Anamorphic lenses and full frame imaging; the maths and science involved, and how it impacts aspect…
Anamorphic and Cinemascope are loosely used to be synonyms at times. My effort here is to make better sense of these concepts in the context of the new age digital cinematography. The approach is to explain what each of these terms mean and the maths involved, so that the differences if any, will show up on their own.
As cinematographers, we use two types of lenses, the spherical and the anamorphic lenses. Every lens unit is made up of various optical elements which are individual pieces of lenses arranged in a tubular housing. All lenses used for imaging purposes are essentially spherical in nature, which bends the light rays entering the lens in an equal proportion on both the vertical and horizontal axes.
The result therefore is the formation of a circular image area. The spherical lens, just as the name suggests uses spherical elements to capture an image. As explained below, these lenses project images onto the sensor or the film stock without affecting their proportionality. So if we were to see how the image is captured on the imaging plane, it’s how we see is what we get.
On the other hand, Anamorphic essentially means an intended distortion. The word anamorphic and its derivatives stem from the Greek anamorphoun (to transform), compound of morphé (form, shape) with the prefix aná (back, against). The anamorphic format involves stretching an image optically, by using cylindrical elements inside a lens, so as to fit it into a narrower imaging area. Lens manufacturers use an additional section of cylindrical elements within the housing along with the standard spherical elements. Anamorphic lenses, create a version of the image that is compressed along the longer dimension (usually by a factor ranging from 1.3 to 2.0). We shall talk about the compression factor later on but first let’s understand why filmmakers needed to use compression at all.
Why Anamorphic?:
During celluloid days, the objective of shooting anamorphic was to be able to use of a larger area on the film negative with a widescreen aspect ratio. This would reduce film grain and imaging area will be more than using spherical lenses. Remember the standard of projection used to be 4:3 or 1:1.33 which was more of a squarish than a wide rectangular format which have become a standard in today’s times. So, on film stock if u had to
How to project an image shot on anamorphic lens?:
No points for guessing that if the image that has been captured is squeezed, then the final projection cannot be the same, hence it has to be de-squeezed back to its original form in the post production process before the final projection. Looks like a lot of work, but as long as it is all worth the pain.
widescreen movies to enable the use of a larger area on the film negative to reduce film grain.
Most anamorphic lenses squeeze the image by a factor of two, but there are also lenses with other squeeze
factors. In order to provide a properly proportioned image to on-set monitoring, ALEXA cameras can “desqueeze”
the image for the electronic viewfinder and monitor outputs.
History of Anamorphic:
So what was the CinemaScope again?
When the patents for the anamorphic process had already run out by 1952, Twentieth Century Fox trademarked the term ‘CinemaScope’. In the beginning, they were also the only ones in possession of anamorphic lenses. Widescreen and Cinemascope became synonymous to the audience and films that wanted to use their lenses and the CinemaScope trademark, had to pay up a lot towards licensing fees. This led to the development of other anamorphic lenses and a number of competing widescreen processes, some anamorphic and some spherical, some using 35mm film and some larger gauges. These competing processes were given more or less creative names such as Scanoscope, SuperScope, Techniscope, Arnoldscope, Vistarama or Thrillarama. So technically CinemaScope is a Fox trademark rather than a description for the anamorphic process, even though they are often used interchangeably.
Aspect Ratios:
Up until 1952, cinema formats were easy to understand as all mainstream movies and television productions
were shot and projected in the aspect ratio of 4:3 (1.33:1). When anamorphic shooting became popular after
1952, a number of aspect ratios were experimented with for anamorphic productions, including 2.66:1 and
2.55:1. The need for reducing costs even further subsequently spawned the spherical widescreen formats of
1.85:1 and 1.66:1. A SMPTE specification for anamorphic projection from 1957 (PH22.106–1957) finally
standardized the aperture to 2.35:1. An update in 1970 (PH22.106–1971) changed the aspect ratio to 2.39:1
in order to make splices less noticeable. This aspect ratio of 2.39:1 was confirmed by the most recent
revision from August 1993 (SMPTE 195–1993).
Unfortunately, everyone was so used to calling anamorphic films 2.35:1, that many still use that aspect ratio
erroneously, even when talking about films shot after 1970. Similarly, 2.40:1 is an incorrect, unfortunate and
unnecessary rounding up; a proper rounding up would be 2.4:1. The correct aspect ratio for anamorphic
films shot after 1970 is 2.39:1.
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