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IMAX aspect ratio: what gives?


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#1 Lindsay Mann

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Posted 10 December 2007 - 11:02 PM

I didn't see this anywhere on the site, I thought I'd post it because it's pretty interesting. http://en.wikipedia....of_film_formats

It's interesting to me that IMAX shoots on 70mm with spherical lenses. And I believe the aspect ratio is closer to 1.43 than Academy. Why would this be? So they can use the whole negative? Is there such a thing as an anamorphic IMAX movie?

What's also interesting is that people have been shooting 70mm+ since the late 1800's. What gives? What makes IMAX different? I know absolutely nothing about these earlier formats.

And p.s. "Super Duper 8" sounds made up.
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#2 Vincent Sweeney

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Posted 10 December 2007 - 11:47 PM

Note the screen's ratio next time you go to an IMAX film. There are basically two types with one being a more dome shape which requires a few projector modifications over the more normal looking screen. The frames originate from 1.34:1. In DMR converted films (ie Superman, Harry Potter) you will notice cropping depending on how they have reframed.

The IMAX process is basically different in that the 65mm film runs through the camera horizontally at 15 perfs for each frame. This gives a massive increase in resolution compared to other methods. IMAX represents more than just a larger frame however. It is a system of standards that include specs on things like seating arrangment and viewing angles, screen size and position and a complex sound specification that is more robust than your average movie theater.

Edited by Vincent Sweeney, 10 December 2007 - 11:48 PM.

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#3 Vincent Sweeney

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Posted 11 December 2007 - 12:12 AM

Or you could say the native IMAX frame is basically 4:3. I believe the actual 70mm projection is 1.31:1.
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#4 David Mullen ASC

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Posted 11 December 2007 - 12:33 AM

From Wikipedia:
http://en.wikipedia.org/wiki/IMAX
camera aperture: 70.41 mm (2.772″) by 52.63 mm (2.072″)
projection aperture: at least 20.3 mm (0.80″) less than camera aperture on the vertical axis and at least 0.016″ less on the horizontal axis...
...in IMAX the (projected) image is 69.6 mm wide and 48.5 mm tall.

---
This works out to be 1.34:1 negative, but projection can vary. The dimensions Wikipedia gives for projection works out to be 1.44 : 1.

The idea, started by Fred Waller's experiments with Cinerama, is to increase the size of the image so that more of it lies in the viewer's peripheral vision, while increasing clarity. This makes the image more immersive. Waller realized that most movie theater architecture would not allow the installation of a much larger screen in all dimensions, but could be modified to add more size horizontally, so he developed Cinerama to be a very large, sharp, widescreen image (2.66 : 1).

With IMAX, the screen is large enough to be increased in all directions, assuming you sit close enough for your peripheral vision to be engaged.
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#5 Vincent Sweeney

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Posted 11 December 2007 - 01:27 AM

This is an impressive format guide for general reference. Errors are probably present but it appears to be a good point to start from in research.
http://en.wikipedia....of_film_formats

Edited by Vincent Sweeney, 11 December 2007 - 01:28 AM.

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#6 Max Jacoby

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Posted 11 December 2007 - 04:24 AM

I don't fancy IMAX for storytelling and mise-en-scène purposes, the screen is so big that you cannot really play with compositions, on/off screen, selective focus, etc... Like David says, it is supposed to be an immersive experience, so everything needs to be sharp (huge depth of field) and you basically just point the camera at the scene and show everything.
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#7 John Sprung

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Posted 11 December 2007 - 07:03 PM

This is an impressive format guide for general reference. Errors are probably present but it appears to be a good point to start from in research.
http://en.wikipedia....of_film_formats

I can see right away that they have the aperture dimensions wrong for silent. The width reduction from 1.000" to 0.980" didn't happen until the Bell & Howell perforation was introduced.

The numbers given for Imax are correct, 2.772" x 2.072".



-- J.S.
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#8 Michael Lehnert

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Posted 12 December 2007 - 11:44 AM

And p.s. "Super Duper 8" sounds made up.


Unfortunately not: the Super Duper 8 or rather Ultra 8 format actually exists, although without being SMPTE or ISO-compliant, of course (like Ultra 16, if you want):

To get a lowdown on Super Duper 8, I invite you to read through this thread:
http://www.cinematog...?showtopic=2005

If you want to get some background knowledge straight-away, jump to this post of mine:
http://www.cinematog...n...st&p=195902

And as far as the questionable name is concernend, that was debated from this post onwards:
http://www.cinematog...n...st&p=196578

Pro8mm in LA, run by Phil Vigeant, sells a "Super Duper 8" or rather Ultra 8 camera under his own label (although it is actually based on the Beaulieu 4008-series) and calls the format now 'Max 8'. It was very critically discussed (and quite rightly so because if showcases some rather unprofessional approaches) in this thread here:
http://www.cinematog...showtopic=26352
...particularly from this post onwards:
http://www.cinematog...n...26352&st=20

Should anyone be interested in using Super 8 or even Super Duper 8 as insert cuts or more in fully-fledged feature productions or documentaries, please visit to the Super 8 forum here or PM me directly as I dare to put a "caution" sign up if one intends to use Pro8mm as first-port-of-call.
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#9 Lindsay Mann

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Posted 12 December 2007 - 10:28 PM

I don't think I've seen an IMAX movie since the 6th grade. I'm not one for the theater. I recently saw No Country For Old Men in the Union Square cineplex where the screen was slightly concave. It was so annoying. It made everything look like a fisheye, and it was either that or the story or the cinematography, but I immediately rushed out to see it again. :P
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#10 Paul Bruening

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Posted 14 December 2007 - 12:09 AM

I can't help but think of that scene in Soylent Green whenever I think of the wrap-around IMAX. "IMAX is people. It's peeeeeople!"
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