Film-Tech Forum ARCHIVE: More unidentified scratches

This is topic More unidentified scratches in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Ken Lackner (Member # 1002) on 10-30-2001, 11:47 AM:

I know the topic of unidentified scratches has been beaten to death on this forum, but I have another one for you.

I was watching the end credits of From Hell, and on the left side of the screen I noticed that every few seconds a bunch of white dots (I know scratches are not usually white; it may have been light yellow, but it looked white) would flash on the screen, and it seemed that they were moving up the screen. Any clues as to what this is? Thanks.

BTW, our equipment consists of Teco platters, Kinoton FP23C projector, and CE FM-35 failsafe.

Posted by John Pytlak (Member # 331) on 10-30-2001, 12:03 PM:

"White" dirt or scratches are usually on a negative image element, and are called "shadow image" because the cast a shadow in the printing light, leaving an unexposed lighter spot on the print. Your observation that they repeat on a regular basis, and appear to move up the image along the left hand side, makes me suspect that the printing negative somehow was damaged by a "roller repeat" mark.

What is the exact measured distance between the spots as they appear on the print? Is there any evidence the damage occured to the print itself, such as a physical scratch or dig to the emulsion surface? Any chance it is just a digital "glitch" from the CGI titles (i.e., does it move upward with the title crawl?)

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Ken Lackner (Member # 1002) on 10-30-2001, 12:18 PM:

As far as I can remember, the dots do not crawl up the screen with the titles. The dots just seem to flash randomly across the left side of the screen and move up the screen. I will pay close attention to it tonight when I am at work. Do you want the measured distance between specs on the actual film?

So it sounds to me like you're saying this is dirt that was on the negative and got transferred to the print? If so, would the studio replace the reel at no charge?

Posted by John Pytlak (Member # 331) on 10-30-2001, 12:47 PM:

Measure the actual distance between the specks on the print itself. The distance is the circumference of the roller that caused the damage.

Without actually seeing the print, I can only speculate as to the cause. I assume you are showing the correct image area as defined by standard SMPTE 195 and measured with the SMPTE 35-PA (RP 40) projector alignment film? If you are showing too much of the left hand side of the image, you may be seeing areas of the analog and DTS soundtrack that are well outside the area normally projected. But if objectionable amounts of shadow image dirt intrude into the normal picture area, the fault does not lie with the theatre.

Posted by Dustin Mitchell (Member # 372) on 10-30-2001, 03:56 PM:

We have had this problem also, though on the right hand side of the screen, everything else is exaclty like our problem though. I imagine the orientation of the film-soundtrack to the wall or not-makes the difference. The problem here was the film was slipping out of the magazine rollers (ones above and below projector that feed from and to the platter). The film would ride on the edge of the roller and make thes "dots" as they sometimes appear. Sometimes a less than qualified operator would lazily load the film with it not riding on the roller properly, but other times the film would simply slip out of the roller. Check your roller alignment. If you can't re-align your rollers to solve the problem, you might want to order rollers with deeper flanges to keep the film in them securely.

Could you get a picture of your current roller setup?

Posted by John Pytlak (Member # 331) on 10-30-2001, 04:08 PM:

If your equipment is causing the white marks, the film will actually have physical impressions or scratches, easily visible by viewing the surface of the film by oblique specular lighting (view the film surface with a spotlight or in the projector's light beam). "Shadow Image" dirt or scratches do not leave a physical impression or scratch on the print.

Posted by Ken Lackner (Member # 1002) on 10-30-2001, 04:10 PM:

I don't have a camera, so I won't be able to take pictures. I'll check out both suggestions when I'm at work tonight.

Posted by Ken Lackner (Member # 1002) on 10-31-2001, 12:52 PM:

Well, I could not see the individual spots on the film, but half of the image area as abraded. One of the rollers had a really bad flat spot. I am going to try to take a picture of it and post it here. (BTW, I changed that roller!)

Posted by John Pytlak (Member # 331) on 10-31-2001, 01:06 PM:

It is unusual for abrasion of the print to show up as white spots, but it can happen if all the emulsion is picked away by the abrasion.
Base side scratches usually show as black. Emulsion side scratches show as black, green, yellow or white, in increasing order of severity:

Here's a link to an article on "Scratch Free Presentations":
Scratch-Free Presentations

I find holding the film in the light of a spotlight or in the projector beam really shows up any scratches and abrasion your equipment may be causing.

Posted by Gordon McLeod (Member # 33) on 10-31-2001, 01:10 PM:

Would not a print emulsion scratch even if white have a coloured fringe since it would be very difficult to remove the emulsion in a perfectly perpendicular fashion

Posted by John Pytlak (Member # 331) on 10-31-2001, 03:09 PM:

Yes Gordon. As I said, a pure white mark caused by an abrasion or dig on a print would be very unlikely. Maybe a "pinprick" type of emulsion dig would appear to be white, but most others will have color.

Posted by Ken Lackner (Member # 1002) on 11-01-2001, 12:17 AM:

So I could be dealing with the negative dirt along with some *slight* abrasion from my roller? The abrasion that I could see when I held the film at an angle under the light did not appear to match the pattern of specs that I saw on screen, so my guess is that the two are unrelated.

Posted by John Pytlak (Member # 331) on 11-01-2001, 08:46 AM:

The key question is whether the white spots you are seeing are part of the image that was printed, or are the result of a dig or abrasion to your print. Also, whether they are occuring within the projectable image area defined by standard SMPTE 195. If you have a hard time finding them on the print, you may be the only person taking notice of them.