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Old March 21st, 2010, 04:18 PM   #1
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Strange lines/rows when reading the tape from Canon XL1

Can somebody explain this ?
And can somebody help me to avoid it ?

Thank for you help...
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Old March 21st, 2010, 11:11 PM   #2
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Hi Erwin.................

Hmm, well, can't say as I've ever seen anything like it and am at somewhat of a loss to offer a rational explanation with the information provided.

As it appears to be two merged data sets, the first question has to be: "where is the second data set coming from?"

As you know what was previously on the tape (if anything) and what you put onto it immediately preceeding this merging happening, perhaps a bit more explanantion of circumstances would be in order.

If you can reckognise either (or both) of the data sets as having at one time being on the same tape, that would be a start.

Then of course there is the obvious question: Is this data previously recorded but not overwritten when subsequently recorded over, or is it data from the same recording session as the last one?

A bit more info and we might get somewhere.


CS
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Old March 21st, 2010, 11:44 PM   #3
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Giving this even more thought...............

IF this is happening consistantly with every shoot you're doing, do this little test for us.

Shut down the camera. Insert a brand new, never before used tape.

Turn on the camera, leave the lens cap on and record one minute of pure black.

Rewind the tape to the beginning. Take off the lens cap and set the shutter to 1/30th and the iris wide open, aimed at a white wall in good sun.

Shoot for thirty seconds.

Rewind the tape. Play.

What do you get?

Now, rewind the tape. Turn off the camera. Turn it back on. Play.

What do you get?

Now, go back to the beginning and do it all again with another new tape, BUT, turn off the camera between recording black and white.

What you're actually trying to find out is whether you have a tape deck or a processor/ memory problem, hopefully the above will give us some pointers.

Problem is, what to do about either given the age of the camera.

More as and when.


CS
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Old March 22nd, 2010, 12:03 AM   #4
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Simple answer - clogged heads. Probably at the time of recording so the second "write" didn't fully cover the first. Seen it a million times. For those that haven't seen it before, this is TEXT BOOK.

EDIT: ok, not a million but this EXACT phenomenon is why I rail against mixing tape stock as I've had this happen to me.
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Old March 22nd, 2010, 12:21 AM   #5
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clogged heads : Thanks for giving it a name.
mixing tape stock : That's what I id before, but for the past 2 years I only use one brand and alway the same type.

It doesn't happen all the time. Sometimes I can do 2 or 3 tapes without the problem. But this time it happens a lot.

Can initializing the tape help ? (Prerecording it with lenscap on)

Thanks for the explanation.
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Old March 22nd, 2010, 12:25 AM   #6
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Quote:
Originally Posted by Chris Soucy View Post
As it appears to be two merged data sets, the first question has to be: "where is the second data set coming from?"

As you know what was previously on the tape (if anything) and what you put onto it immediately preceeding this merging happening, perhaps a bit more explanantion of circumstances would be in order.

If you can reckognise either (or both) of the data sets as having at one time being on the same tape, that would be a start.

Then of course there is the obvious question: Is this data previously recorded but not overwritten when subsequently recorded over, or is it data from the same recording session as the last one?
CS
Part of the frame is from the recording before I press the red button, the other part is the new recording. I didn't replace the tape. It's on the same tape that was a blank one from the beginning.
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Old March 22nd, 2010, 12:29 AM   #7
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Originally Posted by Chris Soucy View Post
IF this is happening consistantly with every shoot you're doing, do this little test for us.
CS
It doesn't happen all the time. Sometime I can do 2 or 3 tapes without the problem. But than it back. Most of the time, but not always, at the end oth the tape. The last 5 minutes. But the tape I use after the 'bad' one is just fine...

Can it help if I more clean the heads ?

Thanks for the reply.
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Old March 22nd, 2010, 12:38 AM   #8
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Well, I suggest you do the test...........

AFTER giving the heads a bloody good clean, hey, even three or four times if necessary.

If it's still happening, well, there's nothing for it but a professional clean, if you can find someone to do it.

If that doesn't fix it, there must be a hardware fault.

Thanks, Shaun, ain't seen it before, ever.

Couldn't reconcile what I saw with degraded head performance, under any circumstances.


CS
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Old March 22nd, 2010, 12:43 AM   #9
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I THINK it has something to do with 2 of the 4 heads on the drum getting clogged and thereby writing 50% of the frame anew... Used to get this with my Sony PD150 if I had to playback client supplied footage in the field. My deck is somewhat more robust but still has had it's "issues" over the years.

Besides changing tape stock, regular run-of-the-mill "dirty' issues such as not keeping cassettes in cases, smoking around tapes, dropping rum and cola on them can also cause clogging so it isn't automatically tape stock. As well, if your heads haven't ever been cleaned, well, tapes shed oxide over time as well and it builds up.

I go OVERBOARD on my heads in my cameras and clean every 20 or so hours but I don't expect to see 2000 head drum hours out of my cameras either...
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Old March 22nd, 2010, 12:45 AM   #10
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Erwin: I BELIEVE the information written to the tape is corrupt now, having been written to tape with clogged heads.
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Old March 22nd, 2010, 02:04 AM   #11
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Quote:
Originally Posted by Shaun Roemich View Post
Erwin: I BELIEVE the information written to the tape is corrupt now, having been written to tape with clogged heads.
90% of the time, in my experience, this is correct. The other 10% of the time, you clean the heads, recapture, and you're good to go.
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Old March 22nd, 2010, 02:56 AM   #12
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Well, I suggest you do the test...........

AFTER giving the heads a bloody good clean, hey, even three or four times if necessary.

If it's still happening, well, there's nothing for it but a professional clean, if you can find someone to do it.

If that doesn't fix it, there must be a hardware fault.

Thanks, Shaun, ain't seen it before, ever.

Couldn't reconcile what I saw with degraded head performance, under any circumstances.


CS
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Old March 22nd, 2010, 03:14 AM   #13
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Originally Posted by Chris Soucy View Post
AFTER giving the heads a bloody good clean, hey, even three or four times if necessary.
CS
Thanks for all your good comments...

How do I a bloody GOOD clean.... I have a cleaning tape. This is what I do...

- Put the camera in VCR mode (playback)
- Insert tape and play it for 10 seconds. Sometime I do this twice...
- END.

But I never do this in REC mode. Because the problem is with the recording and not with the playback.

How do I clean the RECORDING heads, or are they the same...
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Old March 22nd, 2010, 07:42 PM   #14
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Unlike the old VHS-based systems record and play use the same heads. Just play a cleaning tape per the instructions.
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Old March 23rd, 2010, 01:29 AM   #15
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Originally Posted by Don Palomaki View Post
Unlike the old VHS-based systems record and play use the same heads. Just play a cleaning tape per the instructions.
Thanks for the information...
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