrid AF System that adds phase detection AF to compacts cameras: Myth Buster: Phase Detection AF without a mirror?

What I liked the most was how well known user Joseph S Wisniewski predicted the system seven years ago, in what may be a good insight as to how the system works:

Or simply slant the wells (or offset the microlenses, probably an easier approach) of one CCD or CMOS cell in every 64. Won't bother the image much, but will give you 93,000 cells in a 6MP sensor that can sense focus. The Canon CMOS reads 18 million cells/sec, if just 1/64 of them were focus sensors, it it could read the focus 1,150 times/sec.

Actually, that might be a bit much, maybe 1 in 256 focus cells would be more managable.

If the offset microlenses on the focus cells cuase too much image distortion, interpolate around them the way you would any stuck pixel.

He also adds a lot of useful information in that thread, that I recommend you to read.

You can find another interesting conversation at 43rumors: Fuji HybridAF tecnology. Something Panasonic and Olympus should add as soon as possible

Now what we need is to see this system working in the real world (I'll update this thread as soon as I get to know something new). If it works, I think we will see it in mirrorless ILCs pretty soon.

Good find by ItsaChis in 43rumors.com (here) that may explain how a system like this works. It's a patent by Sony:

Image pickup device and image pickup

IMHO it's just another of the countless marketing tricks. they just call it "phase focus" while couple of dedicated pixels surely cannot handle full phase AF service.
Also direct embedding of complete phase AF support would exclude from normal exposing hundreds of pixels, such a gap by no means can not be interpolated without huge quality loss

Couple? Well, no, there are tens of thousand of pixels dedicated to focus, as sugested by Wisniewski in the forum and as stated by this french magzine:

Fujifilm FinePix F300EXR : précision sur l (Google Traduction)

You should read both the Sony patent to see how a system like this may work (the images of the pixels are very self-explanatory) and the DPReview thread for ideas on how those pixels may be arranged and why they won't affect the final image.

Let's wait to see how it works in the real world.

arojilla thank you, now it's more clear. Collimation just was transferred to micro level of main shooting matrix.
Still not good on 1/2" matrix because of diffraction. Also because of light partially cut some quality loss still expected even in case "focusing" pixels do participate in exposure process too.
All the same I think it's better to wait for photosamples and further leakage of technology details.

Yes, let's wait. No doubt this can be a very big improvement for mirrorless cameras. And maybe we see other companies trying the same with different technologies soon. I guess this is just the first step in that direction.

Oh, and you are right about the sensor size, too small (almost for anything).

In this page (in japanese) they talk about the new F300EXR and its new Hybrid AF. There are two videos, one showing the Fujifilm's focusing speed and the other the speed of a Ricoh CX1. See for yourself.

There is a new preview, in spanish, of the F300EXR and they confirm that the new AF system works: the lens doesn't 'hunt' like most cameras with contrast detect AF and there are no... how to say this in english... false positives? Well, when the camera says it has focused but it's not true.

Fujifilm FinePix F300EXR: toma de contacto y muestras

The most interesting is that they compared it to the Panasonic G2 and they say there are almost no differences in their focusing speed but sometimes the Fujifilm is faster. Not bad for a compact with a slow lens and the first system of this kind.

Fujifilm's phase detection system explained by DPReview.