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Topic: Purple Line On Screen?

John Westlund
Expert Film Handler

Posts: 204
From: Burney, CA, USA
Registered: Jun 2001

posted 10-22-2001 11:58 PM

There is a purple line on the left side of the screen. The line seems to come and go and seems to be more visible when the scene is dark. The projector is a Century SA. Is there anything you guys know that I can do about this problem? Thanks
John

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 10-23-2001 01:20 AM

Your aperture plate is opened up past the 825 line. Contact your tech to see about having him cut a new plate. I don't know the exact reasoning as to *why* this is, but I'll betcha Mr.Pytlak can tell us.

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 10-23-2001 01:21 AM

Sounds like you are seeing the edge between the picture and the soundtrack information...Check your aperture plate or projector alighnment could be slightly off causing junk ti hit the screen instead of the masking.....

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Rick McCluney
Film Handler

Posts: 66
From: Ocean Springs, MS, USA
Registered: Nov 2000

posted 10-23-2001 01:24 AM

Sounds like the aperture plate may not be pushed all the way in.

Rick

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Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99

posted 10-23-2001 02:12 AM

I vote that the aperture plate isn't aligned right. Chances are you can wiggle it back into place.

If that doesn't work, pull it completely out of the projector while it's running. Look and see if the picture is lined up on the screen correctly. That part of the soundtrack you are talking about should be completely off the screen and showing only on the black part of the masking. It it's intruding onto the screen, it's not your aperture plate that's wrong but your lens adjustment. If you run some film through the projector (while there are no customers) you can eyeball the thing back into alignment well enough to hold you over until your technician can come out and run some RP -40 test film to do the job right. Test film is the only way to do the job right. Eyeballing is only meant to be a "Band-Aid" measure.

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 10-23-2001 03:01 AM

Ah yes, silly of me for not thinking of that most obvious probable cause. Cast me as a 3rd vote for the aperture not being slid in all the way.

If that's not it, then check the eccentric lens or turret alignment (the aperture would still be overcut if that was the case). Finally, go for a new aperture.

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Joe Redifer
You need a beating today

Posts: 12859
From: Denver, Colorado
Registered: May 99

posted 10-23-2001 04:18 AM

I'm guessing that this has something to do with the aperture plate.

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 10-23-2001 05:53 AM

Possible temporary fix: file down (ever so slightly) the edge of the aperture plate farthest away from the operator (the outside edge, not the edge within the picture area). This will let you push the aperture plate in slightly farther than you can now and will cause it to cover the blue line on the soundtrack edge. Before doing this, just make sure that the non-soundtrack-edge of the plate is not also overcut.

Before doing this, make sure that the problem occurs with more than just one print. It could be tha tyou have a print (or, more likely, a reel) with an improperly applicated soundtrack.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 10-23-2001 09:04 AM

It is also possible since it comes and goes they are seeing the effect of the soundtrack applicant that has bled over the soundtrack and into the pix area. When the industry finally switchs to cyan tracks that problem will be a thing of the past

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Joe Beres
Jedi Master Film Handler

Posts: 606
From: Minneapolis, MN, USA
Registered: Nov 2000

posted 10-23-2001 09:12 AM

You are all potentially correct, but Gordon has a good point. I actually have some perfectly machine cut plates that work better than any of the hand-filed plates I've used over the years. But, every once in a while, I will see the effect that John described. In these rare occurences, I just try to move the screen mask just right so that it covers the left edge of the screen just a hair more than usual. It makes annoying (almost pulsating) purple edge a little less noticeable.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 10-23-2001 10:42 AM

I suspect either the aperture plate is not seating properly, or was not filed correctly. Before making any changes, check the projected image area using the SMPTE Projector Alignment Film 35-PA (RP 40). The proper width for both "flat" and "scope" today is the 0.825 inch width markings. Seeing the dark blue or magenta stripe at the left edge of the image means you are seeing the analog/DTS soundtrack area.

------------------
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

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 10-23-2001 12:24 PM

839 is still supposed to be clear of any problems as many theatres still are set for that size

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Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99

posted 10-23-2001 12:26 PM

The left-right (inboard/outboard) alignment of the aperture plate on a Century SA is regulated by an eccentric stop. Modifying the plate would likely prove useless.

The reason I mention that the lens alignment (eccentric adjustment) might be screwed up is because on turret projectors, people have a have this habit of grabbing hold of the lens in order to move the turret by hand. (There are plenty of times when you have to tweek the turrets on those centurys.) After a few times of doing that, the lenses and their adjustments often get out of whack. The old Simplex TU-2000 turrets are the same way.

I spend a lot of my time aligning things that are messed up in that way. Once I get it pounded into peoples' heads that they shouldn't use the lens as a handle, I spend a lot less time realigning things in that particular theatre.

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 10-23-2001 01:26 PM

I should mention that I was assuming that the original poster had a non-turret Century. (Actually, I've never seen a turret-model Century anywhere except in photographs...they must not be very common.)

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John Westlund
Expert Film Handler

Posts: 204
From: Burney, CA, USA
Registered: Jun 2001

posted 10-23-2001 01:41 PM

Scott is right. The projector does not have a turret. I will try the things you told me. I think the aperture might not be fitting all the way in. Thanks. John

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