This is topic Bad Apertures? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Aaron Flack (Member # 517) on 07-18-2000, 03:36 PM:
 
Hello

I am knew to this forum but and I think it it's great. I have only worked in the booth for several months so I have a reletivly basic question. I work at an old 8-plex and our Simplex 35 projectors are from the early 80's. Most of our apertures have been worn around the edges and they don't lock properly in place. Does onyone have any suggestions.
 


Posted by Tom Kroening (Member # 201) on 07-18-2000, 06:41 PM:
 
Just order a bunch of new ones. They cost like 6 or 10 bucks a piece i think. Use target film and have either you or your tech file it out to fit the screen (make sure there is some overspill onto the masking so you don't see the rough edge of the plate on the screen. Don't throw out the old pates til ou are sure the new ones work properly.
 
Posted by Trevor Bailey (Member # 75) on 07-18-2000, 07:01 PM:
 
Unless you're familiar with proper alignment procedures, I would suggest having a qualified tech do the work. A lot of people think that you can just grab a file and go at it, but I have seen some pretty bad plates and would strongly suggest getting someone experienced to do the work.

Not knowing exactly what you mean by worn, I would also suggest checking the trap to make sure it is holding the plate correctly.

Regards,
Trevor
 


Posted by Rick Long (Member # 213) on 07-18-2000, 07:50 PM:
 
I could not agree more with Trevor.

Remember in setting up apertures, the biggest part of the job is levelling the machine, centreing the image (and frame) for both Flat and Scope, and, if necessary, adjusting the masking to the proper limits.

Remember the old adage "The last thing you touch is a file".
 


Posted by John Walsh (Member # 168) on 07-18-2000, 10:16 PM:
 
I also agree to get a tech; or if that's not an option, learn about projector alignment and film format image areas before doing it yourself.

I have never heard of an aperture plate wearing out- projectors that are only 20 years old are still young if cared for.

Verify that there's not something on the projector that won't hold the plate, rather than the plate itself.
 


Posted by Randy Stankey (Member # 64) on 07-18-2000, 11:24 PM:
 
I have to agree with John W....

There may be sonething else wrong. On my Simplex XL, sometimes the plate won't lock in properly. You just have to make sure you've got it all the way in. Sometimes I have to wiggle it a bit. Make sure that little "pin" is all the way into its hole. Push the plate forward if you have to.

95% of the time I have no problems. I find that when I'm in a hurry is when it happens to me most. Sometimes I have to do lens changes on the fly. A lot of times we'll only be able to get flat trailers
 


Posted by Aaron Flack (Member # 517) on 07-19-2000, 02:30 AM:
 
What I mean by worn is the edges around the hole have degrated over the years. I have learned that lamp heat will do that. I know how they lock in the film trap because I have studied them; trust me. My real question is how to angle the image as straight as possible. Mainly the flat image. It never lines up properly with the screen and it drives me nuts because half of our apertures are loose hrizontally(meaning I can slide it around even when it's locked in place). Our Simplex machines are in great condition and the film traps look good as knew. We are in the process of getting our technitian here and I want him to examin each projector with SMPTE test film for sound and image. The problem is he's very hard to deal with(so I've heard, I haven't seen him yet), and he likes to blame other people for problems; but that's another topic I may post. I need an accurate sollution to fixing these image problems or our tech WILL NOT fix them!

By the way, I have read enough in this forum to know what not to touch; and I won't file the apertures. The question is will our tech fix the problem?
 


Posted by Michael Cunningham (Member # 210) on 07-19-2000, 03:55 AM:
 
I too have had trouble with Simplex aperture plate mechanisms. Mine are much newer, and only about 1/3 of them have this problem. On mine, the aperture plate has two holes cut in it and a motor slides the plates back and forth from Flat to Scope. Unfortunately, these motors seem to develop free play which cause the plate to drift a bit due to projector vibration. Our tech could find no reliable way to stop this from happening, so we just check and fix at each show start.

-Mike
 


Posted by John Walsh (Member # 168) on 07-19-2000, 10:27 AM:
 
Just to clarify a bit-

Aaron, you are talking about single format aperture plates, right? Which means you change lenses manually. The plate is a sort of "Z" shaped stamped brass plate with a black plastic (or bakelite-like) handle.

I am guessing that getting money from your management is tough. The right way to check apertures is to order a length of the SMPTE test film (35PA) and go by what it shows when projected. It comes in 50ft lengths, but sometimes equipment dealers will sell a short length (you would need about 10ft. or so.) Personally, I think it would be a very good investment, as it's good for several different uses. Maybe you could "sneak" a 10ft purchase in through petty cash? I have instruction sheets I can mail you showing how to use it, if you are interested. And you can order it from almost any equipment, so call several for a good price. Also, if you would rather not let that tech know what you are doing, don't use the place your company uses.

But if you are not allowed to spent that much, you might try this: Try to order Simplex part G-2306. This is an aperture plate that comes already filed out (it's actually punched) to the suggested 0.446" x 0.825" (flat) opening. You can use this as a *very* rough gauge to see if the image is centered and if there's any cropping. Remember, though, this is not the suggested procedure.

Also, you can see if a new plate is held firmly. If a new plate stays in place, you can try it on other projectors, proving to your tech that new plates are needed. If your tech is a pain, (again) maybe purchase it with petty cash from an out-of-state dealer.

Michael, you are talking about the turret model. If I remember, the motor pushes the aperture in for scope. When power to the motor is shut off, a spring slides it back to flat. So, if the plate drifts while in scope, it could be a motor problem; if flat- a spring problem. It can be fixed; I suspect someone simply doesn't want to spend the money.

Also, if the plates are silver-colored, note that the silver plating corrides, making it harder to slide.
 


Posted by Gordon McLeod (Member # 33) on 07-19-2000, 11:55 AM:
 
I never used punched out plates as I have never seen two that are centred the same
buy a pin hole and start to file
I also find a dremel tool helpfull in intially opening the plate up and then it s the Auger bit file and needle files to finish
 
Posted by John Walsh (Member # 168) on 07-19-2000, 01:34 PM:
 
It's true the pre-punched plates are always off for some reason, but I can't see them being more than 0.020" or so, unless something on the projector is also off.

My thinking was not to actually use the plate for regular shows, but rather a cheap test to if the existing plate(s) are indeed worn, and see if there's excessive cropping. You are right, though, it probably won't be centered when installed.

It's not as good as running 35PA, but better than guessing by eye, and for only $15 or so.
 


Posted by John Pytlak (Member # 331) on 07-19-2000, 02:45 PM:
 
A "dirty little secret" is that the outer diameter of the inner circle on the SMPTE Universal ("countdown clock") Leader "is approximately the height of a projector aperture having an aspect ratio of 1.85:1."

(See Annex A.4 of standard SMPTE 55).

I would caution that many of the leaders in circulation are copies of copies of copies, so they should not be used as a critical test film. For that, buy some SMPTE Projector Alignment Film 35-PA (RP40). It's available from equipment dealers and service companies, or directly from the SMPTE:
http://www.smpte.org/testmat/index.html

------------------
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 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
 






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