Just checking around with some literature I have around this place, I estimate $300 to add water cooled gates to this projector.

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Personally, I'm not a big fan of the shutter blower unless you're running a really "hot" 4000W or more. Water is your best option. Most xenon systems also include an additional in-line heat filter that's really required with 4kW operation -- be sure that's there as well.

(Boy, am I getting to dislike that picture...)

Pat

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A blower did the same thing, but some blowers are designed to blow on the back of the film, (while in the aperture.) When film stops in the gate, the heat causes it to bow back towards the light, which causes a slight focus flutter. The air blast pushed it back, reducing the flutter. Century called this their "Cinefocus" option. I don't if the Simplex blower just cools the gate, or also blows on the film.

Several lamps I used had heat filters in them. I don't know for a fact, but what I heard was that, with a heat filter, the light is reduced by about 10%, but the heat was reduced by about 50%.

I currently run 3000 watt Xetron consoles with Simplex projectors. No water cooling and no projector gate air blower. The gate is only warm when removed. Since my 3000 watt lamps run so cool, I was wondering why you feel water-coolers are needed. For example, are you sure that the regular lamp exahust is at the proper CFM level? Are you having focus problems?

I realize that you have 1000 watts more than I, but I personally thought that a combination of air blower and heat filter was the most effective for picture quality. The blower may also keep the gate/trap cool enough to prevent "hot fingers."

Note though, that I am limiting my comments to the 4000 watt range. If higher wattages are used, you actually need everything you can get.

Certainly, lamp exhaust and how much heat is coming out of the lamphouse are big factors. Water cooling helps in many regards, including keeping the trap cooler and minimizing expansion of the trap and aperture plate.

The G-4400 water cell isn't very expensive (less than $100, I believe)...when you order it...ask for the kit (I don't have the 52-xxxx number memorized). With the kit, you will get the water cell, hanger, nylon extension tubes with clamps and adapter tubes so typical water circulator hoses fit! That whole rig typically sells for just over a $100 street price.

To Pat: Has Strong considered adapting the 35/70 water manafold system for the 35mm only machines? The reasoning is that with the manafold, the trap is no longer held captive by the tubes.

Steve

Pat: I'm wanting to put an X-60C behind this classic PR1014. Gotta love that lamp. (especially as a ol' workhorse in a large indoor or in my case, an outdoor theater)

John: I just feel that the water cooling will be a good thing to have. (might run 4,500w-i'd like to have that option if a little extra is needed) We aren't running it yet. I'm still planning my drive-in booth.
Now if I could only win that Publisher's Clearing House on Super Bowl....

Gord/Pat/anyone:Is the air blower for focus, cooling, or does it serve a dual purpose?

I water-cool anything over 3000W, and would water-cool that as well if the customer would pay for it. In the tests I've done, water-cooling seems to do the best job of minimizing film flutter in higher wattage systems. Yes, I know it only controls the ambient temperature of the area around the film trap and not the film itself, but that really is what I've encountered.

4000W Systems always get an additional insertion-type IR Heat Filter. That gets a lot of extra energy out of the light before it gets into the film and is also very influential in the film flutter issue. I lose a little light due to the filter but I don't burn film and the image looks better -- I'll take the trade-off.

Air flow doesn't hurt as a cooling agent, but it's nowhere near as beneficial as water-cooling is. Heat filters and water-cooling are far better. I'd NEVER use additional air-cooling alone. It just doesn't cut it on larger xenon systems, especially with all the short focal length lenses and large-appearing screen images.

Air pressure does help a bit to hold film in position and minimze some types of flex. Remember Century's Cine-Focus? We still use air pressure on large format systems (870's and such) for that reason alone -- but no cooling benefit here at all. The shutter blower on a Simplex does a bit of that, helping to maintain the film's curvature, but the main purpose is plenty of air flow over the shutter and trap assemblies in high temperature situations.

Steve: I'd like to see a fixed water manifold on the Simplex but the design does not readily lend itself to that. Even 35/70 Simplexes have tubes attached to the traps. Century has always used the manifold design. I'll revisit the issue again but in this age of cinema equipment sales, don't look for a fast new design.

Chris: I love the X60-series as well. A big lamp and that's why it performed well, I think, just a lot of volume for the bulb to stay in a reasonable operating temperature range. It could use a little better airflow -- that little muffin fan in the corner worked okay when things were clean and booth exhaust was plentiful, but get some dust in the system and there wasn't enough airflow for me.

Pat: Yes I realize that the tubes are still attached on the 35/70 design. The big benefit is that with the manafold mounted just below the spot sightbox with just one cap screw, the trap can come out (with just the gate side of the manafold dangling by the surgical tubes. This will allow it to be cleaned more easily and the lateral guide roller lubed properly. The nice part about all of this is that all of the parts already exist. Either no or minimal adaptation is necessary for a 35mm only machine. Again, just an idea.

Steve

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"Old projectionists never die, they just changeover!"

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I always imagined that film is momentarily stationary in the gate while a given frame is being projected. I recently discovered that that isn't quite true.

What I understand is that as soon as the shutter comes open, the light heats up the film and it sort of "buckles" toward the heat source. (The lamp.)
The moment the shutter opens, the film is slightly out of focus. As it buckles it moves into the focal plane of the lens and sort of focuses itself. It takes a fraction of a second for the human eye to register the image so the frame is perceived to be in focus even though it didn't start out in focus.

Essentially that means two things:
1) The more wattage your lamp has, the more pronounced this is up to the point of not being able to keep the film in focus. (And eventually burning the film.)
2) You have to remember that even though film projection seems like a fast series of discrete events it isn't. It is a very dynamic process. If you don't remember this you might run into all sorts of problems when "working" in the area of the gate.

Kodak has done some great research on this and shown some of their results at a few conventions. Some of their high speed photography of the film as it's pulled-down and then hit with the light are impressive. The film is moving all over, though most of the motion is lateral (towards or away from the light source).

Remember that same film is subjected to light twice; once after pull-down, and then again after the "flicker" blade of the shutter uncovers again. That makes the film pull back toward the heat, then relax a little bit, and then pull back again before it moves out of the aperture. The lens is almost always looking at a moving image.

The industry has referred to this as "film flex" and it is typically a little worse in higher wattage applications. The interesting thing is that the film flexes whether there's a lot of light or almost none at all. Heat seems to increase the amount of flex that occurs.

While it's certainly not ideal, the reason you'll see more "slower" (higher f-number) lenses now as opposed to a few years ago is that slower lenses have a larger "depth of field". That means the film does not have to remain in the exact same plane for the lens to focus the film image on screen. The "slower" lenses accept the fact that the film plane flexes and that it is not fixed. When's the last time you saw an f1.7 lens used?

This affect has to be considered in the "faster lenses for more light" discussions -- you might get more light but image focus and sharpness becomes a problem.

You'll see this is most evident with a "soft appearing" image on screen, or one that seems to float between different points of focus. Chances are that flattening the light field a little (diffusing the heat), using a heat filter (reducing IR and/or UV energy), and using a water-cooled trap (reducing the radiant heat) reduce the effect by minimizing the flex of the film.

When the intermittent pulls down a frame, the film is still moving both vertically and horizontally; mostly vertically because of momentum/overshoot (jitter.)

While that's happening, the shutter opens. The heat expansion factors of the emulsion and the base are different- which means one expands more than the other. This causes the frame of film to buckle toward the lamp. (I imagine if running film with the emulsion away from the gate was the standard, the buckling would be towards the lens.)

There can only be one distance from the lens to the film that provides optimum focus for a given throw. I think you are right; when a person focuses the image, they are really placing the lens at a distance that is a happy medium between where the focal point would be if there where no heat, and the maximum distance the film will buckle.

Since the heat comes directly from the light, that is why I don't feel there is an improvement in picture quality from water-cooling. A heat filter and "anti-buckle air pressure" seem more effective. Hey, don't get me wrong; If you have the money get the water-cooler. It's just that it seems no theater wants to spend a dime more on anything, and if you have limited funds,

What I'm not sure of is exactly what happens on projectors with curved gates vs straight gates. The idea is good; curve the film to strengthen it, and it will buckle less. But, what about the lens? It can only focus in one place (that focal plane could be on a curve, I guess.) It seems you would need to order a lens designed for curved gates or a lens for straight gates.

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