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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 27th, 2006, 03:02 AM   #46
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Quote:
Originally Posted by Tom Roper
Wrong!
I'm talking about the back-focus setup. When you zoom a lens in-to, or out-from a stationery object the focal point of the lens should remain constant, ie. the object should stay in focus.

I'm not saying that the autofocus should be inactive whilst zooming. What we're talking about here is an focus "aretifact" that occurs when zooming on static objects.

Quote:
Originally Posted by Raymond Toussaint
Q. The focus issue Alex described is repaired and gone. That is his word.
Q. Zoom and focus in AF together the same time (how often do you want that? or work that way, but that is another question, I never do)
1. Unfortunately I'd been a bit hasty is declaring ALL the focus issues gone. The pulsing happens on this camera too.
2. You're absolutely right, I barely EVER have the AF on - and we've all been taught that we shouldn't really be zooming in-vision (the human eye doesn't zoom).

My point is more to do with merchantable quality of goods. If Canon advertises a feature, then that feature should be usable. It is reasonable to expect that AF could be left on, as zooming in and out is normal behaviour whilst filming something. AF cannot be left on during very slow zooms on the long end of the lens, because it produces an unpleasant effect on screen.

It's like advertising a car that has self-leveling suspension, but not mentioning that you can't drive it up hills.
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Old December 27th, 2006, 03:29 AM   #47
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Quote:
Originally Posted by Raymond Toussaint
Q. The focus issue Alex described is repaired and gone.
Unfortunately it is not. Please have a look at my example clips I posted earlier.

Quote:
Originally Posted by Raymond Toussaint
Q. Zoom and focus in AF together the same time (how often do you want that? or work that way, but that is another question, I never do).
I do. I sometimes simply have no other choice since there is not enogh time to focus manually. Either AF or snapshot is gone.

I guess we all can live with this AF malfunction during slow zooms. But I completely agree with Alex that this pulsing is NOT what one would accept of any AF system - alll the less since Canon praises its design as new and revolutionary. The AF system of my former FX1 didn't pulse at all during slow zooms, so it never ruined a zoom shot like my new A1 does in AF.

Chris, as soon as you find the time please change the title of this thread, since the problem is NOT solved. The actual title is misleading for users - and for Canon, when they browse through user feedbacks to get input for a coming firmware update.
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Last edited by Michael Mann; December 27th, 2006 at 03:59 AM.
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Old December 27th, 2006, 06:05 AM   #48
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Quote:
Originally Posted by Raymond Toussaint
<snip>
Zoom and focus in AF together the same time (how often do you want that? or work that way, but that is another question, I never do)
<snip>
Actually I have to admit that I do this sometimes at weddings. A slow zoom in on the bride and groom can play quite nicely, but a kung fu snap zoom would probably be... unwelcome. If I'm in manual focus and off a bit, it won't really show at the wide end - but would become apparent and quite awkward as the zoom nears the subjects. In this case its not something you can correct during the zoom since the lens doesn't allow you to focus while zooming.

Now having said that, let me clarify that I perceive this phenomena at 24F and don't plan to shoot weddings at that frame rate. I'd shoot a typical wedding at 60i unless requested otherwise, and I have not noted the pulsing zoom at 60i so I'm not concerned. However, since the pulsing focus is possibly related to the AF sampling rate, I could see this being an issue for PAL users under more typical shooting scenarios as opposed to NTSC users.
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Old December 27th, 2006, 06:14 AM   #49
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Alex his camera was faulty and is replaced, he did not have the going in - out focus problems anymore. Canon fixed that matter. That you see minimal pulsing on the big screen while doing zoom in with AF on, is something you can avoid.

Michael: there are many very happy A1 shooters at work on the moment I did not hear anyone complaining like you do. You complain about everything.

Can you try to shake the camera hard (what you did before) while zooming with AF on at the same moment, and describe what is happening? If you can't see it on monitor, try a 42" screen, please report your findings.
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Old December 27th, 2006, 06:21 AM   #50
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Quote:
Originally Posted by Philip Williams
If I'm in manual focus and off a bit, it won't really show at the wide end - but would become apparent and quite awkward as the zoom nears the subjects.
If you track in and zoom in at the same time to 'soften' the starting point of the track you can do that with autozoom. You can (pre) manual focus and/or use the PUSH focus button to help you out.

Is done many times, professional lenses don't have autofocus, but have autozoom. Canon gave us the 3 ring lens, use it.
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Old December 27th, 2006, 06:37 AM   #51
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Quote:
Originally Posted by Alex Leith
My point is more to do with merchantable quality of goods. If Canon advertises a feature, then that feature should be usable. It is reasonable to expect that AF could be left on, as zooming in and out is normal behaviour whilst filming something. AF cannot be left on during very slow zooms on the long end of the lens, because it produces an unpleasant effect on screen.

It's like advertising a car that has self-leveling suspension, but not mentioning that you can't drive it up hills.
Hear you. But even zooming in the shot is something I only do for dramatic reasons, combining that with AF... I think normal AF is workable if you follow a moving object or pan from figure A to B and need to do refocus. If you use a mattebox, the AF Instant focus version is blocked anyway, so only nomal AF is working. And it works!

I think that Canon was so happy with the 'speedy AF two way instant focus system' that the marketing department only told you the goodies.. But I remember the Panasonic HVX200 without saying what the real CCD resolution was...
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Old December 27th, 2006, 11:12 AM   #52
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Quote:
Originally Posted by Raymond Toussaint
Michael: there are many very happy A1 shooters at work on the moment I did not hear anyone complaining like you do. You complain about everything.
We all know that the A1 is a very good camcorder, that goes without saying. I am a (quite) happy A1 user myself. But I don't think it would bring users in this forum any further if we only sing our praises. To know the cams limitations - that's important as well. Because maybe weak points could get fixed in the future.

Therefore my intention is not to complain but to observe and to share. Period. And if there are weak points - I don't want to draw the curtain over them.

Quote:
Originally Posted by Raymond Toussaint
Can you try to shake the camera hard (what you did before) while zooming with AF on at the same moment, and describe what is happening? If you can't see it on monitor, try a 42" screen, please report your findings.
What exactly do you want me to find out? Please explain, thank you. (But I don't have a 42'' screen).
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Old December 28th, 2006, 09:07 AM   #53
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Informed Canon about focus pulsing problem

Meanwhile I had a phone call with Canon Service in Germany.
The service member promised to watch the demonstration clips (http://www.filefactory.com/f/f5656740836b15ad/) to unterstand the problem. And he promised to call me back as soon as possible.

I will keep you informed ...
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Old December 28th, 2006, 09:16 AM   #54
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Thank you Michael. I look forward to hearing what Canon have to say about this issue.
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Old December 29th, 2006, 03:47 AM   #55
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Received a phone call by Canon

I just received a phone call (conference call) by a Canon Service team in Germany:

(1) They had watched the two demo clips and they DID notice the focus pulsing problem. They asked me about further technical details (distance to object, f-stop).

(2) Their first guess was that the two clips show EXTREME lighting situations: low contrast boy in front of low contrast tapestry; low lit woman in front of bright background lighting. (I agreed but replied that the problem occurs under NORMAL lighting/contrast situations just the same.)

(3) Their second guess was that the problem might occur in long telephoto focal lengths and/or open iris zoom shots only. (I replied that more or less depth of field sure makes this problem less or more visible, but the pulsing DOES NOT DISAPPEAR in medium focal length and/or medium f-stop zoom shots.)

(4) Their final guess was that this AF pulsing is NOT FIXABLE - not even via firmware update - but probably is related to the design of the AF system. (I put into perspective that there ARE cams on the market that do not show this problem, e.g. the FX1.)

(5) The Service team promised to forward the information to Japan.


Chris, could you please change the title of this thread, since it may mislead fellow users as well as Canon when browsing through this forum. The problem remains NOT SOLVED. Thank you.
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Old December 30th, 2006, 10:32 AM   #56
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I have exactly the same focus problem with my A1 (PAL). There is only one solution: disable AF and use manual focus. I would be also happy if Canon could fix it.

Nevertheless, the camera is really professional...
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Old December 30th, 2006, 10:43 AM   #57
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Thanks Michael for your report. I suspect current owners are not likely to see a fix, so as Gabor says, the only workaround for this "quirk" is to keep AF off.

In almost every other respect this is a great camera.
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Old December 30th, 2006, 11:23 AM   #58
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Quote:
Originally Posted by Michael Mann
I just received a phone call (conference call) by a Canon Service team in Germany:

(4) (I put into perspective that there ARE cams on the market that do not show this problem, e.g. the FX1.)
Since I owned the Z1, I've got some perspective on that too. The Z1 could not auto-focus when shooting into the sun or strong backlighting. I think this is a case of selective memory where the grass always seems greener on the other side of the fence.

Shooting low contrast subjects at long focal lengths it seems you lacked proof and were not convincing to the Canon Service team that this is a serious problem.

Nothing is more irritating than when someone with a problem gets replies from others who say "mine doesn't do that!" And while I don't dismiss the seriousness of the problem for you, for me it's not happening at all. So while I have no idea how many cams are affected, I know that not all of them are.

But if I felt as strongly about it as you do, I would return or sell the A1 and go back to the Z1. But no regrets here. The A1 picture quality and control is superior, even given some of the other limitations like the smaller LCD screen or lack of an OIS button. The eyes have it.
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Old December 30th, 2006, 01:07 PM   #59
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Thanks Tom for your input.

Just to be clear, you're saying that your A1 does NOT show any symptoms of focus "pulsing" at long focal lengths in AF mode (in 24F or 30F)?

Makes me feel a little miffed that I've managed to get two units in a row that DO show this problem.

Still like you say, the picture quality is so much better than my FX1, and I leave AF on so infrequently that in lieu of any response from Canon, I'm happy to live with the quirk.
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Old December 30th, 2006, 01:36 PM   #60
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Quote:
Originally Posted by Alex Leith
Thanks Tom for your input.

Just to be clear, you're saying that your A1 does NOT show any symptoms of focus "pulsing" at long focal lengths in AF mode (in 24F or 30F)?
I did not try 24F or 30F. No focus pulsing at 60i remotely resembling what you had in your first A1. Also your first clip, the one of the bag on the patio deck was not a long focal length. THAT test I tried to duplicate, i.e. a low contrast object from 8-10 feet and there was no hint of the extreme herky-jerky focus pulsing I saw in your video.

I will try 24F and 30F shortly and report my observation here.
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