Jump to content


Photo

Squeeze


  • Please log in to reply
11 replies to this topic

#1 Spencer Hutchins

Spencer Hutchins
  • Basic Members
  • PipPip
  • 59 posts
  • Cinematographer
  • Los Angeles, CA

Posted 05 February 2009 - 01:43 PM

For some reason I can't quite wrap my head around the 'squeezing' of images while shooting, and how that relates to the final 'unsqueezed' image we see after post.

Anything on the subject would be appreciated!
  • 0

#2 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19759 posts
  • Cinematographer
  • Los Angeles

Posted 05 February 2009 - 01:46 PM

For some reason I can't quite wrap my head around the 'squeezing' of images while shooting, and how that relates to the final 'unsqueezed' image we see after post.

Anything on the subject would be appreciated!


Are you asking about anamorphic lens photography (optical squeezing) or 16x9 "anamorphic" SD video, or general use of non-square pixels in some recording formats?
  • 0

#3 Spencer Hutchins

Spencer Hutchins
  • Basic Members
  • PipPip
  • 59 posts
  • Cinematographer
  • Los Angeles, CA

Posted 05 February 2009 - 01:57 PM

A lot of that is foreign to me, so I guess in general..all of it :)
  • 0

#4 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19759 posts
  • Cinematographer
  • Los Angeles

Posted 05 February 2009 - 02:07 PM

Have you ever put a wide-angle adaptor on the front of a camera lens? An anamorphic lens is similar in principle except that it only increases the field of view in the horizontal direction, not vertically, and then squeezes that wider view onto the same area. Sort of like a funhouse mirror that makes everyone look skinnier. In fact, some anamorphic lenses actually do involve the use of a front-surface mirror on a curved cylindrical surface to do the squeezing (the old Delrama lenses used for Technirama).

This allows you to fit a wider-screen image onto a squarer surface area, whether a squarer sensor or film format.

But obviously you're not meant to see a skinny-looking image in the final presentation so it has to be stretched out again horizontally to look normal and thus wider.

In 35mm filmmaking, the anamorphic camera lenses commonly have a 2X horizontal squeeze and the anamorphic projector lenses have a 2X horizontal unsqueeze or stretch. So the printed image becomes twice as wide on the screen as it is on the print itself.

So if the final projected image becomes 2.40 : 1, that means the projector is using a 1.20 : 1 gate, but the 1.20 : 1 image on the print itself has a 2X squeeze to it.

This is why there is talk of making 1.33X or 1.34X anamorphic lenses so you can squeeze a 2.40 image onto something less square than a 4-perf 35mm 4x3 negative, like onto a 16x9 sensor or a 3-perf 35mm negative, or a Super-16 negative. On those wider-shaped formats, a 2X squeeze is too much so you need an anamorphic lens with a milder squeeze factor.
  • 0

#5 Spencer Hutchins

Spencer Hutchins
  • Basic Members
  • PipPip
  • 59 posts
  • Cinematographer
  • Los Angeles, CA

Posted 05 February 2009 - 06:30 PM

So if the final projected image becomes 2.40 : 1, that means the projector is using a 1.20 : 1 gate, but the 1.20 : 1 image on the print itself has a 2X squeeze to it.


Most of this matches how I 'assumed' it worked, but still cannot quite comprehend how the projector accomplishes this 'de-squeeze' I guess. I understand that it works, but just have a hard time understanding how it works.

Thank you once again David. :)
  • 0

#6 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 05 February 2009 - 08:00 PM

Most of this matches how I 'assumed' it worked, but still cannot quite comprehend how the projector accomplishes this 'de-squeeze' I guess. I understand that it works, but just have a hard time understanding how it works.

Thank you once again David. :)


It gets unsqueezed exactly the same way it gets squeezed. On the camera there is a cylindrical element that make the picture squarer and makes people tall and skinny.

On the projector lens, there is an element that is the negative of the one on the camera. It optically stretches it back out to the proper proportions.
  • 0

#7 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19759 posts
  • Cinematographer
  • Los Angeles

Posted 05 February 2009 - 08:46 PM

Take a look:
http://www.panamorph...Technology.html
http://www.zuggsoft....eater/prism.htm
  • 0

#8 Spencer Hutchins

Spencer Hutchins
  • Basic Members
  • PipPip
  • 59 posts
  • Cinematographer
  • Los Angeles, CA

Posted 05 February 2009 - 10:16 PM

It gets unsqueezed exactly the same way it gets squeezed.


Indeed it does Chris, I believe I understand that much better now.

Take a look:
http://www.panamorph...Technology.html


This link was very helpful in the explanation of how anamorphic images can be created by both horizontal expansion and vertical compression.

So as I understand it, Cylindrical Pair Anamorphic Lenses are used to horizontally stretch the image, whereas Prism Pair Anamorphic Lenses are used to do the vertical compressing of images. Now the horizontal stretch of the Cylindrical Pair Lenses make sense to me, but I still do not see how the vertical compression of the Prism Pair Lenses work. Since this process is not gaining any horizontal view, is the entire image somehow magnified to fit the 2.35:1 format? If so, doesn't this reduce the quality of the image drastically?

Also, if the Panamorph Lenses are using optics from both of these other optic systems (Cylindrical Pair/ Prism Pair) what then are these lenses actually doing..the horizontal stretch or the vertical compression, or both?

Have either of you used these Panamorph Lenses before?

Thank you both again gentlemen. :)
  • 0

#9 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19759 posts
  • Cinematographer
  • Los Angeles

Posted 05 February 2009 - 10:34 PM

Those links were in regards to projector lenses but I just was looking for some drawings of the anamorphic principle for you.
  • 0

#10 Spencer Hutchins

Spencer Hutchins
  • Basic Members
  • PipPip
  • 59 posts
  • Cinematographer
  • Los Angeles, CA

Posted 05 February 2009 - 10:44 PM

Oh I see, understood. Looking forward to the drawings!
  • 0

#11 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 06 February 2009 - 01:05 AM

Also, if the Panamorph Lenses are using optics from both of these other optic systems (Cylindrical Pair/ Prism Pair) what then are these lenses actually doing..the horizontal stretch or the vertical compression, or both?


In the end, it doesn't really matter whether the image is squeezed horizontally or stretched vertically. The magnification of the image could be changed to get the same results. I don't have any optical plans for modern anamorphic lenses, but chances are, most anamorphic lenses today use a combination of methods to aid in minimizing unwanted distortions.

Edited by Chris Keth, 06 February 2009 - 01:05 AM.

  • 0

#12 Spencer Hutchins

Spencer Hutchins
  • Basic Members
  • PipPip
  • 59 posts
  • Cinematographer
  • Los Angeles, CA

Posted 06 February 2009 - 09:41 AM

No plans for modern anamorphic lenses?! I expected more from you Chris! ;)

I realize that aberrations, distortion and lateral chromatic aberrations vary (as far as presence) in between the two, but as far as quality in the 'de-squeezing' stages the quality lost would be the same whether you used horizontal or the vertical options?

Thanks again Chris :)
  • 0


Paralinx LLC

Media Blackout - Custom Cables and AKS

Glidecam

Opal

Metropolis Post

Willys Widgets

Tai Audio

Visual Products

The Slider

CineTape

Aerial Filmworks

FJS International, LLC

CineLab

Abel Cine

Ritter Battery

Broadcast Solutions Inc

rebotnix Technologies

Wooden Camera

Technodolly

Rig Wheels Passport

Gamma Ray Digital Inc

FJS International, LLC

Gamma Ray Digital Inc

The Slider

Opal

Glidecam

Visual Products

Technodolly

CineLab

CineTape

Broadcast Solutions Inc

Abel Cine

rebotnix Technologies

Metropolis Post

Willys Widgets

Rig Wheels Passport

Ritter Battery

Wooden Camera

Media Blackout - Custom Cables and AKS

Aerial Filmworks

Tai Audio

Paralinx LLC