Awful tape problem w/Canon-shot tapes-- MacDV Digest #2197

[Ted Langdell]

Hi, Richard, 

As an XL-1 owner, I've had problems very similar to the ones you describe.
It's got me to clean the heads fairly regularly, and to CHECK THE TAPE in
the VCR mode, to see how well it plays back.

That's alerted me to problems when a reshoot was possible after cleaning.
You won't see the problem in record-search, or when you're in fast forward
or rewind holding the button down to see a viewable picture.

Sometimes it can be as bad as you describe, or worse... totally gone. Other
times, just blocky along the right hand edge of the picture.  The problem is
usually accompanied by time code that hangs, and then catches up, then
hangs, etc.

I've had some success in playing "iffy" tapes back on a Sony TRV-7
single-chip camcorder, when even the Canon that shot it, and a series of
decks ranging from the little DVCAM deck with an LCD screen to a DSR-30 and
DSR 80 wouldn't work.  The more expensive the deck, the worse it got.  Can't
explain why the TRV-7 worked when others didn't.

A friend had similar issues with stuff he shot with a VX-1000.  After moving
it from deck to deck, he finally hit a winning combination and dubbed it.

IF the head(s) clogged during record, there may not be much that you can do.
It's recorded that way.

You might try cleaning the heads of the deck you're playing it in before
playing the tape(s) back and see if that helps.

You might also try running the tapes in fast forward and rewind to see if
that makes a difference. If the tapes are shedding particles (which clog the
heads), but have a recoverable signal, it might knock off enough stuff to
enable making a firewire dub.

This is "burnishing" the tape, a process that was standard operating
procedure in the days of 2" quad tape and often with 1" to get any loose
particles of oxide taken care of before actually recording on it. One
wouldn't want to lose the network program due to a head clog... eh?

I wonder if the cause of the problem has anything to do with the lubrication
type used on the tape.  Some are "wet," others "dry."  I've read threads in
other fora where that's been an issue.

I know that Panasonic says to not use anything other than a specific tape in
its new 24p VX-100 because of the issue.

Hope some of this helps.

Ted.

Let us know what happens.



> From: "Macintosh Digital Video List" <MacDV at lists.themacintoshguy.com>
> Date: Tue, 27 May 2003 21:45:16 -0700
> To: "Macintosh Digital Video List" <MacDV at lists.themacintoshguy.com>
> Subject: MacDV Digest #2197
> 
> Date: Tue, 27 May 2003 18:52:53 -0700
> Subject: [MacDV] Canon XL1 Nightmare
> From: Richard Brown <richard at go2rba.com>
> Message-Id: <18664048-90AF-11D7-B6AB-000393B3BF58 at go2rba.com>
> 
> Hello all,
> 
> I have a uniquely terrible problem which has arrived at my facility.
> About 50 Mini DV tapes representing 3 years of preproduction, and 3
> months of shooting, of a Canon XL1 shot feature film production.
> 
> Now, the problems...
> 
> 1) Massive audio dropouts, up to a full tape at a time. The "spikes" of
> audio which are audible are on the order of milliseconds, not long
> enough to hear a single word.
> 
> 2) Mosaic video dropouts, visually looking to be keyed to motion,
> either of camera or of talent. This can be merely a sprinkling of non
> regular groups of pixels or huge amounts of mosaic noise, again, keyed
> apparently to any form of motion. It defies the "dirty head" issue as
> on the same tape, there may be a section which is fine, with bad in
> front and behind it.
> 
> 3) The problem increases continuously over time from the beginning of
> the shoot to the end of the shoot. The latter tapes seem wholly
> unusable, with the earliest tapes showing fewer problems, but not
> without problems.  Still, dirty heads make more sense in that the last
> tapes are essentially full time bad. The video NEVER goes out, simply
> the mosaic distortion mounts.
> 
> This is the second time I've encountered nightmarishly bad video/audio
> from the XL1, the first time being a network show which ran by in the
> middle of the night for us to check out a bad XL1 tape (they couldn't
> read it, and neither could I, but the actual XL1 which shot the tape
> played the same tape back fine.)
> 
> Some of the early footage utilizing the on-camera mic shows good video
> and audio (NOT ALL, I've seen plenty of bad on-camera mic as well), but
> I hear from the director there was an outboard mixer with a pro shotgun
> mic for many of the scenes which fall apart... Thus I wonder about
> XL1's with Hi-Z / Low-Z mismatches as well on how, in this situation,
> they misbehave.  Suggesting there was no impedance mismatch, work tapes
> in VHS were struck at the time of shooting from the XL1 outputs
> featuring good video and audio.
> 
> Also, the film was lit with HMI.
> 
> So my questions:
> 
> Anyone had these problems and fixed them? From the network issue, I
> understand XL1's can get finicky, only able to play back their own
> tapes (and vice-versa) when in odd calibration. Is there a work-around?
> "Digital tracking?" -- which is to say both XL1's and Sony PD150's are
> nothing but a mess of tiny analog trim pots under their covers.
> 
> Will audio impedance problems destroy video and audio as recorded but
> output normally through the video and audio outs on the XL1?
> 
> Will HMI ballasts and their frequencies destroy XL1 shooting?
> 
> Compounding our problem, the pro shooter with the XL1 in question just
> sent it for full maintenance, thus ending possibility of running the
> tapes through the shooting camera, UNLESS Canon allows the camera to
> stay in its state of  mis-calibration, assuming it would otherwise deny
> playback of existing tapes.
> 
> Stuck between a huge rock and an expansive, EXPENSIVE hard place...
> S.O.S.!
> 
> 
> Richard Brown
>