Is autofocus on the AF-100 usable at all?

A

antonyoung

Active member
I've seen tests of all kinds of stuff from people with access to the camera, but a test of the autofocus is conspicuously absent. I can't find anyone with a GH2 in stock, but I tried the 14-140 in a store on the GH1 in continuous focus mode and it was horrible. Just sat there hunting like crazy and never locked on anything. Is this still the case with the GH2/AF-100? Please let's not go into 27 pages about why nobody should or would ever use autofocus, I'm just wondering why there have been no tests of the autofocus and especially the face tracking posted. If anybody with a camera could test it and post the result I'd be grateful.
 
antonyoung said:
I've seen tests of all kinds of stuff from people with access to the camera, but a test of the autofocus is conspicuously absent. I can't find anyone with a GH2 in stock, but I tried the 14-140 in a store on the GH1 in continuous focus mode and it was horrible. Just sat there hunting like crazy and never locked on anything. Is this still the case with the GH2/AF-100? Please let's not go into 27 pages about why nobody should or would ever use autofocus, I'm just wondering why there have been no tests of the autofocus and especially the face tracking posted. If anybody with a camera could test it and post the result I'd be grateful.
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This is a good question. While some might be ready to say real shooters don't do autofocus, this lens system is not like a $20K fujinon eng lens. The autofocus might be very valuable on a lens like this when we may need to shoot in situations with some of the challenges of ENG.
 
With AF100 and ENG needs, I think a B4 broadcast lens is the best option. There are some adapters to mount they and with the "FullHD zoom crop" function on GH2 and AF100, it gives you a f/1,8 zoom lens!!! Really, ENG shooters don't use autofocus, but 2/3" cameras gives you more DOF and it's easier to focus. Anyway, with broadcast lenses it's easier to focus than any photo lens.

Byez to All
 
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Koitz_roller said:
With AF100 and ENG needs, I think a B4 broadcast lens is the best option. There are some adapters to mount they and with the "FullHD zoom crop" function on GH2 and AF100, it gives you a f/1,8 zoom lens!!! Really, ENG shooters don't use autofocus, but 2/3" cameras gives you more DOF and it's easier to focus. Anyway, with broadcast lenses it's easier to focus
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I'm unaware of any B4 option or capability for the AF100. Jan has already said there is not current provision for a powered zoom.
 
There is no zoom/crop on the AF100. A 2/3" lens on an AF100 is only going to result in a great big black vignette around the frame (unless you use the 2x doubler, in which case you'll lose 2 stops of light sensitivity and all your focal lengths will be doubled).

Describe the test the way you want it shot, and I'll try to get to it.
 
verzap said:
Could you use a B4/PL adapter with a PL adapter on the af100?
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Yes, and you can buy an adapter from bumkicho that mounts B4 on Canon FD (and use a Canon FD->m43 adapter). But you won't have any power for the lens, and it won't cover the frame on the AF100, so it's really only for the GH2.
 
So AF100 doesn't have zoom/crop option??? WTF!!!! I hope Panasonic add this in next firmware, because in case of B4 lenses it's a big lack.

Anyway, powered zoom it's easy to make, only to provide 12V to pins correct pins. I have mine working, although I'm waiting for a B4 to M4/3 adapter with tripod mount from ciecio7 at ebay. In addition, continuous f/3'6 it's not a bad aperture, although f/1'8 it's better :D.

Byez to All
 
Koitz_roller said:
So AF100 doesn't have zoom/crop option??? WTF!!!! I hope Panasonic add this in next firmware, because in case of B4 lenses it's a big lack.
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No it isn't -- it's the solution to the hell of aliasing and moire that DSLRs suffer.

You can have one or the other, you can't have both. If you want an alias-free image, you can't have the zoomed tele function. The zoomed tele works because it samples only a small patch at the center of the chip, at native resolution. The AF100's entire sensor is sampled all at once at native resolution. If you sampled a small central patch you'd end up with low-res standard-def or worse.

If you are willing to accept aliasing and moire patterns in your footage, then you can also have the tele crop feature. If you are averse to aliasing, then you use a proper OLPF and properly-engineered sensor, and that means that you cannot have the extended crop.
 
Barry_Green said:
Describe the test the way you want it shot, and I'll try to get to it.
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Thanks Barry, if you have time I'd be interested in:

-how it handles panning or sliding across a scene with close/medium/far objects
-how it handles walking through a room or flying through on a steadicam
-how face tracking works with one face at f4 (and f1.7 if you have the 20mm)
-how face tracking when the camera and subject are steady but the camera pans so the face moves to a different position in the frame
-how face tracking works with the camera steady but the subject moving both distance and frame position-wise
-how face tracking works with subject steady but camera moving (walking towards/away, frame position changing)
-how face tracking works with both camera and subject in movement
-how face tracking works with two subjects in frame
-how the camera autofocus deals with a scene where it has a focus and someone walks in front or the view gets occluded by some other object briefly
-how the autofocus works in a strong backlight, if it works at all shooting into the light source with heavy flare

The AF in AF100 is for autofocus is it not? I'd love to see what it can actually do (or not do).
 
Igelkott Film said:
The f1.7 20mm does not have AFC at all, not just a little bit.
Push auto-focus or manual man..
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Fantastic, I already have the 20mm and I prefer push AF, it's the best compromise between staying in full control of your focus and automation.
 
Barry_Green said:
If you are willing to accept aliasing and moire patterns in your footage, then you can also have the tele crop feature. If you are averse to aliasing, then you use a proper OLPF and properly-engineered sensor, and that means that you cannot have the extended crop.
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I don't know so much like you about this type of cameras, but if you crop a 1920x1080 frame from a 16 Mpx picture from GH2, it doesn't present any aliasing. What it's difference between this "software cropping" and make on camera? Maybe GH2 have a low-pass filter and AF100 haven't.

Byez to All
 
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