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Topic: Frame Drift?

Dave Bird
Jedi Master Film Handler

Posts: 777
From: Perth, Ontario, Canada
Registered: Jun 2000

posted 01-30-2001 10:09 PM

Ran some film through "#2" tonight (boy, she sure can pile up in the soundhead in an awful hurry if you've jammed your take-up belt!!!). Noticed a little bit of "drift" on the framing adjust, which also occurred with no film. But after I shut it down, I noticed that I'd started with it cranked all the way.

Let me see if I've figured this out. Frame adjust is meant to be started in the centre, and tweaked slightly as need be?????? Threading up with it cranked all the way meant that I never could quite get it back in frame (or to stay still). Also, it's spring-loaded. Is this to tighten it up? Should it be depressed when adjusting? Thank you.

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Dave Bird

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Ken Layton
Phenomenal Film Handler

Posts: 1452
From: Olympia, Wash. USA
Registered: Sep 1999

posted 01-30-2001 10:38 PM

What make/model is the projector in question?

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 01-30-2001 11:18 PM

Make and Model of projector? Sounds like a Pro-35 to me. if it is, it is a very easy fix. If it is a Brenkert, likewise it is a very easy fix. So is Century. Simplex? Ummmm-may be a little harder to fix.

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Dave Bird
Jedi Master Film Handler

Posts: 777
From: Perth, Ontario, Canada
Registered: Jun 2000

posted 01-31-2001 06:04 AM

Sorry fellows, they're XL's (black early to mid 60's).

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John Pytlak
Film God

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

posted 01-31-2001 06:12 AM

In general, the framing adjustment should normally be run in the center of its range. When threading, always be sure to advance the projector by hand so the intermittent is in the "dwell" (sprocket not moving) position, and then position the film on the sprocket in frame. If you've done this correctly, and have inspected the print to be sure all splices are "in frame", further adjustment of the framing knob should be unnecessary. IMHO, a skilled projectionist never lets the audience see an out of frame image.

Although the framing could theoretically be set up precisely and "locked down" using the SMPTE 35-PA (RP 40) test film, in reality, slight vertical shifting of the image may occur from print-to-print, depending upon the type of printer used. So final setting of the framing usually needs to be optimized for each print by actually looking at the picture on the screen. If you do need to adjust the framing, do it discretely, so the audience is unaware of the movement. And NEVER show the framelines.

Obviously, a loose framing knob that "drifts" on its own calls for repair.

------------------
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 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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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 01-31-2001 08:15 AM

Yes, usually the framing knob should be in the center of it's travel. If it's the same as most Simplex's, the spring-loaded knob can be pushed in, then rotated to center the word "FRAME." This allows you have a reference to return it if you were out of frame. (Tip 'o the hat to Brad for that bit o' info!)

There are a few tricks to lessen the audience seeing you adjust the framing, like (if) the scene pans down, you turn the knob at the same rate. Of course, if you are exactly 2 sprockets out, it's pretty hard to hide it...

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John Pytlak
Film God

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

posted 01-31-2001 08:53 AM

John Walsh said: "Of course, if you are exactly 2 sprockets out, it's pretty hard to hide it..."

Practice the correct threading and splicing procedures until you NEVER show the audience a frameline! That's part of being a skilled projectionist.

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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 01-31-2001 10:53 AM

Speaking of framing, does anyone know of a way to mark the framing knob on a Simplex to *exactly* show the correct position?

Where I work has adjustable top masking, which means the framing has to be adjusted when going from one format to another. Is there anything/anyway I can indicate where the knob should be for each? I have a peice of tape on there now, but it's really not accurate enough.

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John Pytlak
Film God

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

posted 01-31-2001 11:59 AM

John:

Another good reason to design theatres with constant height masking, and adjustable side masking. Common centerlines are much easier to handle.

Could you attach a long indicator pointer to the framing knob shaft to magnify the rotational position in reference to fiducial marks indicating the best framing position for each format?

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Scott Norwood
Film God

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

posted 01-31-2001 12:59 PM

Top masking is a pain. We had it at the Williamsburg Theatre (pics in the gallery here; it was an early CinemaScope conversion circa 1954), and switching from scope to flat/1.85 required a framing adjustment, while switching to Academy ratio required both a framing adjustment and an adjustment of the projector bases. This is one of the problems that results from trying to convert a theatre designed to show Academy-format films to adapt to the widescreen era.

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 01-31-2001 02:38 PM

With respect to the frame drift: When the frame knob is rotated, does it rotate "too" easily? Or do you have to use normal hand torque to turn it? Compare it with another machine that does not drift.

If it turns much too easily, it could be the collar or a "C" clip on the framing shaft assy became discombooberated. (made that word up myself) Or maybe a broken spring. It is basically an easy fix. If normal hand torque is needed to turn the frame knob, frame slippage might be caused by a problem with the intermittant. Roll the machine forward by hand, and see if you can feel any extra resistance when the pull-down cycle starts. It should roll nice and smooth without any noticable changes. If it feels like it is starting to bind, you better call for another movement, as what you have may be ready to cease up.
Also, without film in the machine and the film trap open, start the motor and then shut it down. If on rundown, it starts to give you the "Clunkity Clunkity Clunkity" thing several seconds before it comes to a complete stop, it would probably give cause for some very serious thinking about replacing the movement or finding out what may be causing it. These are just some things to check. Good Luck.

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 01-31-2001 02:43 PM

Scott, I have been yelling that for years!

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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 01-31-2001 03:24 PM

You'd have to see a Simplex to know what I'm talking about. The knob is on a long shaft that is under (but not part of) the shutter housing. There's no easy place to put a long pointer on it without the pointer getting in the way when you grab the framer. The pointer would have to be bent around the shutter housing and out to the front to work. Now, if it was a Century, it would be easy.....

Having adjustable top masking is a pain... but you need to 'play the cards you're dealt'....

I'm not *entirely* against adjustable top masking. (As Scott noted), this theater is older (designed for 1.33) with about 800 seats. The original screen area was 32ftW. x 24ftH. Customers demand bigger screens today, and would not be too happy with a 24ftW x 13ftH flat, especially in an 800 seat house. We adjust the lamp to be pretty even with both formats. There are beams to hold up the roof on each side of the screen, which can't be removed.

Has anyone ever motorized the projector pedestal to tilt automatically? That would do it!

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Dave Bird
Jedi Master Film Handler

Posts: 777
From: Perth, Ontario, Canada
Registered: Jun 2000

posted 01-31-2001 06:27 PM

I believe it only occurs when you start at the extreme end of it's travel (which, of course, you wouldn't do). But I can turn it WITHOUT depressing spring, so I wonder if that's a problem? When I started in the centre, I could only get it to drift if I cranked it all the way "up" to the extreme (it would migrate towards centre). (Not to worry, Shelly Long's "Outrageous Fortune" trailer is my perpetual "guinea pig", so I'm not ruining anything much!) Thanks all....

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Dave Bird

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 01-31-2001 06:34 PM

Dave,
The intermittent carrage that rotates is held in by two clamps. These are fixed metal clamps that cause uneven wear on the edge of the casting in projectors that are framed allot. They are a pain to adjust properly when the wear becomes uneven. One of the many fixes that Strong did was to get rid of the metal clamps and design a new spring type clamp to solve this wear problem. The spring clamp puts even tension on the carrage no matter what the wear is. This is also a good indication that the projector has been framed allot causing this wear. The spring clamps are cheap, around 2 bucks apiece and replacing them should eliminate any drift.
Mark @ GTS

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