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This topic comprises 2 pages: 1 2
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Author
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Topic: Century SA
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Michael Elam
Film Handler
Posts: 84
From: Clarksville, IN, USA
Registered: Mar 2001
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posted 07-02-2001 07:52 PM
I have a 12 screen complex about 15 years old, the equipment has been badly abused during this time. The complex has Century SA's with the
4" lens barrel. My problem is there is so much 'play' in them when I insert the lens, cut the plate, pull the lens out and put them back in, each time the image moves in some sort of direction, never the same however, usually this happens when the turret lock down screw is tighten, it seems that each time the tightness is actually different and moves the lens in a different direction. It is bad enough that the screen image ends up outside the plate. I am using reducers with stops on it, that part is ok, it's just when tightening the screw it moves,otherwise they are great machines, I love them !, it would help if the local operators would just attempt to maintain them the way they are meant to be.I think there is just to much movement inside the
barrel.
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John Walsh
Film God
Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999
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posted 07-02-2001 09:04 PM
I have found that many of those 4" to 2 25/32" adapters (Century calls them "bushings") are machined poorly (out of round). Also, the lens barrel and clamp assembly, too. This is especially true of projectors and parts made around that time (15 years ago.) We had the exact same problem with projectors we bought in 1982.We found there's not much you can do, but if you have some time, there are some things that might lessen the problem. Put a mark on the lens clamp knob so people will tighten it to the same position every time. Swap the bushings around the projectors - you might find some will work better in another projector. Ensure the bushing fits in as far into the lens barrel as it can. Depending on the focal length of the lens, it may not be possible. If it looks like you can, even if the film will focus, still check that you can open the gate without hitting the lens. On some bushings, you add a collar around the bushing to stop it from sliding in - it puts the lenses at the same focal position. There is a thick pin (on the projector casting) that orientates the lens. However, you can get the bushing to go in about 1/2" farther. You get rid of the collar and use the bushings that have a pin in them already. This is what that little notch is for in the lens barrel (located at the "9-o'clock" position) if you look at the projector front. A thin pin is placed on the side of the lens bushing and fits in that notch. If the bushings are originally made by Century, there is a place to put the pin in. None of these ideas are very good, but there's not much you can do without replacing the lens barrels and bushings. As Scott mentioned, on that knurled knob above the lens, check the set screw is tight. But also, there are two smaller set screws on each side of that knob. (They are a part of the lens barrel casting.) Those two screws should be set just snug - such that they keep the lens barrel from moving left/right, but not enought to prevent you from rotating the knurled knob to shift the picture.
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John Walsh
Film God
Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999
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posted 07-03-2001 05:19 PM
Yes; no question that turrets are better for the average multiplex theater, and some screening rooms, too. Both lenses have individual focus settings, so each stays in good focus. Much less chance of people dropping them, not to mention keeping the odd finger print off of the elements.It looked like 4" lens holders started with 70mm projectors (they needed a bigger peice of glass to take in the wider film image.) I don't know which projector company provided them first, (Todd-AO?) but they seem to have come out in the middle 1950's or so. I'm not sure why they put them on 35mm-only projectors, unless it was just to not have to manufacture two different lens holders. Or, maybe they thought they would start using 4" lenses for regular 35mm to get more light.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 07-04-2001 12:03 PM
Oh now this is just too juicy to pass up....Turrets being better than single lens? A myth at best...in some situations they do indeed make more sense (turrets) but like all else in life, they bring with them their own short comings... I have yet to find a turret that holds it's position well...most swing open and close and introduce slop with time and can vibrate while the projector is in motion. My least favorite to-date is the Xetron Ernamann offering...this thing is so piss-poorly designed that the turret vibrates from the projector/console (both contribute, believe it or not)...the turret is overhung so it gets a leaver action to magnify the vibration...end result...pictures that shake (aperture shadows too)..every machine is different in steadiness based on how out of balance the console's blowers are and the dynamics of the projector itself. Of the theatres I have serviced with turrets...there are the above mentioned Ernamanns, Century with old and current style turrets, Simplexes with the PR-1050 and TU-2020 (Millenium and PR-1060), Cinemeccanica and probably others that I have forgotten at the moment...they ALL developed misalignements and often are never really set up as well as they could be (ie getting the turret square to the film gate). More often than not, the focus rack on the turret is inferior to it's single lens couterpart...thereby the image shifts as it is focused. There is no question that in the hands of the uncaring, turrets are going to be more lens friendly and the scope lens has a better chance of being oriented correctly. With the current Simplex lens bushing, the lenses settle into a Simplex PR-1014 just fine each and every time. Kinoton also makes an exceptional single lens system that doesn't subject the anamorphic attachment to potential twisting...the lens registration is very good from insertion to insertion. Ironically, Christie made a VERY good single lens system for their P-35...very similar to the Kinoton and would always come up the same every time....I'll take a picture of it and post it kinda cool. The bottom line is, chose the best system for your particular needs...if "Flat/Scope" is all you do and the booth personel is towards the lower quality side or you have a mixed flat and scope show, turrets have many advantages...but .... if you run 4+ formats have good booth personel and run good equipment, single lens is the clear winner. Oh and 4" (101.6mm) lens holders...Gord is right...while trying to achieve bright pictures and using fast lenses (f/1.7) 4" lenses are required on long focal lengths....you will also find that on super short large format lenses you also fall into the 4" diameter lenses. Another desire for 4" lens receivers is to use persepective change adapters (both ISCO and Schneider offer them) to minimize keystone effects or to ensure all formats from all projectors center on the screen. One nice thing about Kinoton projectors with single-lens is that you get the lens holder for the lens you are using...no adapters Steve ------------------
"Old projectionists never die, they just changeover!"
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Michael Elam
Film Handler
Posts: 84
From: Clarksville, IN, USA
Registered: Mar 2001
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posted 07-05-2001 07:46 AM
Dropping the lenses are a big problem, I am always buying new ones,
but a good thing about turrets, especially if you are using top masking, you can adjust each lens as needed for the best picture for the correct format. I'll admit there are problems with the lens roatating and stopping in the correct place,same for the apreture plate,(especially with Christie) but most of this is due to proper cleaning, the people in my booths never even heard of the word 'cleaning'. Personally I like the side movable masking the best,
if all houses would be like this single turrets would be ok, providing of course someone with some sense can change a plate and lens.
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