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Aspect Ratios


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#1 David Regan

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Posted 01 June 2007 - 09:44 PM

So I've just got a few questions of clarification regarding aspect ratios. There are so many, and seem to have changed many times over the years with regards to SMPTE standards and projection issues, that I have had some issue keeping them all straight, and just wanted some clarification on some of the more seemingly common aspect ratios.

Anamorphic, as I understand, is a widescreen format that is squeezed during production by using anamorphic lenses, which squeeze a widescreen image into a full frame, to utilize the entire frame area. Then during projection it is unsqueezed by another lens, resulting in an aspect ratio of 2.35:1 or 2.40:1. Is this correct, and I gather to shoot anamorphic you can only use anamorphic lenses?

Super35mm. As I take it this is just a widescreen format with a ratio of 1.85:1. I'm just confused over the difference between Super35mm and Standard35mm, because as I take it from reading Super35mm still prints on regular 35mm stock. (I could have read wrong of course)

As for all the other formats, be it widescreen 1.66:1, 1.85:1, or standard Academy 1.37:1, what actually dictates how it is shot. I know you can mask the aperature, but I understand this is often not preferred. So is it just a matter of the DP framing according the what he knows he wants the aspect ratio to be, and go by the groundglass, and then it gets masked in Post?

I know its a pretty basic subject, just its kinda a headache for me to get my head around.

Thanks for any help.
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#2 timHealy

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Posted 01 June 2007 - 09:56 PM

to shoot anamorphic you can shoot a full frame aperature with an anamorphic lens or shoot super 35 with a normal spherical lens. You would have to blow up the Super 35 print a little but negative is so good one can hardly notice. I believe shooting Super 35 one can do three frame pull down or a normal 4 frame. But you can frame for anamorphic cropping a little and losing a little negative area. One has the choice to shoot with the lens centered or use a common top header. One can also shoot techniscope which is an older 2 frame older pull down method.

Try a search on this subject it has been talked about before.

Tim

http://www.panavisio...spect_ratio.php

Edited by timHealy, 01 June 2007 - 09:57 PM.

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#3 Jon Kukla

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Posted 01 June 2007 - 11:17 PM

When you are dealing with theatrical film projection, the ultimate masking will always occur in the projector. Projection booths need to have different individual prime lenses for each format, in order for the image throw height to be consistent. Each of these lenses also needs an aperture mask, which mattes out the perforations and soundtrack from impinging on the projected image. This is why standard projection apertures are always slightly smaller than camera apertures.

Another important point to note is that aperture masks are almost always customized with a metal file to compensate for the characteristics of the booth/screen combination, such as slight image bleed or keystone effect. And then there is the concept of racking, where - especially with non-anamorphic prints - the projectionist can accidentally show too much of the top or bottom of the image, thus re-framing it. This is why booms, stands, and wires are often protected for the entire frame, even when the ground glass is much more restrictive. (It also allows for the dreaded open-matte "full screen".)

As a partial check against these variations, some DPs have been known to insert a hard matte inside the gate in order to somewhat reduce the likelihood of gross misframing. The most common practice I've heard of is to use a 1.66 matte, since it still allows for reframing in post if necessary.

Hope this hasn't muddled it up further. But the short answer is that unless the print is anamorphic, then the chances are pretty good that most or all of the Academy frame has image information, even though much of it may be intended to be cropped in-projector (soft matte). Most cameras tend to shoot full silent gate regardless of format (unless the hard matte is used).
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#4 David Mullen ASC

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Posted 01 June 2007 - 11:27 PM

If the print is anamorphic, it has a 2X squeeze which is unsqueezed by the anamorphic projector lens. Current anamorphic aperture for projection is just under 1.20 : 1, so when unsqueezed, the image is just under 2.40 : 1.

The two most common methods of getting a 2X anamorphic print are: (1) to shoot with 2X anamorphic camera lenses and contact print the negative; (2) to shoot with normal spherical lenses using a full aperture (Super-35) negative and compose for cropping to 2.40 : 1. The image is later cropped and stretched to a 2X anamorphic image and an anamorphic internegative is created, either digitally or optically. This is then contact printed.

35mm 1.85 or 1.66 widescreen is created during projection by use of a projector mask. The image is spherical.

Super-35 is not 1.85. Technically it is the same thing as Full Aperture photography, using the full width possible on the 35mm negative, from sprocket row to sprocket row, rather than leaving room for a soundtrack. If you are shooting 4-perf 35mm, then Super-35 is basically the same thing as the old Silent Era aperture, i.e. Full Aperture, which is 1.33 : 1. The only reason people think that Super-35 is a widescreen format is that the extra width is used to compose a wide image -- usually 2.40, but sometimes 1.85 -- ignoring the full height of the 4-perf negative.

If you shoot 3-perf Super-35/Full Aperture, the negative is 1.78 : 1. Again, usually you compose for cropping to 2.40 for making anamorphic prints, or for 1.85, which requires a step to shrink the image down slightly to the normal 1.85 projection area, which has room on the left for a soundtrack.

Super-35 is also used for shooting for TV transfer, either 4x3 (1.33) or 16x9 (1.78).
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#5 David Regan

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Posted 01 June 2007 - 11:35 PM

(2) to shoot with normal spherical lenses using a full aperture (Super-35) negative and compose for cropping to 2.40 : 1. The image is later cropped and stretched to a 2X anamorphic image and an anamorphic internegative is created, either digitally or optically. This is then contact printed.


Ok thanks a lot everyone this cleared up nearly all of my question. My final question in regards to your comment, David, is about the Super35mm, and using it to attain anamorphic. Firstly, if it was done this way, wouldn't the final result be distorted, because if it is shot with a normal spherical lens, it hasn't been squeezed, so by stretching it doesn't that make it look unnatural?
Also, this furthers my inital question regarding Super35mm, what exactly is the difference between Super and Standard? Is it a totally different negative stock, or simply framing with cropping in post?

Thanks
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#6 David Regan

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Posted 01 June 2007 - 11:39 PM

to shoot anamorphic you can shoot a full frame aperature with an anamorphic lens or shoot super 35 with a normal spherical lens. You would have to blow up the Super 35 print a little but negative is so good one can hardly notice. I believe shooting Super 35 one can do three frame pull down or a normal 4 frame. But you can frame for anamorphic cropping a little and losing a little negative area. One has the choice to shoot with the lens centered or use a common top header. One can also shoot techniscope which is an older 2 frame older pull down method.

http://www.panavisio...spect_ratio.php


Also
Tim thanks for your advice and the link. The link is good, I'm just wondering for clarity, what is the difference between aspect ratios that are listed as having the same ratio, but different frames, such as the two 2.40:1 ratios, "Anamorphic Projection Aperature" and "Super Panavision 35mm Extracted Area for Anamorphic Projection" They are listed as the same ratio but are different at the same time, same with the two 1.78:1 (16x9) at the bottom.

Thanks a lot

Edited by David Regan, 01 June 2007 - 11:40 PM.

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#7 Jon Kukla

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Posted 01 June 2007 - 11:41 PM

One is an anamorphic 2.40 ratio - 1.2 ratio with 2x squeeze, while the Super 35 is a spherical 2.40 and thus appears the same as the final image. Remember that Super 35 is only an origination format - it will be converted in post-production to an anamorphic print.

Edited by Jon Kukla, 01 June 2007 - 11:42 PM.

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#8 David Mullen ASC

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Posted 02 June 2007 - 12:00 AM

This is more accurate:
http://www.arri.de/i...ormat_guide.pdf

The Panavision drawings on that page are misleading. The anamorphic aperture should be offset to the right, as all the sound apertures are. The 2.40 area is extracted from the full 4-perf or 3-perf Full Aperture area for Super-35.

Here are some old charts I've made on some of these formats:

Posted Image

Posted Image
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#9 David Regan

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Posted 02 June 2007 - 12:21 AM

Great drawings/info thanks David, very helpful.
I think I got it now. Anamorphic can be achieve by either a) squeezing using an Anamorphic Lens and then unsqueezing when projected, or b)with Super35mm, which simply shoots over the area typically occupied by the audio track, allowing for a wider frame. The Anamorphic is then extracted (cropped) from this larger frame later attaining the 2.40:1 aspect ratio.

I guess its primarily about how you compose with future extraction/cropping in mind. Thank goodness for groundglass.

Unless I've mistaken some information I think I've got it.
Thanks everyone
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