Face Detect AF quirks... any help?
 

Like others, I have parfocal issues with my XF300 (ie: if I zoom in to focus, then pull wide, focus shifts) so my usual focussing techniques are unreliable.

Some members reported the Face Detection mode of AF is a workable solution, and indeed when I can get it functioning it seems to track faces beautifully, and does a great job.

Trouble is, sometimes I just can't get the face detect boxes to come on, and it drives me nuts. I can't figure out why this is.

I will switch Face Detect on in the menu, shoot with shutter higher than 1/25 (required) with correct exposure and good contrast, but the boxes just won't come on for a nicely framed subject. This happens 80% of the time when I try the mode. Then, on other occasions with an ostensibly identical setup, it works like magic?

Is anyone else having this issue? Any quirks I should know about?

Much appreciated,

Josh

I'm the one who was rather vocal about the face detection. I did 4 shoots this week and noticed one thing.
One of the shoots was outdoors in the sun and when the talent was backed by a light colored or brightly lit background the face detection hunted a bit, maybe a second or two, but always found the subject.
Two shoots were greenscreen and it locked on immediately, never missing a beat. The other was indoors with controlled lighting and it always nailed the focus.
One thing to check is in the menu settings, make sure you're on instant AF rather than normal. Normal was pretty slow.
If that turns out to be the issue, youre in for a pleasant surprise! I'll keep my fingers crossed! ;)

Just how bad and common is this para-focus issue?

Thanks Robert.

Finally figured it out! Face Detect disengages when you use the Waveform monitor (which I tend to have on by default) - this isn't mentioned in the manual. But yes, it works like magic and once on it's extremely robust / useful, and picks up faces with ease.

Pity it can't be used at the same time as the scopes, which I'm also a big fan of.

Glen: the focus shift can be very bad indeed, rendering shots useless. Is it the case for all XFs under all circumstances? I don't know (others have reported their experiences in more detail in earlier threads), but I don't trust my XF to hold focus through the zoom range - sometimes it's obvious enough that you can see the focus being lost in the VF, other times I only see it back in the studio. It's my only real issue with an otherwise great camera, so if I'm in the field without an external monitor I intend to use Face Detect when possible, which really is quite dreamy. Even with peaking/magnification, it can be difficult to nail focus on wide shots with the 4" VF.

Ahh! That would explain why I haven't seen the issue you had. I use the scopes/waveform as a setup and quick check then turn them off when recording. As for the focus issue, I have it too so it must be all the XFs. Hasn't affected me since I use the AF mode most of the time. when I want to play with focus myself, I usually grab my 7D! ;)

OK, this focusing issue sounds like a bad defect. Images should never go out of focus when you zoom out. If this is a manufacturer's defect, the cameras need to be recalled and repaired.
I am seriously considering switching to the XF300, but if all my shots end up out of focus simply by zooming out, this cam won't do me any good. I sure as hell don't want to depend upon auto focus to get my shots, nor would I want to discover this problem after the shoot, in post production.
Has Canon fixed the problem? Can it be caused by zooming out to the widest point and the images are a bit soft? If Canon refuses to recognize this as a wide ranging issue, and there are many of you with cameras that share this defect, then a class-action lawsuit might be in order. Maybe you guys with defective cameras should compare serial numbers, time and place of assembly, etc.

I used a BBC XF300 last Friday and there were no focus issues after zooming out.
I did have peaking on as well and this would have shown any focussing discrepancies.
A delightful camera to work with - Canon have got it very, very right.
Be ordering mine pretty soon!

I have not noticed any problems along these lines with my XF305. Focus holds perfectly during zooms -- or I would have sent it back for a refund the first day I got the camera.

Thanks, Robin. I was hoping for your hands-on report. I'm glad you like the camera.

Doug, I agree completely. If defective, I would send it back in a heartbeat.

I'm sorry I hijacked this thead. The Canon rep I was dealing with never sent me the XF305 demo he promised, so I try to get as much info on this camera as possible. Obviously a focus defect would arouse my interest.

Reinhard sent his back to Canon and they claimed they couldn't replicate the problem:
http://www.dvinfo.net/forum/canon-xf...ems-xf300.html

Yet several of us on this forum have noticed the same phenomenon - for those of you who aren't experiencing it, count your blessings :-) I've owned many 1/3" cameras (Z1, Z5, XL-H1, XH-A1 among them) and never encountered this, but it's a very clear issue with my XF300.

In my case, I need my camera for everyday work and can't afford to send it to Canon New Zealand (who are notoriously slow and may take weeks to verify the problem) only for it to come back with the same issue. It's annoying, but can be worked around.