Film-Tech Forum ARCHIVE: Uneven Focus On The Screen

This is topic Uneven Focus On The Screen in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Patrick Matthews (Member # 2705) on 12-07-2006, 02:52 PM:

Greetings,

We are running two PRO 35's at our theatre, one of which runs as good as it can, the other is having some problems. I been having problems getting focus on our right machine even. I see this mostly with scope films but I notice it on flat too. I have tried adjusting the various gate tension adjustments but that just seems to move the out of focus are around the screen. Anyone have any ideas as to why it would be doing this?

Posted by Gordon McLeod (Member # 33) on 12-07-2006, 04:01 PM:

Probably the rails need to be replaced Also check that the film is not cupping inwards because of the lateral guides squeezing to much

Posted by Samuel Andrew Wetzel (Member # 3759) on 12-14-2006, 02:55 AM:

Patrick,

With the Pro-35's the key phrase is preventative maintenance, they can perform as well as any other projector as long as they cleaned properly. I had this problem a while back at a 6-plex I service, after a while the adhesive from splices can attract a lot of dirt in the gate, to solve this problem I just took out the gate, cleaned the runners, and I told the projectionists to soak a q-tip in isopropyl alcohol and press firmly into the metal ridges in the film gate (left side if you're facing the projector) after every show, a lot of dirt seems to collect here on the PRO-35s, and if there's any dirt or emulsion built up in the gate it'll cause one side of the image to be out of focus compared to the other. Also, it seems simple, but check the distance setting on your anamorphic lens as well.

Posted by Thomas King (Member # 2745) on 12-14-2006, 06:23 AM:

Have a look at your lenses. When I noticed that we were't getting a flat focus, it turned out to be because some of the individual lens elements inside the lens barrel had become loose. If you gave the wide lens a gentle shake, you could hear it rattle! Carefully tightening the metal slip rings that hold the lens elements in place made a significant improvement.

Posted by Gilles Elbhar (Member # 3719) on 12-15-2006, 03:20 PM:

If you have 2 projectors,
Reverse the part(s) from projector A to projector B. Check difference.