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Topic: Aperture plate distances on various projectors

Brad Miller
Administrator

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

posted 10-23-2002 03:37 PM

An interesting discussion here has prompted me to initiate this thread. Could some of the gents here who have worked with a multitude of different projectors post their input on which projector models have the aperure plate positioned closer to the film plane than others, resulting in less aperture plate "fuzz"? I've never bothered to pay that close of attention, as changing out a projector on a site for this on reason is not an option, but such a listing could come in handy for new installs.

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John Pytlak
Film God

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

posted 10-23-2002 03:41 PM

If it is difficult to actually get in and measure the plate-to-film distance, you can measure the difference in lens position when you focus for the print image vs. focusing for the sharpest "edge" on the aperture opening.

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
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Brad Miller
Administrator

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

posted 10-23-2002 03:44 PM

If someone has actual numbers that's great. However I was actually expecting moreso for a answer based upon general findings such as "projectors A B and C are roughly the same, but D is noticeably worse and E is noticeably better", etc, etc.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 10-23-2002 06:42 PM

It almost has to be the original Christie P-35 straight gate....That aperture was VERY close. I could cut a plate on a "wrap around screen" such that the "fringe" area fell where it wrapped and didn't bleed onto anything around the screen!

Straight gates will always win in this regard.

As to Joe's snide comments on Simplex...the spacing between the aperture and film on the curve gate is adjustable. Now that the intermittent shoe is also independantly adjustable it is even better.

On key to look out for though is on high wattage, is to not have the aperture so close that the film could swell into the plate and blister the film (seen it happen on 4KW systems without heat filters).

Steve

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"Old projectionists never die, they just changeover!"

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Gordon McLeod
Film God

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

posted 10-23-2002 07:12 PM

The Norelco AA2 has a terrific distance between the plate and the film yet the fp20 and in particular the DP75 it is almost touching the film
The ernaman15 is way back yet the ernamman8 and9 are fairly close as are the Vic8's
Century C with the back plate is very close as well
I always angle the edges of the plate if possible to give a sharper line
Also the lamphouse can affect the fuzz amount. Longer working distances produce a sharper edge top the plate than some of the short distances lamphouses

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Josh Jones
Redhat

Posts: 1207
From: Plano, TX
Registered: Apr 2000

posted 10-23-2002 08:37 PM

I would guess that from the edge of my brenkert's aperature plate to the film plane(The gate runners) is about 2-4 mm. thats aweful close.

Josh

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"Film is made of silver, video is made of rust"
'nuf said

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Michael Schaffer
"Where is the
Boardwalk Hotel?"

Posts: 4143
From: Boston, MA
Registered: Apr 2002

posted 10-23-2002 08:40 PM

With all recent Kinoton projectors the aperture plate is very close to the film. They are only seperated by the plastic strips that the film runs on. Probably the gentleman from Kinoton America could provide information on their exact thickness (if that is the correct English term), when they are fresh. Of course they get slightly thinner as they are worn down slowly by the running film.

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Richard Fowler
Film God

Posts: 2392
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001

posted 10-23-2002 10:16 PM

The plastic runner is around 1.5mm in thickness......

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Sean McKinnon
Phenomenal Film Handler

Posts: 1712
From: Peabody Massachusetts
Registered: Sep 2000

posted 10-24-2002 12:10 AM

One theatre that I worked at had absolutely no masking for the 1.85:1 image and the edges on screen appeared perfectly sharp, Rachel can attest to this she knows *Exactly* what I am talking about.

It was a Century.... SA I believe (or maybe H i dont remember) but im pretty sure it was an SA.

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Pat Moore
Master Film Handler

Posts: 363

Registered: Mar 2000

posted 10-24-2002 06:49 PM

Millenniums are setup with around .015" between the film plane and the aperture. You can't get much closer because as the film flexes when the light hits it (well described by Steve G elsewhere), it generally flexes back towards the light source. In higher heat applications with the Gate closure set too close, you could find yourself scraping film. In Studios, where heat is generally a bit lower, that space might be closed down a bit more to minimize aperture shadow.

Pat

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Peter Hall
Master Film Handler

Posts: 314
From: London, UK
Registered: Dec 2000

posted 10-25-2002 05:44 AM

Probably the closese I've seen is the Westar (Century) with a manual aperture - is D shaped and fits seperately to a heat filter - I guess the manual Centurys are the same ?

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Brad Miller
Administrator

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

posted 10-25-2002 06:01 AM

How do the actual numbers on the Millennium model stand up against other versions of the Simplex and Century models regarding aperture distance? For a discussion like this, I think hard numbers like the Millennium info above are the best information.

Anyone have hard data on Cinemecannica, Christie, Kinoton, etc?

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