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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 July 17th, 2009, 04:31 PM   #1
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Another Ghosting problem

This is totally unnacceptable..

Can anybody please help me out here...
I freelanced a ceremony several days ago..It was SD and 4:3. Upon playback, the panning and zooming created a ghostlike behaviour on the whole image. To add insult to injury, the frame was softened (due to the nature of the ghosting)..Of course, i was on tripod and OIS is always turned off...Except for auto whitebalance, i was in total manual mode..

I've had this before, during my HD filming, but have always assumed that it's a product of Mpeg artifacting..I was in denial. It doesn't show up on the viewfinder at all...
But this just tops the cake. It's not normal..Since i can't produce the SD stills, i'll show you my HD equivalents.

As a side note to people interested, i switch back and forth between OIS on/off, depending on my situation..I'm never go lower than 60i and aperture is usually opened up all the way (due to lighting circumstances). Exept for an auto whitebalance, i'm usually in Auto mode with the Exposure lock turned ON, once i get the right exposure.

I've also allowed for Deinterlaced sreenshots from the timeline just for further analyzing. This is definately NOT an interlacing issue, for anybody thinking otherwise..

Here's some screenshots.
Attached Thumbnails
Another Ghosting problem-dance-deinterlaced.jpg   Another Ghosting problem-dance-interlaced.jpg  

Another Ghosting problem-mic-deinterlaced.jpg   Another Ghosting problem-mic-interlaced.jpg  

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Old July 17th, 2009, 05:04 PM   #2
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Hi Peter.............

Seeing how dark those pictures are, I'd say that even with the Aperture maxed out open, the camera is having to set a shutter speed so slow, a tortoise would leave a smear trail.

I don't know what the slowest two shutter speeds are on a NTSC A1 but I'd really not use them on anything that's moving (unless, of course, you're trying to get that look).

Think it might be time to invest in some lights.


CS
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Old July 17th, 2009, 05:56 PM   #3
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At a shutter speed of 60i, there is really nowhere else to go without smearing. Although this was a bit of an extreme situation, the SD shoot of late had plenty of light, but exhibited similair results during zooming.

Of course, i could try to bump up shutter speed, and bring up Gamma in post, but i've seen low light footage from other XH A1 owners, and it didn't seem as bad as mine.

My Panasonic GS400 never showed this kind of ghosting, and it was horrible in low light..
I've got a Swit 2010 from 5-6 feet away, and it should be good enough to avoid what i'm getting..

I've got to get back to some serious testing and find out button for button, what causes this anomaly...
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Old July 18th, 2009, 12:48 AM   #4
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Hi Peter. Are you using noise reduction? One of the noise reduction types (I forget which) causes image ghosting.

One tip for low light shooting is to use the PFVision preset (see thread below). This seems to work great without any NR, although of course there are limits to how dark you should try to shoot without adding lights. (Unless you want that noisy washed-out look. :) )

http://www.dvinfo.net/conf/xh-series...-included.html

Richard
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Old July 19th, 2009, 09:52 AM   #5
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I'm not familiar with any noise reduction options?

As a rule of thumb, i like to shoot with presets turned off. It's a lot easier and safer for me to CC in post, rather than having to worry about losing pixel information that i'll never get back...

But nonetheless, i'll give it a try..
If i can get some footage from the SD shoot from a few weeks ago, i'll try to post some samples..The ghosting/jittery footage was all on tripod, with plenty of lighting...
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Old July 19th, 2009, 01:33 PM   #6
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Er, Peter.............

Can we clear something up here?

"At a shutter speed of 60i" makes no sense whatsoever.

60i is 60 interlaced fields per second (which is a field/ frame rate) and no, zero, nada, nothing to do with the shutter speed.

If you mean 1/60th of a second, then that's a different story, but it isn't 60i.

Sorry if this seems picky, but if we're not talking the same language..................


CS
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Old July 19th, 2009, 04:48 PM   #7
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Hi Peter,
As Chris has pointed out, shooting in 60i has nothing to do with the shutter speed, & i think that is where your problem lies. If you are shooting in AP mode, then the camera will likely be setting the shutter speed to less than 1/30th of a second. Judging by the (lack of) light in the frame grabs, this is the most likely cause of the ghosting you are seeing in your footage.
Try to set the camera up in manual mode & set the aperture to get the most light into the lens, & shutter speed to not less than 1/30th. (The little wheel to set the shutter speed is just behind the aperture ring on the lens on the left hand side of the camera). Make sure auto gain is turned off & try not to use a gain setting more than 6dB, lower preferably. I would also try the PFVision preset as Richard has suggested as it is a very good low light preset.
Hope this helps,
Bryce
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Old July 19th, 2009, 11:11 PM   #8
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Quote:
Originally Posted by Chris Soucy View Post
Can we clear something up here?

If you mean 1/60th of a second, then that's a different story, but it isn't 60i.

Sorry if this seems picky, but if we're not talking the same language..................
CS
Oops....Yes, of course, what i meant was 1/60th shutter speed. I would never dare go to 1/30th shutter speed. You have every right to call me out on that.

When i first used the camera for a dance recital, i couldn't help but notice there was colour smearing on the dancer's extremities. I'm wondering if Canon uses some sort of chroma shifting during interlacing to save on bandwidth...Lighting was exceptional...

Although i don't know what AGC has to do with my smearing problem, i definately keep it off. Yes, i will definately look into the PFVision preset..Thank you Bryce.

I don't mean to drag this out any farthur without further testing, so i'll try and keep my replies to a minimum. At least until i can mimic this strange behaviour..

Thanks for you patience.
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Old July 20th, 2009, 06:49 PM   #9
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I am having a similar issue. I just sent my year and a half old A1 to Canon today. The last couple things I've shot have had some ghosting/smearing issues very similar to yours. It started off subtly then a week ago got a lot worse. I mostly shoot 24f, 1/48th, NR turned off and OIS turned off when I'm on sticks. I did a bunch of tests at 24F and 60i with varied shutter speeds up to 250th. It not only shows up on the footage but on an HD monitor as well. I also tested it in broad daylight and it was apparent. Canon basically told me that it sounds like the sensor is going out. Hopefully yours isn't the same.
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Old August 8th, 2009, 10:11 AM   #10
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Auto Focus is the main culprit

After doing some more testing, i've found a combination of things that are creating my problems..

Firstly..
As a rule, I know autofocus is not desired, but in run'n'gun situations, it's a necessity. You can't convince me otherwise..
My camera, is fighting to keep focus. Even on objects that clearly don't need focus adjustment. Once the camera pans or leaves telephoto the image totally jumps around.
Example, I perfectly focused on a fairly lit wall, and upon panning, the focus goes out of whack. To add, there was no foreground or background to trick the sensor.
Ironically, my findings are that the Image stabilizer (on/off) has little effect on this.

Secondly..
Low lighting also effects focus. I shot outside, (ND filter set), and the sensor works as expected. For my original images (above), i've come to the conclusion that combining low-light plus panning plus autofocus produces my smearing.

Thirdly..
My perception also, is that this is focus hunting is more noticeable shooting DV 4:3 than in HDV..


So my question..
Is there anyway to adjust the sensitivity of my autofocus? It's totally unnacceptable behaviour under the circumstances..

Aside from the above images, my focus sensor shouldn't be going crazy on flat objects with ample indoor lighting.
I'd also like to add, i've got IAF enabled via suggestions from the manual.

Any suggestions, or is this going to be a Canon service call??
Thanx....
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Old August 8th, 2009, 03:57 PM   #11
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I hate to be the pessimist, but it sounds like your camera is broken in some way, shape or form. I own and shoot weddings on an XH-A1 and while I know about the issues you're talking about in your posts, I have never experienced them directly. Well, I have had some auto-focus issues but only in low lighting situations, like receptions, which tend to be dimmed down to create a mood. I have never seen the XH-A1 ghost or smear in HD or SD even with poor lighting.

I'd give them a call.
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Old August 8th, 2009, 05:33 PM   #12
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I guess Mike hasn't posted since he said he sent his camera off to Canon.They replaced the optical block. It was a sensor problem. It's a good idea to send yours in ASAP, and include the tape or a copy of it and time code noted so the tech can see exactly what you're talking about.
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Old August 8th, 2009, 08:02 PM   #13
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Auto focus has always been unreliable when lighting is poor, or when the subject lacks features (e.g. a flat wall). If you have to shoot in these conditions it is much better to use manual focus.

But to go back to the original post, if the only thing in auto mode was the WB, presumably the focus was in manual?

Anyway I don't see how the symptom "the image totally jumps around" in Peter's latest post could be due to focussing issues. Better get someone to take a look at the camera and see if it has a problem.

Richard
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Old August 13th, 2009, 07:01 PM   #14
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Sorry I haven't been on here in a little while. Well I sent mine in and sure enough they had to replace the CCD assembly. Canon service was great about getting back to me within the 5 days promised being an XH owners club member. At FIRST I was very impressed with the service center and their quick repair but the customer support center just plain stinks. It seems they have no working knowledge of the camera beyond the troubleshooting manual they read off of their screen. I spoke to a couple different people and finally got a repair authorization.

So I get my camera back in 4 days which was fantastic. I give my mentor and life counselor Bill Pryor a call. He recommends I check the back focus. Long story short. THEY DIDNT ADJUST THE BACK FOCUS!!!! So I am now troubleshooting this with Canon customer support which I would have better luck asking my neighbor who repairs lawnmower engines for advice. They had no idea what adjusting back focus on a lens was. They kept telling me to power down the camera and do a reset. I am now waiting for another box to send my A1 back to Canon.

If anyone has a super secret number to someone at Canon that has a working knowledge of their camcorders I would greatly appreciate it. And if you live in the greater Austin metro area I will gladly hand over a case of your favorite beer.
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Old August 13th, 2009, 07:55 PM   #15
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Life counselor. Sheesh, you're in more trouble than having a bad back focus.
They should have checked that out before returning the camera, since the put in the whole new chipset. I trust you made the point that there was nothing at all wrong with backfocus before you sent in the camera.
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