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Topic: IMAX questions

John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 04-03-2001 01:35 PM

Some links to information on IMAX Dome (AKA "Omnimax") technology:
http://www.imax.com/innovations/theatre/dome/index.html
http://www.imax.com/raceforatlantis/tech.html
http://www.imax.com/films/distribution/echoes_of_sun.html
http://www.cfi-hollywood.com/process.html
http://www.amps.net/newsletters/Issue14/14_imax_.htm
http://www.most.org/omni01bb.html

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3686
From: Dallas, TX
Registered: Nov 2000

posted 04-03-2001 04:41 PM

Evans, not so strange! I lived in the Saint Louis area for 20-some-odd years and have been up in the arch only once, 5 or 6 years after I moved away!

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 04-03-2001 08:40 PM

For the record the arch is not an IMAX ® theatre but a World Oddessy Ultra70 theatre ( the only one in North America) This was the first cloned Imax projector by Niel Johnson

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3686
From: Dallas, TX
Registered: Nov 2000

posted 04-03-2001 10:02 PM

Actually, I was talking about going up in the actual monument. I've never been in the World Odyssey theater under it, but I have been in the history museum under it a couple of times.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 04-05-2001 04:38 PM

HAs anyone seen the 65mm 22 perf camera movement for sale on E-bay? This is perhaps the format that Imax should have used. Definately looks British and has that steam locomotive connecting rod look to it. I have to admit that it's a pretty cool piece! http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1227698812
Mark @ GTS

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Evans A Criswell
Phenomenal Film Handler

Posts: 1579
From: Huntsville, AL, USA
Registered: Mar 2000

posted 04-05-2001 09:09 PM

22 perf 65mm? That would give an aspect ratio of almost exactly (if not exactly) 2.00:1 ! I get that by taking 2.2, turning it on its side (horizontal travel) by taking the reciprocal, and multiplying by 22/5 . Since human vision is more oriented toward horizontal motion and since our peripheral vision is greater horizontally, this sounds like the ultimate system to use, but is probably prohibitively expensive and bulky for filming.

By the way, shouldn't 22 perf 65mm produce a frame length of approximately 4 1/8 inch (just a bit less than that), and not 3 1/4 as the information on the ad says? The 2 1/4 figure seems reasonable (camera aperture on Todd AO was 2.072).

Evans

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3686
From: Dallas, TX
Registered: Nov 2000

posted 04-05-2001 10:12 PM

A print frame of 15 perf is about 2.75 inches, so the 3.25 number sounds right.

Editing: Uh, never mind. (2.75/15)*22=4.03 inches. Duh. No wonder I was a comm major!

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Evans A Criswell
Phenomenal Film Handler

Posts: 1579
From: Huntsville, AL, USA
Registered: Mar 2000

posted 04-05-2001 10:30 PM

Then somewhere, my mathematical reasoning has gone awry. If 15 perf is about 2.75 inches, then 22 perf should be 2.75 * (22 / 15) is 4.03, which is just less than 4 1/8 as I figured it would be in my last post. What gives? Where is my logic going wrong?

Editing (after Adam's edit): Thanks, Adam, I thought someone had discovered non-linear film!

Evans

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3686
From: Dallas, TX
Registered: Nov 2000

posted 04-05-2001 10:35 PM

Too much Imax 3D!

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 04-05-2001 10:36 PM

The perforation pitch on 70mm print film is 0.1870 inches. So 22 x .1870 = 4.114 inches, which would be the length of the "pull-across" in any projector. Of course the projected area would be slightly smaller due to framelines.

For the 15 perf IMAX film format, 15 x 0.1870 = 2.805 inches pull-across.

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3686
From: Dallas, TX
Registered: Nov 2000

posted 04-05-2001 10:43 PM

Thanks, John. I'll keep that number handy.

For our one-year anniversary, one of our theater directors asked how many feet of film we had run through the projector. After staring at him for what felt like 20 minutes, I just slapped a wooden ruler on a piece of film and guesstimated the rest.

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