Film-Tech Forum ARCHIVE: ill-centered hard mattes on old film?

This is topic ill-centered hard mattes on old film? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=005553

Posted by Carl Martin (Member # 1146) on 11-18-2003, 06:08 AM:

we're showing a film 1.66 on one screen, with the framing set perfectly. the trailers before the film are hard-matted somewhere between 1.66 and 1.85, and the image between the mattes is centered vertically on the screen. so far so good. but the other day we ran a feature-length show of mostly 80's trailers and damned if they weren't all high on the screen. those with hard mattes would show a black bar at the bottom and the image would reach the top of the screen and probably beyond. no, it wasn't a mis-thread. i don't do that, and it wasn't off by as much as 1/4 frame. i wouldn't have thought that framing specs were different 20 years ago. the most plausible thing i can think of is film shrinkage lowering the image in the gate and raising it on screen. but i'm still surprised at the consistency from trailer to trailer. on the other hand, they have all been stored on the same 6k's for most of their lives.

carl

Posted by Steve Guttag (Member # 268) on 11-18-2003, 06:36 AM:

Carl,

You have two potential issues...they were printed wrong (I've shown many a mis-racked film)...the second involves bi-directional printing...if your trailers were on the reverse print direction then you will be off by difference between the sprocket tooth and the perforation height on the printer.

Nothing beats when they make a two-strip 3D film with bi-directional printing...yep seen that happen too...every reel seems mis registered (left to right eye).

Steve

Posted by Steve Kraus (Member # 476) on 11-18-2003, 08:48 PM:

the second involves bi-directional printing...if your trailers were on the reverse print direction then you will be off by difference between the sprocket tooth and the perforation height on the printer.

That dog won't hunt. The shift you would get by reversing continuous contact printing will only be the difference in sprocket hole height caused by BH vs. KS, short pitch vs. long pitch etc. which is a much smaller shift than that described. If you have a sprocket handy you can try it with a couple of layers of film bi-packed. Or you can simulate with a couple layers of film and some sort of pin pushing one way or the other. With two layers of the same type of film the alignment remains the same!

Ditto step contact printing. Maybe with an optical printer if no other adjustments are made but that's unlikely the cause.

Posted by Dominic Case (Member # 1830) on 11-19-2003, 12:18 AM:

quote:
the second involves bi-directional printing...if your trailers were on the reverse print direction

A mis-adjusted printer can conceivably cause this: much less than 1/4 frame, possibly up to half a perf-height - but if you have a collection of trailers joined together then it seems very very unlikely that they would all have been printed the same.

You would need to examine the print itself to determine if the framing is off-centre relative to the perfs, or if for some reason the other material that you have aligned to is wrong.

Posted by John Pytlak (Member # 331) on 11-19-2003, 01:11 AM:

I agree with Dominic that bi-directional printing would not explain a difference that big. Likewise, shrinkage would not explain it, as enough shrinkage to notice would make the film suffer sprocket damage. As he suggests, examine the print itself, and try to accurately measure the actual shift in the center of the frameline from the nominal of exactly between two perfs.

Posted by Frank Angel (Member # 248) on 11-19-2003, 07:33 AM:

Are you saying that ALL the trailers of a particular age are misaligned and by the same amount? Or does each one have an offset error different relative to each other? If you mix and splice a few trailers together, does the matte jump to different positions for each one? If that is the scenario, then yes, you may have a few trailers that are just badly printed.

I can understand one or two having a off-center matte -- I've seen that, but really only on very rare occasions (and it had nothing to do with the age of the trailer -- it can happen to new as well as old) but the likelyhood that you could find 2 or 3 trailers where they ALL are printed incorrectly to same error amount, i.e., the matte is shifted up or down to exactly the same position in each trailer is so unlikely that it points to some other factor rather than printer error.

If you told me you had a reel where trailers 1 and 2 are in perfect frame and then 3 , 4 and 5 are all out by the same amount, but not enough for it to be a misframe, I would say look to the framing assembly -- perhaps something has caused it to slip slightly, say a really bad splice -- that would cause everything after that splice to slightly out.

I had gears strip once while the film was running and what happened on the screen was at first the frame moved up slightly is small incriments. Of course that was a catastrophic failure, but maybe there is something less severe causing the frame assembly to slip by a small amount.

That;s only a guess....the guys with more mechanical saavy can tell you if that is a possibility.

Frank

Posted by Carl Martin (Member # 1146) on 11-20-2003, 05:08 AM:

the regularly scheduled program run before and after the trailer show was framed perfectly, so there was no framing drift. the offset on the trailers seemed quite consistent, but it's hard to judge given that the mattes vary in size and not all the trailers have them.

in any case, i had to un-platter the trailers to make room for another film, so i'll have to put the issue to rest for the time being.

carl