This is topic Focus Problem-I'm Baffled! in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Thomas Ferreira (Member # 96) on 08-21-1999, 11:25 PM:
I've never run across this in all my years in the booth, and I'm sure there's a logical explanation, but I can't find it.
I made up my print of Mickey Blue Eyes Thursday night off of the 6000' reels. My house light cue is on the soundtrack side, and I did apply it carefully, making sure not to overlap the perfs. I didn't have time to screen the print, and noticed when the first matinee ran through on Friday that the end credits were badly out of focus. Other perodic checks of the film had revealed no problems. The film is flat, and I have a good sharp flat picture in that auditorium, so I figured that maybe R6 was bad and needed to be replaced. I watched the last ten minutes of the next showing, and the focus is sharp and clear, right through "The The End". When the film is cued and the house lights go up, the credits are out of focus.
OK, so I figure I wasn't as careful as I thought and my cue is bad, so I pull off the end of the print to check the cue. Seems OK, but I put on a new piece of cue tape anyway. Same problem.
Assuming that it is the cue tape that's causing this, why would it go out of focus? The projector is a V9 with good tension on the gate. I should know why this is happening, but I'm coming up stupid. ------------------
Posted by Brad Miller (Member # 2) on 08-21-1999, 11:52 PM:
Your problem has to do with heat from the lamp. I have noticed this only on Kodak Vision prints. I am assuming this is a Vision print...you can tell by the code #2383 printed on the edge of the film in the SDDS soundtrack. This does not seem to be problem with Vision Premiere (code #2393) or Fuji prints. I am also assuming (I have not seen the film) that the end credits are over a black background.Black film absorbes more IR heat from the xenon and in turn will emboss and burn quicker than clear film or film with typical images on it. This is why it happens as soon as everything goes to black...the film is suddenly absorbing too much IR heat.
General running of the print will smooth it out over time, but it may take a week or so. You can try loosening the closure in the gate so there is a little bit less tension, but don't expect too much. The quickest way to solve your problem is to lower the power output of the xenon, but your picture will suffer greatly with that solution. Ideally, get yourself a bottle of FilmGuard. Using FilmGuard on prints will raise the tolerable heat level since the print would at that point be wet...and allows you to use more intense lamps without fear of blistering. 
I've run Super8mm prints with a 2000watt lamphouse and FilmGuard with no damage whatsoever.
Yes, another shameless plug...but I'm not joking. A film running exactly as described above will run perfect with FilmGuard. Unfortunately, you've got 2 more weeks to wait. 
Posted by RICK HAMILTON (Member # 115) on 08-21-1999, 11:59 PM:
If it is just the credits then my guess would be that after the film was done the director got pissed at someone, probably a tech, and they had to redo the credits with this guys name missing. Luckily this tech had a good friend in the focusing department who made things right!!!
Posted by RICK HAMILTON (Member # 115) on 08-22-1999, 12:00 AM:
Either that or that film-guard guy is right!
Posted by Gordon McLeod (Member # 33) on 08-22-1999, 10:56 AM:
A easy way to test the cue foil might be at fault is to manually run the print with the foil removed and see if the problem persits
If it does then look to a gate related problem (shakeamecanica has lots of those)
If it is heat releated check thatthe blower on the back of the machine is working okay and that the air filter is clean
What make of lamphouse (does it have a heat filter or a cold mirror) and what size of bulb
Posted by Thomas Ferreira (Member # 96) on 08-22-1999, 10:06 PM:
It's a Christy lamphouse with a mirror and a 1600 W bulb. By the way, the credits are not over a black background, and I did notice that it goes back into focus during the rating. Totally bizarre.
Posted by Rick Long (Member # 213) on 08-23-1999, 12:46 AM:
Here's a long shot. Cinemeccanica projectors had a problem with their 0080 latteral-guide rollers (located directly above the gate). They sometimes stick open. The problem is easily resolved with WD-40
(be sure to protect the back element of the lenses). Just push the roller open and spray a couple of quick squirts. Work it back and forth until it operates freely. If your gate is one of the newer types with the "pusher pads", check these for sticking in the same manner. Why this only does this with the arrival of the cue is anybody's guess.
Posted by John Pytlak (Member # 331) on 08-23-1999, 09:32 AM:
Brad Miller is correct that the closing credits are most prone to "focus flutter" because they are often white letters against a black background, which absorbs the most radiant energy. Kodak Vision Premier Film 2393 actually has a higher density and slightly thicker emulsion than Kodak Vision Print Film 2383. Some pictures (e.g., "Seven", "Evita", "Saving Private Ryan", etc.) are processed with a special process that deliberately leaves silver in the image area of the film to increase the contrast and reduce color saturation --- this silver will absorb more infrared energy, aggravating heat-related problems with large lamphouses. Gordon McLeod is correct in advising a check of proper lamphouse alignment and heat filtration.Another possibility is that the tail end of the last reel was originally wound on a small diameter core, giving it "core-set", which will affect focus until the film relaxes. Many times the final reel is the last one processed (credits are often up in the air until the last minute), so it may have a higher moisture content than the other reels, which can also affect focus until the print dries out.
------------------
John Pytlak
Posted by Brad Miller (Member # 2) on 08-23-1999, 02:16 PM:
Gotta agree with John on that one. He is 100% right about the last few minutes of film on the platter. Personally, I ALWAYS add 50 feet of tail leader in addition to whatever comes on the last reel to EVERY print. This pretty much solves that problem, and protects the tail end of the movie, including keeping that rating band in pristine condition!Still, I think it is a definite problem with the heat from the lamp. If you were planning on getting a bottle of FilmGuard anyway, use it on that print and the problem will go away on the first pass.