Film-Tech Forum ARCHIVE: Century SA

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Posted by Michael Elam (Member # 788) on 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.

Posted by Scott Norwood (Member # 30) on 07-02-2001, 07:59 PM:

This is probably something that you've already checked, but I will mention it anyway: Above the lens barrel on the inside front of the machine, there is a knurled knob with a set screw. This is used to shift the picture slightly to the left or right of the screen in order to adjust for 35mm mag prints or for slightly mis-filed aperture plates without having to move the entire projector base. Check to make sure that the set screw is tight. Also, check to make sure that the lenses are secured tightly in their collars.

Posted by Michael Elam (Member # 788) on 07-02-2001, 08:20 PM:

Thanks, I have checked both.

Posted by John Walsh (Member # 168) on 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.

Posted by Paul G. Thompson (Member # 655) on 07-03-2001, 12:28 AM:

Yes - it kind of sounds like the lense is flopping around because of the lateral adjustment knurled knob is loose. But on the other hand, I have seen some barrels so worn out that the only option was to replace the stupid things.

For the wear situation, the older Simplex XL's were almost, (but not quite) as bad as Century's.

Lense Bushings? Hmmmm.....Century's idea was not too bad, as long as they were round and not worn to a frazzle. Ballentyne Pro-35's were the best, and Simplex's older tin ones were a real POS! Unfortunately, some will not interchange with each other. Most anything will fit a BX-100. (just thought I would have to throw that in there)

Posted by Michael Elam (Member # 788) on 07-03-2001, 05:11 AM:

Well I see I am not completely crazy, I don't have a problem with the focus or indexed for the scope, it's just when you tighten the barrel
their seems to be so much 'extra room' that you end up tighting it to much. Why did they use a 4" barrel anyway? I wish I had the barrels that the Century C uses, in fact I wish I had some Century C's.

Posted by Gordon McLeod (Member # 33) on 07-03-2001, 09:41 AM:

There used to be a 4 barrel that had the hole offcentre to allow the apperture plate for scope to be cut in the centre and shift the image for top movable masking.
also if you overtighten the set screws on the lateral adjustment it can cause binding on the focus assembly
Also check the allen screws on the focus assemble below the mount
You reffered to a turret at one poin in the original post I haven't heard of a century 4" turret

Posted by Michael Elam (Member # 788) on 07-03-2001, 09:50 AM:

I know it sounds like a broken record, but I have done everything, everyone's suggested. Kelmar makes a conversion kit to adapt to a dual turret at a price tag of around $3,000 per unit.

Posted by Mark Gulbrandsen (Member # 72) on 07-03-2001, 01:12 PM:

Michael,
I have doen many of the Kelmar conversions on Simplexes, and Centurys...both SA's and C's. It works very good and is easy to set up and operate. Iahve always been for turretts in a theatre environment as it eliminates the handling of lenses and allows both formats to be in better alignment on screen. Personally , I don't care what other single lensmount addicts may say. Turetts can make a big difference in the on screen presentation quality in any theatre. If you are interested in the Kelmar please contact me for a much better than 3K price. Here is a picture of a model C that I completely rebuilt and converted.

MArk @ GTS
mark@getgts.com www.getgts.com

Posted by Gordon McLeod (Member # 33) on 07-03-2001, 01:45 PM:

I have had problems with certain lens not fitting properly in the kelmar turret especially some of the Sankors.
They will sometimes hit the front casting

Posted by John Walsh (Member # 168) on 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.

Posted by Gordon McLeod (Member # 33) on 07-03-2001, 06:10 PM:

The trend started so that the longerfocal length lens could pass more light as the diameter of the lens was limiting there fstop
Kollmorgen and others introduced 4" lens and anamorphs in 4" and up focal lengths mainly for driveins

Posted by Steve Guttag (Member # 268) on 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

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"Old projectionists never die, they just changeover!"

Posted by Mark Gulbrandsen (Member # 72) on 07-05-2001, 12:09 AM:

I just got done installing a multiplex with used Simplex's with single lens mounts. Personally, It was an absolute pain in the Ass! The operators in the booth hate them, and the chain owners have already confirmed that they will never do it again. Lens center lines are difficult to match up from scope to flat even with high quality lenses and good adaptor bushings. IMHO a big waste of time. Also there's the great possibility of dropping a lens and breaking or seriously damaging it. All in all these days lens turretts make more and more sense for every day operating theatres. There are situations that still demand single mount machines but I see that demand lessining every year.
The Kelmar holds alignment pretty well overall and so does the Millennieum turrett. There are easy mods that can be done to other Simplex turrets to make them hold alignment better. Most of the mis-alignment problems I see are from expansion and contraction of the actual theatre building from season to season, and or the building settling after new construction. This will cause the same amount of mis-alignment in any lens holder system.
Mark @ GTS

Posted by Michael Elam (Member # 788) on 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.

Posted by John Pytlak (Member # 331) on 07-05-2001, 08:20 AM:

Michael Elam said: "Dropping the lenses are a big problem, I am always buying new ones...the people in my booths never even heard of the word 'cleaning'...providing of course someone with some sense can change a plate and lens."

When it comes to having skilled and caring people in the booth, you get what you pay for. Replacing dropped lenses, ruined prints, and prematurely blown lamps can quickly add up to much more than paying enough to retain good people. The "bean counters" just don't get it!

------------------
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

Posted by Steve Guttag (Member # 268) on 07-06-2001, 10:40 PM:

Mark sez:

>>"It was an absolute pain in the Ass! The operators in the booth hate them, and the chain owners have already confirmed that they will never do it again. Lens center lines are difficult to match up from scope to flat even with high quality lenses and good adaptor bushings."<<

Steve sez:

If your single lens holders have the middle of the lens pointed at the center of the film and you lens adapters are also true...just how can the picture centers be different? It just aint possible! If your flat and scope pictures have different centers than your lens receivers are not centered with respect to picture center (chuck up your laser pointing back towards the film...lace up 35-PA and see if you are centered. If not, adjusting the upper lens guide can normally bring it to center. The rest is up to your lens adapter...if they are of the current type...they tend to be very uniform from unit to unit.

[added 7/7/01]

If all of that sounds too hard...then get one PC-Cine adapter. Both Schneider and ISCO have them. Schneider is currently working on one that will take 70.6mm dia. lenses that lets one adjust on one plane only.

Install the Scope lens in a regular lens adapter, point the machine for perfect center, install the FLAT lens in the PC-Cine adapter and adjust for perfect match.

[end of addition]

Again, single lens is about 95% of what I install...pain in the ass is not the way I would describe them...easy install is more like it! No double aperture plates either (the aperture changer is yet one more thing that goes out alignment).

I am surprised though...in over 20 years of dealing with single lens projectors...I can't remember the last dropped lens I heard about in my area...there may have been one or two but that is about it. I certainly acknowledge that the likelyhood is MUCH greater with single lens over turret....Oh wait...I remember the last dropped lens I remember...it was in the mid '80s and it WAS on a turret...I seems that someone took a Kollmorgan prime lens and screwed a Schneider anamorphic on it (those in the know will understand that the thread pitch of these two don't match)...any who...when the turret was rotated one day...."CRASH" the attachment hit the cement floor and killed it pretty good (dented the case and cracked the elements!)

I'll stand by that as an installer, I'd much rather install single lens over turrets...as an operator, "I" would demand single lens over turrets...as a dealer "Whatcha want?"

Steve

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"Old projectionists never die, they just changeover!"

Posted by Mark Gulbrandsen (Member # 72) on 07-07-2001, 10:32 PM:

Steve,
It is very typical for a scope lens to throw the image slightly one way or the other. This is due to the expansion factor of the lens and things not being perfect in grinding, and machining of the barrell. They are allot better these days thanks to CNC grinding and machining but all it takes in a scope lens to shift an image is literally in the several micron range of inaccuracy. Front and rear elements also have to be this close in alignment to be sharp. Next time you're installing even a new lens rotate it and see what I mean. New lenses do it to some extent but older lenses are even worse. Unfortunately in this booth it was all older scope lenses, old 4" adaptors, and this made for a more difficult time. Turretts would have made far more sense in this case, especially when you factor in the kids running the booth. I have yet to be in a facility that has dropped the lens either, but I have heard of it happenning.

John,
Unfortunately the glory days of having expert booth personel has ended in most of the world, I side with you that the bean counters don't even have a clue about it. It should be the other way around.....there should be no expert bean counters and good booth personel.
Mark @ GTS

Posted by Paul G. Thompson (Member # 655) on 07-08-2001, 02:43 AM:

Michael, as you know, dropping lenses on the deck is just unacceptable. Maybe you should advise those personnel who drop the lense to look for another job that requires less coordination. I would recommend Basket Weaving 101 in the community college.

Unfortunately, those personnel who drop lenses have several thoughts in their mind. Some are:
1. "I don't care - it is not my property."
2. "Tough ****."
3. They have no idea of what they are fooling around with.

I could go on and on...

Posted by Steve Guttag (Member # 268) on 07-08-2001, 09:31 AM:

Mark,

I haven't had the problem you are talking about with a lens per-say but lens adapters, sure. I would suspect one of the lens manufacturers to have more problems with this than the other. Even in focal lengths, one of the lens manufacturers thends to be more wild on the actual focal length from unit to unit. One of the manufacturers also can't seem to get their scope lens to be 2:1 expansion, more often than not it is wider than that!! If you check out my South Branch 6 photos in the "pictures" section, you will see that they are in single lens holders (the Kinoton way)...I used a mixture of Schneider and ISCO lenses...amazingly, they all centered up just fine! I also haven't heard one complaint about switching lenses/plates nor any problem of the pictures coming off center.

But back to your statement...fine, install the scope lens and point it at the screen for perfect center....install the flat lens in a PC-cine adapter and adjust for a perfect match...no lens turret same effect, much cheaper than retrofitting the turret. Heck with the cost savings, you could be buying a few spare lenses and some cabinets to hold the lenses....booth idiots aside.

From what you described, you were essentially putting in a system on the cheap...used projectors, used and not perfectly round adapters and used, less that state-of-the-art lenses. Sounds to me like the whole installation was allowed to be compromised to some level in the name of saving money...so what's the problem with shaving a little on the picture too...there is an allowable crop factor (10%) anyway.

I think we are just going to have to disagree on this one, my findings don't support yours.

Steve

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"Old projectionists never die, they just changeover!"

Posted by John T. Hendrickson, Jr (Member # 849) on 07-08-2001, 03:19 PM:

Noting Mark Gulbrandsen's rebuild of the Centruy with Kelmar turrett,we had two of our old Century SA's done this way. Our tech service did a hell of a job. Those turretts are rock solid and we havn't had a problem operating with them for the past year and a half.

We also installed some new milleniums, and have had to make some alignment adjustments on several of them already, albeit minor ones. All in all, we love the Kelmar turretts.

Posted by Gordon McLeod (Member # 33) on 07-08-2001, 04:08 PM:

I think I probably install more single lens vs turreted machines
I also rarely have alignment problems with them. And as for dropping lens well that hasn't happened either and if it did well I feel that is part of teh cost of doing business if you want to hire idiots for the booth

Posted by Steve Guttag (Member # 268) on 07-08-2001, 10:22 PM:

John,

In case any of my comments were inferred to reflect on Mark's ability to install or rebuild equipment...Quite the contrary, I have heard nothing but praise from his work and from what I have seen, there is no reason for me to think otherwise.

This is merely a discussion and expression of differences of opinions and findings...there is no absolute right or wrong here.

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by John T. Hendrickson, Jr (Member # 849) on 07-09-2001, 07:46 PM:

Steve:

I'm sure Mark's rebuilds are every bit as good as our techs. I didn't draw any conclusions from your pervious comments that they were not. I was only commenting on how pleased we were with the Kelmar turretts.

Incidently, I was skeptical about turretts and always favored single
lens installations until I encountered the Kelmars. So far, I'm impressed with them.

No offense taken, and keep "um happy down there on the Cheasapeake.

John