Simplex 1050 image unsteady focus pulsing

[Kirk Futrell]

Hey all, we have a reel to reel setup with two Simplex 1050's. We noticed a while back that projector one does not look as sharp as projector two. When you run test film you can see portions of the film very quickly pulse in an out of focus. The whole image may be pulsing but I can only look at one portion at a time. This leads to just an overall less sharp picture. This is most noticeable in 1.85 as that is magnifying the issue the most. What's going on?
Things we have tried with the issue still occurring:

• Swap lenses
• Tried to swap gate but they are not manufactured the same and can't seem to be swapped
• checked lens holder for tightness (seems tight)
• adjusted tension bands from 1 through 5. (doesn't seem to help)
• looked at tension bands and they seem to be tightening together as normal. Tightening tension on worn prints definitely helps those prints in terms of steadiness and we rarely go above 3, but still focus pulse
• checked to make sure the gate with tension bands is tightly installed
• installed refurbished intermittent
• aligned shutter timing using test pattern (no ghosting)

What else should I check? I am not against checking any of the above things again if you are pretty sure they are the cause.

[Sean McKinnon]

Screen brightness, hot spotting, heat on the gate, dirty or worn tension bands...

[Sam Chavez]

I'm assuming curved gates? There is a stop pin on the inside of the gate which sets how far the gate moves into the trap. These come loose and you end up with too much tension on the film or not enough. I would run a loop of RP 40 or similar and adjust the gate stop to minimum without picture jump on both machines.

Any number of possibilities. Pictures of the gates would be helpful.

[Steve Guttag]

With the PR1050, curved gates are not a given. There was a definite run of them with straight gates. The PR-1050 was the one that had the lens turret swing open to allow rotation of the turret. It depended on the scope lens being heavier than the flat lens.

Not having interchangeable parts is an indication of an issue. Aside from how the contact parts wore, they should physically fit between the two.

Focus and light are very related. What condition the reflector/lamp alignment can have a big effect on final focus as will gate alignment relative to the lenses and, finally the lenses themselves.

[Mark Gulbrandsen]

I assume this must be at the Bel Court. The 35mm I've seen there has been just so-so quality, but hasn't deterred me from going there. It's a fun place to go see movies.
The best bet is to call a tech in that has a lot of experience with film projectors. He or she will have the required gauges, test film, know how to set trap depth, intermittent sprocket centering, and check other critical parts in the film path for wear, tweak the lens mounts, and do a sound check up. You may also find yourself dealing with the differences betwen Estar and Acetate prints.
I highly reccomend Steve, Sam, or the guys at Film-Tech. Who ever you decide to call in, be sure to have a variety of types of film laying around for testing purposes. I'm local, but sold off my test gear and am very busy being retired. I'd rather come and see movies there... The AMC here is just awful!

[Randy Stankey]

When you run test film you can see portions of the film very quickly pulse in an out of focus.

That is supposed to happen. To a lesser extent than what you're seeing but, yes, film does move into or out of focus.
It shouldn't be noticeable to the untrained eye. Even an experienced person won't see it unless looking for it. If it becomes noticeable to someone who isn't looking for it, something's gone out of whack.

Imagine: The film moves into the gate. The shutter opens and the film gets hit by a burst of light and heat. The two layers of the film, emulsion on one side and base on the other, expand at different rates as they get hot, causing the film to buckle. The emulsion, on the projector side, expands more than the base on the audience side and makes the film buckle toward the light. That's why you see the film change focus. The film is actually moving into and out of the focal plane (focal zone) of the lens.

Like I said, you shouldn't see this phenomenon unless you're looking for it. Film is projected at 24 fps. It's hard to see. If you can see it, something's wrong... obviously.

The first thing I can think of is, like Sean said above, there is too much heat on the film and gate.
It could be hot spotting. It could be a misaligned reflector. Maybe some component that makes up the light path is misaligned or needs repair. It, possibly, might be that the lamp is burning too hot. Does your projector have a cooling plate? (I don't think so but memory fades.) Is there air flow to let heat out? (Again, memory fades.)

Don't forget about the lens, too. The thickness of the lens's focal zone varies in proportion to its ƒ-number. If you put in a different lens, you might change the focal zone. Also, if the lens is out of whack. I've seen that cause weird problems.

You know, since the 1050 was made, lens technology has improved quite a lot. If you put a late model lens on an older projector you might start showing some of the projector's flaws that would have gone unnoticed in its day. Whether older lenses were better or worse doesn't matter, really. It's just that they have different characteristics.

But you said that you swapped lenses. You've, pretty much, ruled out anything to do with the lens. You've also cleaned, checked and tightened anything in the projector that might need looking after.

The only thing that I can think of that hasn't been ruled out is hot film.

[Ryan Gallagher]

I would agree with the others that optically this sounds like a trap/gate stop/tension/wear issue, or a hot-spot/field/lamp-alignment/focus heat caused film expansion issue.

I'm not versed with simplexes but that is where I would look first if this was occurring on one of our Centuries.

If the range of adjustment on the tension pads didn't fix it I would next...

Pull both lenses and check reflector shadow to lamp hotspot centering, look at them together A to B and see if one is vastly different etc, then re-focus lamps for a flat field with a scope lens being sure to get the corners and eliminate any central hot spot.

The above all assumes running the same lamps of similar age and tuned to the proper current, if one is running brighter/hotter than the other could also be a cause.


If that does not do it then I would suspect the gate tension pad tension/wear, or gate/trap assembly stops. If the gate tension is loose enough, or the stops have moved, it will allow the frame to jump out of the focal plane. If you can't swap gates or pads between the two machines to narrow it down, at least start looking for replacement pads?

The fact it is more noticeable with Flat makes sense of course, cause flat uses the vertical center of the film, and if it is moving when it shouldn't be in the Z direction the issue will be present in more of the picture, even if the movement is only a heat caused shift that is most pronounced in the center of the film. If the focus error seemed to be uniformly present across the field on even scope or 133 aspects, I would suspect the tension/mechanics more and less so a heat induced movement?

[Kirk Futrell]

Thanks for all the suggestions. I checked the lamp reflector focus by defocusing until I could barely see it and the issue still occurs. Even when the lamp focus is bright and uniform, I am able to touch the aperture plate near the opening and it is only a little warm, which makes me think its not heat related. I was able to swap the curved gates between projectors, with no noticeable effect. I think in the past I had trouble swapping the trap/tension side, but will try that again, and report back.

[Randy Stankey]

I agree. If it's not heat or hot spotting and it's not the lens, the trap and gate are where I would look, next.

Alternatively, try focusing more precisely. If you look at the projected image, carefully, you should notice that there is a ring-shaped area in the center of the picture where the focus fluttering seems to be most pronounced. Focus for that area instead of the center of the picture. Find the best average focus setting, starting in the donut then work from there.

You might be able to find an acceptable focus setting, that way. At least it will be good enough to get by with until you can work out what the actual problem is.

[Brad Miller]

Please post photos of the two gates and specifically note which one has the issue. I know there was one specific type of Simplex straight gate that required you to thread the upper loop a bit too big in order to get the film to lay flat in the gate. I am not a Simplex fan, so I don't have all of the specific variations and part numbers memorized, but I would know it if I saw it.

Also what size lamps? What kind of lamphouses? Is the reflector in good condition or is the coating flaking off? Is there a heat filter in place? If so, any chance the heat filter is installed backwards?

And what about the lateral guide roller at the top of the gate (about an inch or so above the aperture plate)? Does the inboard (non-soundtrack edge) guide roller snap back closed effortlessly if you push it open with a finger? Does it spin freely without any resistance? Its common for muck to get in there and the film can't push the roller open to the width of the film. (In the closed position it's something like 34mm of clearance and can be pushed open to 36-37mm wide for lousy splices to pass.) If it's "stuck" in the closed position, that will force the film to curl in the gate and you will have awful focus.

[Mark Gulbrandsen]

I noticed in the first post that you had already swapped lenses, but I had a few occasions over the years where the lens element securing ring had come a little bit lose and the lens elements them selves were floating around enough to cause an in and out of focus condition. So don't overlook that possibility.

Also, what Brad mentioned above. I've also had that happen numerous times. Mostly on the once a year service call type of customers... One was actually cleaning the gate and trap with some spray stuff and it got into that lateral guide roller's shaft and dried.

[Jim Cassedy]

I noticed in the first post that you had already swapped lenses,
but I had a few occasions over the years where the lens element securing ring had
come a little bit lose and the lens elements them selves were floating around enough
to cause an in and out of focus condition. So don't overlook that possibility..

Funny you mention that. I was going to bring this up too, except that he said he'd already swapped
lenses. Last year, I noticed one of the 70mm projectors here sometimes looked a tiny bit 'softer'
than the other, and there seemed to be a bit of 'image unsteadiness'. I could sense it wasn't an
intermittent sprocket or film gate/trap issue, but something wasn't right. It wasn't horrible but it
was noticeable. . to me anyway. And to make troubleshooting more challenging, the problem
seemed to come and go somewhat randomly.
By swapping lenses, I narrowed it down to a lens problem, and I finally tracked it down to one of
the retaining rings in the lens being slightly loose, causing one of the lens elements to move or
jiggle very slightly. It was such a tiny amount of looseness, that I'd only notice it during the first
½ of a reel. Once the lens element or maybe the ring heated up a bit, it expanded just enough to
hold it in place & everything looked fine. Tightening the loose lens ring fixed everything.

[Mark Gulbrandsen]

It's much easier to trace that down in a single projector system. And the lenses I had do that were all either Isco or Schneider...

[Sean McKinnon]

and what about the lateral guide roller at the top of the gate (about an inch or so above the aperture plate)? Does the inboard (non-soundtrack edge) guide roller snap back closed effortlessly if you push it open with a finger? Does it spin freely without any resistance? Its common for muck to get in there and the film can't push the roller open to the width of the film. (in the closed position it's something like 34mm of clearance and can be pushed open to 36-37mm wide for lousy splices to pass.) if it's "stuck" in the closed position, that will force the film to curl in the gate and you will have awful focus.

<----- this!

[Kirk Futrell]

Ok, I think Sam may be on to something with the overall gate closure adjustment. I noticed that there was a small gap between the intermittent shoe pad and the intermittent sprocket. Not sure why I hadn't noticed that before, but tightening the screw Sam mentioned allowed me to close the gap. But then I noticed that the intermittent sprocket actually can move laterally. I have tried removing the intermittent sprocket fastening screw (with the lines) and pushing it further in while bringing the sprocket and shaft more outboard to prevent lateral movement but it is at it's limit and still moves. I have read the manual section but it does not seem clear whether lateral movement is normal. It doesn't seem like it should be because it seems like it could create an unsteady image. The old intermittent and the one in projector 2 do not have any lateral movement.
I will try to put the old intermittent back in tomorrow because I don't think I can adjust my gate closure while the intermittent is slopping around. Please let me know if I am on the wrong track.

Once I have those thing in better shape I will try looking at the lateral guide rollers again. I did notice that projector 1 roller can move a little further inboard than projector 2 can but does seem to snap back in to place well.

Here is a picture of the gate and trap for reference.

film gate.jpg