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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old December 3rd, 2008, 01:43 PM   #1
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Instant Autofocus problem

On several occasions I have had a problem with my XH-A1 focusing on subjects far away, (ie further away than say 5m), the resultant footage is blurred as if it has focused on something much closer, this is when the camera is set to I-AF autofocus, close up subjects are fine and it doesn't occur all the time. Setting the AF to Normal doesn't have the same issues and Manual focusing is fine. My Canon HV20 will focus fine under the same circumstances. This is outdoors without anything in the scene that would distract the autofocusing, has anyone else had similar issues ?
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Old December 3rd, 2008, 02:06 PM   #2
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Brian,
I am having the exact same problem. Anytime I have a complicated backgroud, the autofocus chooses the background. Even when I manually adjust the focus, it pulls it back to the background. Is there somethign wrong with the camera? Or is it just how it works.
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Old December 3rd, 2008, 03:07 PM   #3
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Brian, Bill............

Brian - can you run that past me once again.

I can't make out whether you're saying it can't/ won't focus at a distance or ditto close up.

Bill - Because of the above I can't make out whether you have the same issue as Brian, tho' it doesn't sound like it.

However, your issue sounds like something not altogether undocumented.

If you dive into the A1'a menu and go to "Display Setup" and set "Markers" to "Grid", you'll get two horizontal lines and two verticals on you're LCD in any shooting mode.

It's my experience that unless the central "box" made by these lines is nearly filled by you're chosen target in AF mode, the camera focus is quite likely to go hareing off into the background instead.

This can be used to quite stunning effect with a bit of thought.

Example: A (real close) close up of a sea bird sitting on a rock with the (totally out of focus) background miles away.

Bird occupies most of the "box".

Bird flies off.

Camera effortlessly gives the rock the flick and focusses out to the background which swims into perfect sharp focus.

Looks magic and nigh on impossible to pull off manually.

The beauty of this is that if the same or another bird flies in and lands on the same spot, the camera will just as effortlessly focus back into the bird thus totally blurring the background again.

The down side is exactly the same as the upside unfortunately.


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Old December 3rd, 2008, 05:26 PM   #4
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Chris,
In general I'm having trouble finding focus at all. I have been using these for almost a year now, and all of a sudden in October, my primary cam doesn't seem to hold focus. And I say that because when I'm testing it, it looks fine. But as I'm working, things are just plain out. My main issue comes when I have a subject against a complex background like trees or a window. Or if I have a dark subject against a light background, or vice versa. The auto seems to always pull to the background, no matter what. If I pull it back to the subject, it goes right back. There's a few examples of the focus issues in this highlight...
Bill
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Old December 4th, 2008, 07:46 AM   #5
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My issue seems different to Bill's, if there is a subject close to me the camera has no problem focusing on it, but if the subject is further away (typically some people stood say 15 foot [5 meters] away in church grounds with trees etc in the distance) then sometimes (and quite randomly) in I-AF the camera hasn't focused, this I only become aware of when I get home and look at the footage (the viewfinder isn't large enough to tell at the time), in these circumstances it is difficult to ascertain what it has focused on as the the WHOLE scene is out of focus .. it as if the camera has not been able to focus on anything in particular and give up (taking a wild guess), in Normal AF there is not usually a problem.
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Old December 9th, 2008, 12:17 PM   #6
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Don't anybody get offended by this comment, but have you guys made sure your IAF windows are perfectly clean? I had a nearly invisible speck on mine that caused major issues with IAF.

Bill - Are you saying that you manually override the AF with the focus ring, and then the focus drifts back to the wrong setting? Or are you having focus drift with AF turned off completely (not just IAF turned off)?
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Old December 11th, 2008, 07:40 PM   #7
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Hey Ken,
Sorry it took me so long to get back to you. I have been really slammed. Yes, if there's a complex background like leaves or a pattern wall. Or if it is a high contrast situation like a light colored subject and a dark background or vice versa. It will pull focus to the background. I pull it forward and the camera pulls it back. I just got a call from a guy who's been editing some stuff of mine asking me if I have been using "manual focus" because everything's just a little off. That'll send a chill down your spine. I'm looking at a rock show that I shot on Saturday night and it looks perfect. Tack sharp. Not much contrast, but tack sharp... This editor is working on SD stuff for local TV. That worries me alot. Anyway, I also founf that my autofocus sensor was gooped up like crazy. That could've done it too I guess...
Bill
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Old December 12th, 2008, 10:46 AM   #8
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Quote:
Originally Posted by Ken Wozniak View Post
I had a nearly invisible speck on mine that caused major issues with IAF.
That's a good point, you wouldn't have thought minute specs could affect it, I've also previously had issues to specs on lens filters where camera's have actually autofocused on them, I now only use them in situations where they are very necessary.
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