With Half-Sized Frame and SP/LP error, am I getting lower quality?

Question

Seven years ago, I recorded some videos with my Canon ZR miniDV camcorder.  I want to preserve the quality of these videos by archiving them on my Mac.  The read head on this camcorder is broken. So, I'm borrowing my brother's Sony Digital Handycam DCR-PC110 NTSC to play these miniDV video tapes.
When I use iMovie 6 to import, I get this message:
"The camera is sending half-sized frames, which iMovie can’t accept. Check your camera’s record mode (this is the setting that affects recording quality, which determines the total recording time on a tape). The mode must be set to “SP” or “LP.” If that doesn't help, try removing all the cables and batteries from the camera, wait a minute, replace them, and then reset the date, time, and record mode."
The recording mode is already set to "SP". However, I still cannot import. Every time I try to play the video, it shows a fraction of a second of the video and then it stops. If I disconnect the camera from the Mac, I can play the video without a problem. It seems that iMovie 6 will not allow me to play this video.
Does anybody know what the problem is?
With my brother's miniDV tapes, I don't get this problem on his Sony Digital Handycam.
From some research, I read that it might have something to do with playing a PAL recording instead of NTSC.  However, my cameras are NTSC.  I've never (consciously or remember to) use PAL.  iMovie 6 is set to 29.97 bps frame rate, which is supposedly NTSC.
I tried the suggestion from this posting:
https://discussions.apple.com/message/1808010#1808010
Which is:
-  I disconnected the camera from the Mac.
-  Started up iMovie 6.
-  Started playing my miniDV tape.
-  Connected the firewire from the camera to the Mac
Now, I can play and import the miniDV video on iMovie 6.  However, I'm curious as to whether iMovie is inputting NTSC and saving into PAL, or vice versa.  Therefore, I'm concerned about the possibility of losing quality.  Would anybody know if I will be losing quality?

Answer 1

"..the last 43 minutes of clips, cannot play well on my Canon camcorder.."
Run through the tapes to see how many total minutes of material you have on these tapes. A miniDV tape records a maximum of 63 mins at Standard Play rate, and up to about 90 mins at LP (Long Play) rate.
If you have more than 63 mins of material on these tapes, then the recording was made at LP rate.
At LP rate, the tape moves at 2/3 the speed of SP, which means that the video tracks recorded on the tape are very narrow. This means that when those tapes are played in a different camcorder the heads may read the tape properly, because there's no margin for error on these very narrow tracks. When replaying an LP tape, the camcorder's heads may not properly align with the recorded track, giving the 'half frame' error you mentioned.
No camera manufacturer guarantees that any LP material will play correctly on any camcorder other than the one on which it was recorded (because of these narrow LP tracks). [Sony created the professional 'DVCAM' speed - one-and-a-half-times normal SP speed, so two-thirds the recording time - to provide -w-i-d-e-r- tracks than normal, and thus ensure that professional DV recordings can be played back and edited on equipment other than the camcorder which was used
for shooting the material.]
The only solution for LP tapes is to try importing from as many different camcorders as possible till you find one which will do the job. (I had to do exactly the same thing last week, and found that various other Sony 'consumer-grade' camcorders - the material was recorded on a Sony - couldn't 'lock onto' the LP track, but professional or 'prosumer' (more expensive) Canon (XLH1) and Sony (FX1) camcorders could play the old LP material.)
Before trying to play old tapes, whether SP or LP, always wind them fast-forward all the way to the end, then rewind them - at least once - to make sure that the tape layers don't stick together, and to ease the stresses in the tape. You should also do this once a year to every recorded tape, to avoid stresses, pinching, and 'print-through' (seepage of magnetism from one layer of tape to others).
P.S: Have you tried cleaning the 'broken' head on your old Canon? Dip a cotton bud in methylated spirits - or, better still, carbon tetrachloride 'dry cleaning' fluid - and slowly turn the head drum, and wipe up and down it, over and over again ..making sure NOT to catch cotton wool in the sharp narrow gap between each of the (two) heads, which are each halfway round the head (at 180 degrees to each other). Wipe carefully, then examine the cotton bud and see if there are any brown stains on it ..if so, you've cleaned old muck off the head. Repeat with a new cotton bud until there are no more stains on it. Leave the head drum to dry for 10 minutes, playing gentle (half) heat from a hair-dryer on it, but don't melt the plastic camcorder - so that the fluid evaporates and doesn't stick any tape to the head! - then try importing again.
P.P.S: "..It seems that iMovie 6 will not allow me to play this video.." iMovie's tolerance for damaged digital video frames is far tighter than any camcorder's: a camcorder will often replace 'damaged' frames with detail from the undamaged frame before, so doesn't give a clear idea of how damaged the video data may be. If it won't import, it's damaged, possibly through head misalignment, or through a weak or dissipated signal. (Earlier versions, such as iMovie 2.1.2, were more tolerant of 'dodgy' video, and could import material which later versions, e.g; iMHD6, won't allow accept.)