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STATS SCREEN SIZE

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75 FT WIDE AND 45 FT HIGH.THROW FROM BOOTH 78 FEET...

For this size what kind of projector (35 mm) would you put in????

Hey slap:

If you're using a flat white screen use 4500w or higher. For a projector get a Simplex Apogee with a free-wheeling sprocket modification for the lower loop. I had one in my last theatre. Steadiest picture I've ever seen. If you can't afford a new projector my second choice would be a Christie. Both use metal straps in the gate and really hold the film steady.

When John Pytlak was with us, this was a frequent subject. His comments are:

Much depends on the efficiency of your lamphouse, shutter, lens, and port glass and the gain of your screen. Based on the Strong "Lens Selector and Picture Size Computer", a good "rule of thumb" is approximately 5 watts per square foot of screen area for a matte white (gain=1) screen, two blade shutter, and typical lens and port glass.

Based on that, you'd be looking at nearly 17,000 watts. As that's probably not practical, it looks like you'd need a serious lamp and a gain screen, if you're trying for standards. We have screens like that in Seattle, and they're all running 7k bulbs in newer Strong or Christie SLC consoles.

As for a projector, I'm not sure your screen size makes the decision that much different. Jitter on any projector will look worse with larger images, and all projectors can have it.

With a Century, Simplex, or Christie, you probably wouldn't be able to tell the difference. I'm told that higher wattage installs are best with curved gates. Otherwise, one machine is probably as good as another.

I would use a electronic shutter kinoton as they have the highest light effciency and there lamphouse out perfome all others

Also is this an indoor or a drivein
If it is an indoor a curved gain screen will also improve the image quality

IT IS AN imax REDO.........

Ahhhh... out of my area. Gordon can probably help you there. If it's 70mm though, that would allow for larger bulbs.

I have used up to 7k for 35mm though I know Kinoton has done 35mm with a 10k lamp for a disney screening
I would look for either a Ultra80 Strong 7K with a Simplex XL projector that has been fitted with a high speed movement
You will not want to attempt to fill the entire height of the IMAX screen
Usually just the width in Scope and maintain a constant height image in flat

Are XL high-speed movements still serviceable? I was told they were hard to get parts for.

I would like to keep the 75 lenght but with will need to be smaller

A typical IMAX screen 75' wide will be approx 56' high
Yes if it was a gain screen you could with 7K produce a image that is 75' wide x31' heigh and a flat pix 57 wide by 31 high
you would not want to attempt going any bigger than that as you must also remember that a IMAX theatre is typically the screen width = the length of the building and for 35mm it is recomended that one be seated no closer than 1/2 the pix height so that means the front row should be no closer than 15'
Also becasue the screen is effectively square to prevent keystone of the image you will have to centre the image on the sheet and as such you will have a lot of unused area under it and that will also cause a loss of usable seats to prevent the discomfort of necks being held for long times looking upward
Phillips in the sixties did tests on theatre comfort and determined that the max upward angle one will tolerate for any time frame is upward 30 degrees from horizontal
beyond that neck strain will set in

Gordon thanks so much for that info it is a big help........

We had a 70 foot screen at a theatre I used to manage. We had a Kinotone, high speed shutter, etc. as described above. We had a 7000 watt bulb. Nice image on the screen

update--We went with the APOGE projector....What a picture ...Many said we could not pull off such a large picture with such a short throw...Crystal clear..

Good choice slap. Congratulations and good luck.