The problem that Josh is speaking of is from the bulbs, not so much the HVAC units. It is most noticable in our Kneisley consoles and lamphouses. Hard to figure, as everything in the booth is very well vented.

But we do also have 1 auditorium where the heat does affect the screen from time to time.

This phenomenon ALWAYS occurs at the TOP of the screen. If it were the 'bulb convections' (which in my previous post I claim is impossible (with the lens in) because they are nowhere close to the focal point of the lens) then they would occur at the bottom of the projected image as it would be inverted by the lens!!!

ITS THE HVAC, PEOPLE!!!

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If the observer seen it from the rear of the auditorium, it was probably from the HVAC.

If the observer seen the heat waves while sitting close to the screen, and the HVAC vents are way behind him, then I will concede they may have been coming from the lamphouse.

Which was it?

The trouble is, that a person has to look REALLY HARD, as if they were looking for something wrong. I spent a lot of time observing the screen with just light on it, and thats just it, a person has to "spend a lot of time" looking and looking closely.

Of course, if you take the lens out, a person can see the "heat waves" with no problem.

And again with the HVAC units, after reading this yesterday, I had to go look at ALL of the auditroiums and we do have a few where this is a problem when the unit is heating.

So again, both HVAC and bulbs are the cause.

Maybe if Josh wants to help solve our HVAC "heat wave" problem in those specific auditoriums, he can come in and help move the vents.

I actually came in here searching for problems relating to DTS matching some trouble that we are having. I loath DTS so much that I don't even want to explain it all. I just want to sift through the DTS posts. One problem fixed however, SCSI CD-ROM drives work just fine.

It can be seen when looking at a flame, say from a campfire. You can also see it in the ocean when swimming under water, near the surface during a rain storm. (The fresh water from the rain intermixing with the salt water.)

I have seen it in a CFS console many times and have always assumed that it was from the heat of the lamp. I, too, have never seen it in a Christie, or any other horizontal-style lamphouse.
I don't see why it couldn't be from the HVAC system, blowing in warmer or cooler air, though. It could even be caused by the heat rising off some other piece of equipment in the booth, such as a hot projector motor.

Now that I read this discussion, I'm not so sure as I once was as to the source. I can, however, propose a way to find out the source... a fan. When somebody sees the swirls from the schlieren effect, it should be an easy matter to take a piece of cardboard and wave it in front of the lens like a fan. If it causes the swirls to change or disappear you have found the source. Keep fanning in different places until the source is found. If you have tried all other places, inside the booth and outside then the last place would be inside the lamphouse. In this case I might figure out a way to place a small electric (battery powered ?) fan/blower inside the lamphouse and strike it back up. Again, if the swirls disappear or change pattern you have found your source.

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How many hours do you have on that specific lamp? Is it in just one house, or all 14? Is there a chance a blower in the lamp is running off-balance and shaking the crap out of your lamp? Is there a chance of a harmonmic vibration developing in your lamp? Is it occuring with on both flat and scope lense?

What you see on the screen with the lense in the projector does not sound like "heat waves" to me.....

And, yes, be careful about sending raw light through your lense. It could burn them up. A few seconds at a time, than wait a minute or two and let the lense cool down before you hit it again.

Karen at DTS

And as far as your DTS problems, all you need do is email me, I'd be happy to help. Don't be shy!

khultgren@dtsonline.com

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All equipment has troubles from time to time, but I can assure you from past experience with DTS, they will bust their butts to assist you with any problem the equipment developes. Their technical support is among the best in the industry.

I have to totally agree with Gordon. Many problems I have seen are due to operator error in one way or another. Perhaps a training seminar could solve some of your problems.

Why don't you explain the problem, and let's find the solution. That is one thing Film-Tech is about!

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