Film-Tech Forum ARCHIVE: Emulsion on wrong side of film?

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Posted by Michael Barry (Member # 237) on 06-01-2000, 10:25 AM:

I inspected a black and white five spool feature the other day (no, not 'Manhattan'! It's a Croatian feature from 1981 called 'Rhythm of Crime') and I encountered something extremely odd when winding through spool 2.

I was checking for correct placement of changeover cues (Hi, Steve G!) - I was at the tail end of the reel winding back to the head, from left to right with the soundtrack side facing away from me, and there were the cues opposite the soundtrack (on my side) where they should be. In a nutshell, I was rewinding the reel, emulsion in.

Then, I realised that the emulsion was facing up! Since the leaders were poor and did not identify head/tail orientation clearly, my first reaction was that someone had mistakenly cue-marked the head of this reel. But no, because the image-orientation and subtitle printing were the right way around.

So I rewound the spool, and threaded the projector (after hours) for the first time ever(!) with the emulsion facing the lens and the base side facing the lamp just to make sure I wasn't crazy. It worked, with the subtitles right there in um...black and white. The image was a little soft, however.

The rest of the feature's spools were printed conventionally. So what is this all about, and has anyone ever seen this before?

Posted by Gordon McLeod (Member # 33) on 06-01-2000, 10:32 AM:

That reel is a dupe copy

Posted by John Pytlak (Member # 331) on 06-01-2000, 10:50 AM:

Standard SMPTE 194 "Motion-Picture Film (35-mm) ---Projector Usage --- Release Prints Having Four Perforations per Frame" says:

"2.1 The photographic emulsion shall be on the side of the film which faces away from the projector lens."

In other words, in a 35 mm release print, the image should read correctly when viewing the film through the emulsion side. This orientation would normally be achieved when contact printing an original negative (or a duplicate negative) onto print film with emulsion-to-emulsion contact. Negative film is exposed with the emulsion toward the camera lens, so the image reads correctly through the base side of a negative film, and a contact print is a "mirror image" of it.

The reel 2 you had was evidently printed with the wrong orientation. In a contact printer, this could be done by printing with the base side of the negative in contact with the emulsion side of the print stock. Printing through the base would also explain why the image "was a little soft".

BTW, the normal orientation for 16 mm prints is with the emulsion facing the projector lens. This is because 16 mm grew from an amateur format where reversal camera originals were usually projected, rather than contact prints. Today, 16 mm prints may have either orientation, requiring slight refocusing of the lens and sound optics for optimum results.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

Posted by Bruce McGee (Member # 131) on 06-01-2000, 11:52 AM:

I was wondering when and if I might run into something in 35 that was emulsion IN.

Back in my old TV days, we would get stuff now and then with reversed emulsion in 16.

The station would get calls complaining about soft focus.

Instead of calling MCR, they'd call me. All I would do is adjust focus on the TP-6, and 66.

The engineers always said that they thought the film was just soft.

I never got any dupes for broadcast.

Posted by John Pytlak (Member # 331) on 06-01-2000, 12:09 PM:

Bruce:

As I noted, the preferred orientation for 16 mm should be emulsion toward the lens (like a reversal camera original), but prints with the opposite orientation are not uncommon. As you know, some of the Kodak projectors (EASTMAN Model 25, EASTMAN Model 30, KODAK Pageant) allowed refocusing the sound reader for optimum frequency response.

The STANDARD (SMPTE 194) orientation for 35 mm prints is with the emulsion side facing AWAY from the projector lens. The image will read correctly through the emulsion side. There should be no exceptions.

Winding orientation on a core or reel is a different, but related, issue.

Posted by Scott Norwood (Member # 30) on 06-01-2000, 01:15 PM:

Can o' worms alert!

Oh, no! We're now doomed to a month of "emulsion in/emulsion out" and "soundtrack up/soundtrack down" threads! Which will, of course, lead to many more months of "platters vs. changeovers," "THX vs. HPS-4000," etc.

Posted by Brad Miller (Member # 2) on 06-01-2000, 02:07 PM:

I've got a better idea. Click on "search" above and perform one each of the following.

Try:
*emulsion
*soudtrack
for the emulsion in/out winding orientation

*HPS
*THX
for sound discussions

*platters
*changeovers
*or you can simply search for username "Steve Guttag"
for pros and cons on film transport.

Posted by John Pytlak (Member # 331) on 06-01-2000, 02:13 PM:

Scott:

No controversy.

Although SMPTE Recommended Practice RP39 specifies emulsion-in winding for optimum focus performance, it is based on Kodak tests with TRIACETATE prints on reels having small hubs. There is not enough data to specify the optimum winding orientation for polyester prints, and with the large hub diameter used on platters, the focus performance shouldn't vary too much with winding orientation anyway.

Recent experience does show some correlation of winding orientation with sensitivity to "static cling", since the natural "curl" of the film affects how easily the film can "pull in" with a slight static attraction. My article "Platter Patter" in the September 1999 issue of "Film Notes for Reel People" recommends "on a platter, use the orientation that gives the best winding and pay-out", which may vary with humidity.
http://www.kodak.com/US/en/motion/newsletters/reel/september99/pointers.shtml

Regarding the issue of scratching the print by having it rub on the surface of the platter, many feel that the analog soundtrack should be up, to protect it from abrasion. But others can argue that abrading the right hand side of the picture would just as serious. The best solution to this problem is to position the guide rollers carefully so as not to abrade the film in the first place.

Posted by Gordon McLeod (Member # 33) on 06-01-2000, 02:45 PM:

For many years we had several 2 projector 70mm 3d systems running here at Ontario Place and by the nature of 3d photography one eye image is printed with the emulsion towards the lens the other eye is emulsion towards the lamp
To help prevent operator error we had all reels wound to run off the front of the reels (emulsion in) All were non stripped polyester prints and the right eyes that were wound emulsion out all had focus drift problems in the course of the 20 min reel (6.5K lamps) with no focus drift on the emulsion in right eye print

Posted by John Pytlak (Member # 331) on 06-01-2000, 02:53 PM:

Gordon:

Were they triacetate prints? Again, SMPTE RP39 says emulsion-in should give better focus stability, especially on small hubbed reels.

Posted by Gordon McLeod (Member # 33) on 06-01-2000, 03:15 PM:

Polyestar prints right wound emulsion out unstable focus left eye emulsion in stable focus
8" hubbed reels

Posted by John Wilson (Member # 269) on 06-01-2000, 09:28 PM:

Our IMAX 3D prints are now emulsion toward the lens for both left and right eye versions. With a 15k lamp, this plays havoc on the field lens causing a 'smear' (best way to describe it) as the wiper bars pass over the field lens which looks quite blah on screen.

Dropping back the focus of the lamps will allow these to be run with less directed heat and thus without smearing.

2D is still emulsion away from the lens and thus, no smearing no matter how high the intensity of the lamp.

Posted by John Pytlak (Member # 331) on 06-02-2000, 06:26 AM:

John:
The heat of the 15K xenon lamp and/or the hot field lens is evidently driving moisture or some other contaminant out of the gelatin emulsion, which builds up on the field lens. Have you sent in samples of the "smear" material for analysis by Kodak via IMAX or DKP70mm? We can use HPLC or atomic absorption analysis to analyze even tiny amounts of material to identify the origin.

Posted by John Pytlak (Member # 331) on 06-02-2000, 06:51 AM:

Gordon:
Your experience says the emulsion-in winding specified by SMPTE RP39 is also valid for polyester prints on reels.

As noted before, for platters using a large hub where "core set" is not as much of an issue, use the winding orientation that gives the best pay-out performance and wind quality on the platter. Since film curl varies with relative humidity, the best winding orientation on a platter may be different in very dry conditions than in humid conditions.

Posted by John Wilson (Member # 269) on 06-02-2000, 07:38 PM:

John:

Yep...sample sent to Kodak (James J Delabarto) a little over 6 months ago on a field lens he arranged to be sent here for that purpose. I e-mailed him only recently (less than a week ago, actually) to see if he ever found out anything on it.

Apparently, there's another 18k setup in Florida which has the same problem.

Is there any real reason why 3D prints cannot be printed with the same emulsion side as 2D?

It would solve a serious problem very quickly as our 2d suffers now not only from the high gain screen, but also from lower light than necessary to compensate for the smear.

Thanks

------------------
"I heard a voice behind me say...'Reach for it, Mister'... I spun around...found myself face to face...with a six year old kid! Well I just threw my guns down, walked away... LITTLE BASTARD SHOT ME IN THE ASS!"

Gene Wilder - Blazing Saddles

Posted by John Pytlak (Member # 331) on 06-05-2000, 02:24 PM:

John Wilson:

I talked to Jim Delabarto about the "smeared" field lens you sent via IMAX. Jim said he responded to you and IMAX by e-mail several months ago, with the analysis of the material. The "smear" material was analyzed as a plasticizer that is used in the manufacture of polyurethane rollers. The gelatin film emulsion evidently picks up minute amount of this material, and the very high radiant energy and hot field lens drive it out of the film so it deposits on the field lens. This has only been reported when using the very large lamps.

As you know, one or both "eyes" of 3D films are shot with a mirror in the optical path of the camera, "flipping" the image orientation, whereas 2D films are shot with the negative emulsion toward the lens. So a 2D contact print will "read" correctly through the emulsion, and project with the emulsion toward the lamp (rotor). A 3D print will have the opposite orientation because the negative was exposed through a mirror. The only way to correct this would be an extra optical duplicating step or printing through the base, both of which reduce sharpness.