Film-Tech Forum ARCHIVE: Colored/dark flashes at edit points in prints

This is topic Colored/dark flashes at edit points in prints 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=004022

Posted by Christopher Seo (Member # 7) on 09-22-2002, 02:41 PM:

While screening an original-negative print from an unnamed lab, I noticed colored or dark flashes in the lower half of the image whenever the film cut to a different shot. This kept occurring off and on during much of the print.

I then began to notice that the color of the flashes, if any, took on the tint of the incoming shot. I.e. an orange flash would immediately precede a warm, tungsten-lit shot, and a blue flash would precede a night shot.

Am I correct in supposing this has something to do with the color timing, and that the response of whatever light valve is controlling the printer lights may have some kind of overshoot? And is this particular to any sort of printing method, e.g. single negative as opposed to A/B rolling (not quite sure of the terminology)? I've noticed these kinds of flashes in regular release prints before, but usually they weren't too objectionable.

Posted by Josh Jones (Member # 447) on 09-22-2002, 06:04 PM:

Was your print scope or flat?

Josh

Posted by John Pytlak (Member # 331) on 09-22-2002, 10:07 PM:

Yes, the light valves/vanes on an additive printer change quickly, but not instantly. So there is usually a partial frame transition in the color balance as the vanes change from one setting to another.
http://www.acvl.org/manual.htm
http://www.kodak.com/US/en/motion/support/h1/printingP.shtml#plusminus
http://www.screensound.gov.au/glossary.nsf/Pages/Printers?OpenDocument
http://www.rtico.com/bhp/6131c.pdf

Cutting and printing the negative as A and B rolls (alternating scenes in two passes through the printer) can be used to "hide" these transitions and the splices in the negative.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Steve Kraus (Member # 476) on 09-22-2002, 10:38 PM:

Aren't changes usually incorporated into the IP or at least by the dupe negative stage so the release prints can fly through the printers one light?

Posted by Leo Enticknap (Member # 534) on 09-23-2002, 02:14 AM:

In the case of titles with a massive print run, I can't see how you could do it any other way. Faffing about with A and B rolls when you're making 2,000 prints with a week to do it in just can't be possible.

But for arthouse and rerelease titles where you're only doing two or three, I suppose they might still use A and B roll internegs, especially with colour films that have complex grading requirements.

Posted by John Pytlak (Member # 331) on 09-23-2002, 09:20 AM:

Yes, scene-to-scene color correction is usually finalized when making the answer print, and that color timing is used when making the master postive or IP, from which the duplicate negatives are made. The duplicate negatives used for release printing require little or no additional scene-to-scene correction.

Posted by Christopher Seo (Member # 7) on 09-25-2002, 10:12 PM:

Thanks for the info, guys. The print was Scope but this goes way beyond the negative splice flashes I have seen, seeming to fill about half the frame. And I guess if this sort of problem is deemed acceptable for an EK print, it is probably considered OK for the IP/IN used in release printing as well.