Film-Tech Forum ARCHIVE: Dark sides in flat films.

This is topic Dark sides in flat films. in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Brandon Lokesak (Member # 2280) on 05-15-2004, 01:21 AM:

does anyone have any idea what could be causing our flat flims to have like a 4 inch dark side border to them. The left and right sides are extremely dark from top to bottom. Could this be due to the lamphouses being out of alignment. Its been like this ever since i worked there so it hasnt just happened. Its a cinnemacanica lamphouse with a lti 2000k bulb.

Posted by Mike Olpin (Member # 1115) on 05-15-2004, 05:19 AM:

It sounds to me like your flat aperture plate is cut incorrectly. You can order a new one to be cut, but that can be expensive. Alternatively, you can set new stops for your side masking to cover the dark area. (But don't pull them in too much!)

[ 05-15-2004, 08:13 PM: Message edited by: Mike Olpin ]

Posted by Steve Scott (Member # 630) on 05-15-2004, 08:44 AM:

What kind of projector is this, if it has a turret you may need to adjust the positioning of the lenses within the turret, or the whole assembly may be off some. If it's got a lens barrel, though, I'd agree with Mike, and check the plate.

Posted by Scott Norwood (Member # 30) on 05-15-2004, 08:55 AM:

If you have side masking, it could be that the masking stops are set wrong.

The best way to check any of these issues is to run a loop of RP-40 (aka PA-35) with the aperture plate removed. This will show you where the edges of the image are supposed to be.

Posted by Darryl Spicer (Member # 711) on 05-15-2004, 01:03 PM:

I agree it sounds like an aperture problem. In flat, issues with misaligned lamps usually mean hot spots on the image, since flat is a smaller aperture than scope. So I doubt very much that your problem has anything to do with the bulb alignment.

Posted by Jack Ondracek (Member # 1466) on 05-15-2004, 01:47 PM:

If you're runing an XL series projector with a trap, the gate might be adjusted to place the film too far from the aperture. That can cause this effect by itself.

Posted by Brad Miller (Member # 2) on 05-15-2004, 02:43 PM:

quote: Darryl Spicer
In flat, issues with misaligned lamps usually mean hot spots on the image, since flat is a smaller aperture than scope

Although this is probably not his problem, it could be that his screens have fixed masking at 2:1 and the lamp was tightly focused down on the scope format, creating dark sides on flat films.

Regardless Brandon HAS to post more info about his system for anyone to give reasonable advice. I am going to start instigating a policy where if someone posts a problem and does not list all equipment involved that the thread is deleted if this sort of thing continues. All it does is waste people's time. In this instance all we know is that a 2K Cinemeccanica lamphouse is involved. Well...what model lamphouse? What model projector is blocking the light in front of it? Is there a turret involved? Are the dark sides straight vertical, or is there a curve to the sides? Etc, etc, etc

Posted by Brandon Lokesak (Member # 2280) on 05-15-2004, 07:58 PM:

Its a century model SA. We have no side masking we have no lens turrent,The lines are perfectly straight down on both sides no curves. I dont know if its the apertures because its the same on both screens and the apertures are not in the wrong projectors. I dont know how much more information I can give to you about this problem. The apertures are rather worn maybe I will see about ordering 1 replacement for now to see if this fixes the problem. Sorry for the lack of information I thought I made it clear in the first post but I guess not. Sorry for wasting your time....

Posted by Brad Miller (Member # 2) on 05-15-2004, 08:25 PM:

quote: Brandon Lokesak
We have no side masking we have no lens turrent

That's great and all, but do you have any top or bottom masking???

Remove the aperture. Turn on the projector motor and xenon. Lift the douser (don't run it this way for very long - to be safe limit it to 20 seconds). Now tell me if you still see those dark sides or not.

Posted by Gordon McLeod (Member # 33) on 05-15-2004, 08:53 PM:

I guess I will ask my queery in this dilema Is this shadow a clearly defined dark band that is parrallel to the edge of the picture or is the shadow having a larger darker area in the corners than in the centre of the sides
If it is parrallel and clearly defined (the apperture in a SA is usually very sharp) then I would place bets on it being the plate or possibly the heat sheild behind it interacting with the lamphouse
If it is moreso in the corners then I would look at lamphouse alignment. And on that issue is this a older vertical cinemecanica lamphouse or the modern horizontal version and what make and model of lens is involved.

Posted by Brad Miller (Member # 2) on 05-15-2004, 09:01 PM:

TIP OF THE DAY - This sort of troubleshooting would be so much easier if people sent in picture tours of their theater. That way we could not only look at the make and model of equipment, but the way it is set up as well.

Posted by John Hawkinson (Member # 1135) on 05-15-2004, 10:30 PM:

Another useful trick is to pull out the aperture partially and watch if the effect follows it.

--jhawk

Posted by Jeremy Fuentes (Member # 2135) on 05-15-2004, 11:05 PM:

We have the same issue. Ballantyne projectors, with different types of lamphouses. Cinemeccanica, Xetron, Strong, and top, bottom, and side masking. Isco-Optic lenses, with turrets. It happens on all 5 of our screens, and they are all different size theaters. I actually fixed it on one of them once, by changing the lens, but our tech told me that I had the wrong lens in there, and switched it back to where it was, and took the other lens with him. I guess he thinks its supposed to be like that.

Posted by Brandon Lokesak (Member # 2280) on 05-16-2004, 12:15 AM:

Yeah I know pictures would be nice...It would be much easier if I could find the cable to my digital camera ill just have to take some photos tommarow and scan them in. In responce to the top and bottom masking question there is no masking.

Posted by Carl Martin (Member # 1146) on 05-16-2004, 12:26 AM:

it sounds like the picture is as good as it's going to be unless you get movable masking. with a shorter lens you could fill the screen side-to-side, but you'd be cropping the top/bottom (some people might prefer that alternative). there's a good chance you're cropping the sides of your scope image as well. what are the dimensions of the visible screen?

carl

Posted by Thomas Procyk (Member # 1170) on 05-16-2004, 10:42 AM:

My friend worked at a shoebox UA that had this "problem"...

All screens were 2:1 with no masking. The dark sides for flat were indeed caused by the apeture plate, but it was cut propery for flat. It was caused by -- surprise -- too wide of a screen with no masking. The trade-off was either cropping flat to 2:1 (which would undoubtedly cause a problem along the way, esp with subtitled prints) or just live with the dark sides.

As for wasting everybody's time, and the need for more info, it does get irritating when someone just says "I have THIS problem" and that's all. But it's equally as irritating reading part numbers and instructions for rewiring the building given to a newbie. "Oh? You're having a sound problem? Remove all the covers on the lamphouse and look to see if there's a GX-420 in there. If not, get out your Dolby Cat69 and your analog scope, insert the Align-o-Tron into the CP65, swap your DTS reader with your Dolby Digital reader, thread up the film and come back and report what happens. Oh, what model platter?" [Roll Eyes]

=TMP=

Posted by Steve Kraus (Member # 476) on 05-16-2004, 11:08 AM:

It's very difficult for an inexperienced person to know exactly what information is pertinent or not to the situation and while it would be nice if they simply listed everything that's there on the original posting and let the experts sort it out it's probably not realistic to expect that. There are just too many unknowns and invariably the experts are going to have to ask for more information anyway. For example, drawing on another thread, who would have thought you could have heat issues at very low wattages on a Century just because the gate was originally water cooled? Anyway, deleting threads just because a newcomer doesn't list all the facts right up front doesn't well serve the purpose of interactivity and communications. That doesn't, however, mean we can't all still yell at them for leaving out important details! [evil]

Posted by Brad Miller (Member # 2) on 05-16-2004, 11:22 AM:

Yell away, but time has proven that when things start getting ridiculous, make an example out of something and people tend to start paying more attention and we start seeing less posts such as "what's wrong with my sound" and nothing else to even give a clue.

(Sorry you ended up being the one picked on Brandon, but since you don't have a member picture, that makes you fair game. [evil]

)

Posted by Jeremy Fuentes (Member # 2135) on 05-16-2004, 05:57 PM:

So the agreement is that it is most likely either an aperture plate problem, or a screen size problem.

Brandon, word of advice, get a member pic ASAP! [thumbsup]

Posted by Steve Kraus (Member # 476) on 05-17-2004, 08:27 AM:

Well, personally I think it's someone standing on their seat just in front of the port holding up their hand in the two finger Rock'N'Roll salute or whatever it's called. That'll darken the sides every time! [Big Grin]