Film-Tech Forum ARCHIVE: 70MM Unsteadiness

This is topic 70MM Unsteadiness in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Richard May (Member # 2627) on 12-16-2007, 12:07 PM:

We have a Simplex 35/70 projector running at 30FPS. I cant seem to get the picture steady. It moves around all over the place. Mostly side to side but also some up and down movement. The bands seem ok. The guide rollers in the trap are working properly also. Any suggestions? Also, what is the proper gate alignment as far as how much it should close. I know it's adjustable with the stop screw on the trap. I cant find any info from the manual.

Posted by Brad Miller (Member # 2) on 12-16-2007, 12:27 PM:

Please, please, please call in an experienced 70mm tech. There are very few 70mm prints left in existence and once those are damaged that's the end of it. (Plus it sounds like you are running one of the extremely rare 30FPS prints!) This is just not something that should be troubleshooted via internet or a phone call. You could be doing all sorts of damage to the print that you don't even realize just yet.

Posted by Sam D. Chavez (Member # 1841) on 12-16-2007, 12:53 PM:

The upper loop size needs to be as small as possible on these as they are not true 70mm machines. If the loop is too big it will dance all over the place and cause all sort of weave.

Posted by Steve Guttag (Member # 268) on 12-16-2007, 12:58 PM:

I have not found the Simplex 35/70 to be particularly unsteady but the lateral guide system is a joke. The Machine seems to be based around 65mm rather than 70mm. I've had to cut some coils off the lateral guide spring to keep the film from curling around the runners.

Gate depth should be such that the runners stay about 1/8" from the aperture. Note the intermittent shoes should have 2-film thicknesses CLEAR of the intermittent sprocket or you WILL rub off any magnetic tracks that may be present. This is different than for the 35mm shoes where they will make contact with the sprocket.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 12-16-2007, 03:19 PM:

I wouldn't even run ANY 70mm on that projector.... 35/70 XL's have damaged more 70mm film than any other single projector out there. 35/70 projectors are a dime a dozen right now... trade it for either a DP-70 or Century JJ... that is my order of preference. A DP-75 wouldn't be too shabby either but don't forget that when you buy parts you're also paying a premium to keep Larry's plane in the air. Parts for 35/0 Simplex's are virtually non-existant. Strong has discontinued much of the odd ball or not sold in over a year parts that they normally used to stock, ditto for Ballantyne Pro 35 parts.

BTW: Panavision adapted the very first Simplex X-L way back when they were filming Raintree County in Camera 65 for MGM and yes they were screening 65mm dailies. They got rid of those X-L's and got DP-70's which are still in their screening room to this day. When Strong was producing the projector they never bothered to update the projector to actual 70mm width sprockets, gate and trap and rollers. Pretty pathetic!

Posted by Richard May (Member # 2627) on 12-16-2007, 05:12 PM:

Well, we have run 70MM on these machines for 7 years now without damaging a print so I'm not the least bit concerned about that. Looking at our other 70 projector, I see that the gate is about 1/8" away from the plate as you said Steve. On the projector that we are having the problem with, it more like 1/4" away or more. Interesting what you said about the shoe though. On both machines, the shoe firmly sits against the intermittent sprocket. I will move the gate in a bit and back off the shoe a bit in the morning as we cannot make any adjustments during the day because of refocusing issues.

Posted by Mark Gulbrandsen (Member # 72) on 12-16-2007, 08:53 PM:

quote: Richard May
Well, we have run 70MM on these machines for 7 years now without damaging a print so I'm not the least bit concerned about that.

How do you figure that? When you say this.....

quote: Richard May
On both machines, the shoe firmly sits against the intermittent sprocket.

Oh well too bad for the mag tracks on those prints....

Mark

Posted by Gordon McLeod (Member # 33) on 12-16-2007, 09:07 PM:

I have had on the whole good luck with the simplex 35/70 and very few instance of reported damage to prints
The week was it has a pull through penthouse

Posted by Steve Guttag (Member # 268) on 12-17-2007, 03:15 AM:

As usual, Mark is dispensing bad advise for Strong products. The Simplex 35/70 parts are not that tough to come by as they are virtually identical to the standard parts...which is actually one of the Simplex's weaknesses. It is a standard Simplex 35 with a bunch of spacers! As such, there are very few specific parts to the machine except things like sprockets and the 70mm gate parts.

A move to a JJ would not not alieviate a parts problem either because Strong would discontinue JJ parts as fast as Simplex 35/70 parts. I also dispute that the Simplex 35/70 has damaged more 70mm film than all others...the JJ most likely holds that title. The earlier upper loop stabilizer had a reinforcing rib that would scratch the film in the picture area, the infamous "JJ Scracthes" caused by leaving the 35mm pad roller in on the upper feed has caused countless scratches, the lower loop stabilizer has also contributed many a racing stripe in the middle of a 35mm image (way too narrow a relief in the RO-207 if the film has any curl to it). The there are the guides in the R50 soundhead that, if not properly set will also allow the face of the 70mm film to rub. Can a JJ be made to run scratch-free, sure but in terms of historical damage, they are way up there.

The Simplex 35/70 is not known for inherently damaging film but it is known for being particularly filmsy and with some of the poorest designs of the 70mm machines. The lack of proper 70mm width components, the Penthouse that is not properly spring balanced, and the intermittent shoe, which relates to the lack of proper 70mm width components that will rub tracks 2 and 5 down.

The penthouse is much maligned for not being driven...that really isn't that big an issue. Look at all of the digital penthouses...none are driven. The problem with the Simplex 35/70 (or at least the Strong version) is that they forgot to put in a spring to offset the effects of gravity on the tension rollers...thus they tend to sink to the bottom of their travel. The other BIG goof was the lack of head shields (both tongue and full shield) which allowed hums to come in from many sources...including its own changeover coil. Century also stopped including the full head shield, which was a mistake.

Steve

Posted by Gordon McLeod (Member # 33) on 12-17-2007, 08:11 AM:

On a side note
what were the diffeneces to the original Simplex 35/70mm machine (the GPL version with the penhouse with the curved top for the magazine to sit into and the older XL designed optical soundhead)
I have never seen any manuals for either the soundheads or that vintage of projector head

Posted by Steve Guttag (Member # 268) on 12-17-2007, 09:21 AM:

I dunno Gord...I do have an original cut-sheet on the Simplex 35/70 and uploaded here (go to the "Misc" section of the manual downloads). The soundhead looks to be a standard SH-1012T2 but the brochure claims 24 or 30fps operation. The Penthouse doesn't show enough to determine if the current design is the same with a different housing.

When I was at K-B Theatres in the 80s, we took delivery of a pair of some of the first Strong versions of the machines. The manuals on the 35/70s were a 100th generation dupe of hand-drawn sketches. This is particularly true of anything in the Penthouse area.

Relating to this topic, watch out for setting the gate depth. The 35/70 uses a different gate actuator link. The 35/70 link should be longer or you will run the risk of the gate actuator rotating past the stop. Also the 35mm gate must have the bottom edge chamfered or the 70mm intermittent sprocket teeth will hit it. Be careful.

Steve

Posted by Richard May (Member # 2627) on 12-17-2007, 10:20 AM:

Mark, we have never run sound on 70MM as our prints are for picture only. That's how I can say that. Sure, the shoe obviously has been set wrong and I will adjust it but other than that, the machines run great.

Posted by Paul Vollmers (Member # 927) on 12-17-2007, 12:08 PM:

Hey Richie,

What ya running in 70mm?

Paul--

Posted by Richard May (Member # 2627) on 12-17-2007, 04:18 PM:

3-D footage on 2 machines Paul. Okay so I tightened the trap locking screw a bit. It seemed to move the trap slightly closer to the gate. I also added a bit more tension to the bands and backed off the shoe a bit. Now there is only a very, very slight shake. The gate is still further away from the trap than the other machine and more than what Steve suggested. I will move it a bit closer in the morning and also re-adjust the shoe.

Posted by Frank Angel (Member # 248) on 12-17-2007, 08:57 PM:

Wow, 70mm 3D....on dual machines no less. Awesome. But you realize that what happens if both machines are unsteady with random motion; the viewer's eye muscles are going to be pulling the eyeballs in different directions, each eye following the movement of its respective image. Eyestrain is the name of that game. Sounds like you are getting to reduce it. Really try and get the problem resolved before you let in paying customers...you don't want your patron's eyeballs popping out their sockets. [eyes]

Posted by Robert Throop (Member # 61) on 12-18-2007, 09:28 AM:

The original Panavision modified XL's used Magnasync penthouses. I saw some of these machines years ago in Palm Desert, Ca.
Bob

Posted by Gordon McLeod (Member # 33) on 12-18-2007, 10:49 AM:

This is a picture from marty's widescreen museum site
http://www.widescreenmuseum.com/

that shows the magnasync penthouse

Posted by Richard May (Member # 2627) on 12-18-2007, 11:27 AM:

So I moved the gate further in and again backed off the shoe. Now the gate is at the exact same distance as the other machine. The shoe is not quite 2 film thicknesses away but it's better than it was. The picture now has no movement which I can see. Let's see if this holds up. Projector one has always been solid as a rock......................................................................
Just an update. It's been about a week and projector 2 is running fine. No shake at all. The only thing that is bothering me is that projector one's gate is running with the shoe well up against the intermittent sprocket. There is no shedding or shake so I am not going to adjust it. Again, since we run picture only I don't think it will be a problem. Thanks for all your help guys.

[ 12-24-2007, 09:09 AM: Message edited by: Richard May ]