Queer problem:

Filming local church concert. Overhead mics attached to Canon XM2 via mixer unit and Canon XLR adapter. Camera controlled remotely via LANC.

I filmed a rehearsal to check levels etc. no problems - played back tape - happy with sound and picture quality.

I filmed the concert the day after using the same set up. Changed tapes at the interval. During recording the camcorder tv screen was displaying normal picture and sound levels.

Now here is the problem:-

When playing back tape one there is a period of 4 minutes or so of black screen - no sound. Then the a picture appears broken by a series of black bands together with sound distortion. After a while the picture and sound reverts to normal. I have now lost the first two acts.

When playing back tape two the same picture and sound distortion occurs for a period of around five minutes then reverts, again, to normal.

I was using re-used Sony Premium 60 mini DV tapes. One of which I used to tape the rehearsal. Both tapes had been recorded over (lens cap on) prior to the concert to clear the tapes - both ran to the end and were then rewound - retensioning the tape.

I don't think the camera was affected by the mic connections or was being affected in any way by the mixer as I would assume that I would have noted that after I filmed the rehearsal and any interference would have been constant.

My initial thoughts were that it may be the LANC sending out spurious messages but not convinced as these would have interrupted the record mode which would, I guess, have manifested itself on the monitor screen. I was watching the screen the whole time virtually and everything seemed normal.

I tested the LANC and camera the following morning and the camera recorded perfectly well. Could be the start of an intermittent camera fault I guess but my gut reaction that it is more fundemental than that.

Having retensioned the tapes and I am wondering whether by doing so it may have caused the tapes not to travel over the recording heads properly during the first few minutes until the tapes had settled down to 'normality'. The variations of tension though would, I guess, have been so miniscule that I can't really get my head round that theory.

Has anyone come across this type of problem before? I need to get to the bottom of the problem as I film this type of event regularly and the last thing I want is a recurrence of the problem.

Help

It could be the tapes or the recording head could be dirty. When was the last time you ran a head cleaner though it? Dose it do it on other tapes? When I record something important I always use a new tape, after all there only $5.

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Wil Chapman Jr.
Oly, Washington
DP, Producer, Editor

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Tape heads were cleaned recently. Tried another used tape (not retensioned) no problem. I will use new tapes in future and test before I start to record in earnest. Not knowing whattthe problem was (is) makes it difficult to guard against it in future - clearly keep fingers crossed scenario and hope it was a one off

I have never reused tapes as they are generally very cheap to buy. Also, I have never tensioned or retensioned tapes or recorded black onto them. The only problems I've encountered are ones involving dirty heads but a quick run through with a tapehead cleaner clears it. I just leave about 30 seconds of blank tape at the start and record up to about 59 minutes and stop there and thankfully I've been trouble free.

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