The Philosophy of 2.35:1 Constant Image Height Display – Part 1

Home theater has come such a long way since the days of VCRs and cathode ray tubes. Today it’s possible to watch movies in your own house approaching or even exceeding the quality of a commercial cinema. Yet for as many strides forward as home video technology has taken, almost the entire consumer electronics industry has gotten one fundamental concept wrong. What is the proper way to present 2.35:1 widescreen content on a television or projection screen?

A Quick History Lesson

Make no mistake, things are a lot better now than they used to be. Back in the VHS era, almost all movies were altered from their theatrical aspect ratios to fill the 4:3 televisions of the day. In a best case scenario, that might have only meant exposing extra headroom and footroom (and sometimes visible camera or microphone equipment) that viewers were not actually meant to see. On the other hand, it frequently meant cropping out almost half of a widescreen movie’s photography. Most people accepted that at the time because they simply didn’t know any better. The ability to watch a movie at home, any time you wanted and with no commercial interruptions, was so novel and exciting that pesky questions such as “Is that how it’s supposed to look?” weren’t given much thought.

For a Few Dollars More (1965) watched in pan & scan on a 4:3 TV

In the late 1980s and the 1990s, the niche Laserdisc video format attempted to address this issue through the process of letterboxing movies – that is, presenting a film’s widescreen photography in its correct shape by framing it on the screen with black bars above and below the picture. It was an innovative solution that fixed the problem of cropping, but at the expense of shrinking the image down to a smaller size on the screen. The grand epic scope of Ben-Hur was reduced to a rectangular strip half the height of The Price Is Right. Still, it was progress.

The Price Is Right (c. 1980s) full screen vs. Ben-Hur (1959) letterboxed on a CRT television

Laserdisc was a wonderful product in many respects, but it never gained much market traction and went mostly unnoticed by the public at large. At the tail end of the 1990s, DVD exploded onto the scene and ushered in a new home video renaissance. Among its other virtues, the format embraced the concept of Original Aspect Ratio right from the start and made letterboxing a standard feature. Although met with some resistance at first, this pushed the concept into the mainstream until, over time, most people came to accept it and stopped fretting about the black bars on their screens. The transition from boxy 4:3 CRT televisions to sexy new HDTV flat-panel displays with a wider, more cinematic 16:9 aspect ratio helped enormously. While letterboxing was still required for films with wider photographic ratios such as 2.35:1, the black bars were smaller and the movie image filled more of the screen. If still a compromise, it was tolerable enough to satisfy almost everyone, from novice viewers who just wanted to watch a big picture in their living rooms to cinema aficionados who demanded accuracy and authenticity in every movie’s film-to-video transfer.

Star Wars: The Empire Strikes Back (1980) letterboxed on a 16:9 television

In the couple decades since then, technology has continued to advance as DVD was followed by the superior video quality of Blu-ray and 4K Ultra HD, and physical media has largely given way to the convenience of internet streaming. However, through all this, 16:9 has stuck around as the default standard for almost all televisions and the vast majority of home theater projection screens. As a consequence, one very important idea has gotten lost.

2.35:1 Should Be Larger Than 16:9

Why do we even have more than one widescreen aspect ratio, anyway? Back in the 1950s, as the film industry struggled to compete with the widespread proliferation of televisions into nearly every home, Hollywood movie studios experimented with a number of new gimmicks to lure audiences back to theaters. Among others, these included innovations like stereo sound, 3D, and widescreen photography. The latter proved to be enormously successful, especially the CinemaScope format developed by 20th Century Fox.

As originally conceived, CinemaScope was explicitly designed to be projected onto screens the same height as the 1.37:1 “Academy Ratio” used throughout Hollywood’s Golden Age but twice as wide. The following famous promotional graphic is admittedly exaggerated for effect; the screen looks more like three times wider and has a dramatic curve. However, it gets the point across that CinemaScope was intended to be wider and more enveloping than the prior theatrical standard. In no way was it meant to be shorter.

CinemaScope screen size promotional graphic

Theaters of the day had to be retrofitted with larger screens to accommodate CinemaScope. Simply projecting a CinemaScope print at reduced size into the middle of an old screen would fail to convey the desired effect, and would in fact leave audiences questioning the point of making movies smaller than they’d been before. CinemaScope was about spectacle. Movies were bigger than ever! The best way to get viewers to leave their televisions was to give them an an experience they could not get at home.

CinemaScope premiered in 1953 with Fox’s biblical epic The Robe, projected at 2.55:1. A couple years later, the format’s aspect ratio was modified to 2.35:1 in order to add stereo soundtracks onto the film prints.

CinemaScope was sensationally popular and rapidly became the format of choice for historical epics, Westerns, musicals, and other lavish, big-budget extravaganzas. Audiences couldn’t get enough of the extra-large, extra-wide projected images, especially when utilized for sweeping landscape vistas or when populated with a so-called “cast of thousands” spread out across the wide ‘scope frame.

Because 20th Century Fox had proprietary ownership of the CinemaScope format and charged fees to use the process or rent its special anamorphic camera lenses, other movie studios rushed to develop their own competing widescreen formats at a variety of aspect ratios, such as 1.66:1 (VistaVision) and 2.20:1 (ToddAO 65mm). Most of those were short-lived until the industry settled on a dual theatrical standard that persists to this day. Movies photographed with spherical (“flat”) lenses would be projected at a ratio of 1.85:1 while those photographed with anamorphic lenses would be projected at 2.35:1.

Fox’s CinemaScope itself actually died off in the late 1960s and was supplanted by a very similar process developed by Panavision, which mimicked the same 2.35:1 aspect ratio but offered optically superior camera lenses. Panavision then revised that aspect ratio down to 2.39:1 in 1970 to fix an issue with unwanted flashing at the top of the frame. Technically speaking, the theatrical standard for anamorphic widescreen projection has been 2.39:1 for the past five decades, yet the terms “2.35:1” and “scope” are still commonly used for shorthand. I will do the same here, but know that – as mathematically illogical as it may be – the ratios 2.35:1, 2.39:1, and sometimes 2.40:1 all actually refer to the same thing and are frequently used interchangeably.

The 1.85:1 and 2.35:1 aspect ratios have both remained in active use ever since, carrying over to subsequent formats such as Super 35 and digital photography. For most of this time, one simple rule of presentation reigned: Regardless of how they were photographed, movies should ideally be displayed using the concept of Constant Image Height (CIH). Whether composed for 1.85:1 or 2.35:1, images should be projected onto the same screen with the same top and bottom frame lines, only varying by width. 2.35:1 is wider than 1.85:1, not shorter. Although not every theater followed this practice, the best premium venues did, often adding motorized curtains or masking panels to expand outward for the wider movies.

In accordance with this, filmmakers have significantly favored the scope 2.35:1 aspect ratio for big, expensive studio productions – your action movies, sci-fi, superhero epics, and other potential blockbusters – the type of movies that thrive on scale and spectacle, and demand to be seen on the largest screen possible. Think of any hugely popular, long-running movie franchise (Star Wars, Star Trek, Harry Potter, James Bond, Marvel, etc.) and odds are that most or all of its entries were shot at 2.35:1. Meanwhile, the narrower 1.85:1 ratio has often found use in comedies, intimate character dramas, and low-budget indie films.

Certainly, this is not an immutable rule that all movies must follow. Exceptions do exist, in both directions. Notably, Jurassic Park and Marvel’s The Avengers both used the narrower 1.85:1 ratio, while many comedies and even small art films have gone for the width of 2.35:1. Each film has its own artistic needs or aspirations that will determine the aspect ratio chosen, and some directors just feel more comfortable using one ratio rather than the other.

Nevertheless, if you look at the bigger picture (no pun intended) of Hollywood and world film production, the trend is undeniable. In recent years, the filmmaking community has leaned heavily toward the 2.35:1 aspect ratio above all others. In 2019 (the last year with a normal theatrical release schedule before the COVID-19 pandemic disrupted every studio’s distribution plans), over 70% of American theatrical films were composed for and distributed in 2.35:1 format.

American Theatrical Films by Aspect Ratio (2019)

This is especially true of studio tentpole movies with production budgets over $100 million, the overwhelming majority of which are photographed for 2.35:1. The biggest movies are far more often shot in scope.

So why are those same movies the smallest thing you’ll watch on your TV screen at home?

The Home Video Dilemma

When HDTV was first developed, the engineers and designers considered a number of possible screen aspect ratios. Filmmakers of the time argued for 2.35:1 screens to showcase their work at its best, while TV content producers (who weren’t all prepared to jump into high-def right away) wanted something closer to the 4:3 they’d been using. Also, shooting game shows or the local evening news in scope seemed unnecessary. Eventually, 1.78:1 (16:9) was chosen as a mid-point compromise, such that the presumed widest content likely to be watched on the screen and the narrowest would have approximately the same amount of black bars. 16:9 was never meant to be any sort of aesthetic ideal screen ratio. It was merely the most convenient. The fact that it was pretty close to the 1.85:1 theatrical format lent it a feeling of legitimacy, as if it weren’t an entirely arbitrary number.

This was good enough for most people. Indeed, 16:9 is a very good aspect ratio for an average living room television. A 2.35:1 screen would be fairly impractical at screen sizes 36″ or less, viewed from a couch fifteen feet across the room. In that use case, 16:9 makes plenty of sense.

But this isn’t an article about that sort of casual viewing scenario. We’re talking about home theater here – the mindful attempt to recreate a cinematic experience in the home, with a big screen and a good audio system. In that regard, 16:9 screens have a very serious limitation. No matter how large a TV or projection screen you install, scope 2.35:1 content will unavoidably be the smallest thing viewed on it. Jaws will always be smaller than Dancing with the Stars. This falls in direct opposition to the artistic intent of the format.

Philips Cinema 21:9 TV (c. 2011)

For a brief time, some manufacturers attempted to cater to a cinephile audience by making televisions with wider screens. Philips marketed this as “Cinema 21:9.” Sadly, it didn’t catch on. For the last couple decades since HDTV went mainstream, an idea has been drilled into most consumers’ heads that 16:9 is the one and only correct aspect ratio for a television screen. Anything else looks strange to them. On top of that, 2.35:1 is still admittedly not always practical for a flat-panel display. Ideally, a Constant Image Height screen should not compromise the desired size of 16:9 imagery at all. CIH should be executed by starting with as large a 16:9 picture as you’d want, and then adding width. When dealing with a 16:9 center area of 65″ or larger, extending the width of that can leave you with a very unwieldy box that may be difficult if not impossible to get into a home or mount on a wall.

Although 21:9 has gained more traction in the computer monitor sector (I’m writing this article on one right now!), those screens are smaller and not especially useful for home theater unless you sit very close to them.

Projectors Lead the Way

The story is very different once you move into the world of home theater projectors. A projection screen can be much larger than a flat-panel TV, yet will easily fit through your door and maneuver around corners when rolled up for delivery. Projectors also make Constant Image Height far more feasible.

The Constant Image Height screen in the Cinema Zyberdiso

In its simplest application, Constant Image Height only requires a screen of the appropriate 2.35:1 aspect ratio (2.39:1 or 2.40:1 if you’re a stickler) and a projector with enough optical zoom range to fill the top and bottom of the frame with a movie’s active image at either 16:9 or 2.35:1 aspect ratios. More details on this, as well as alternate display methods, will be discussed in our Best Practices for 2.35:1 Constant Image Height article later.

In times past, some home theater users worried that zooming up a scope picture to a larger size than 16:9 could result in poorer image quality, due to the fact that home media uses fewer pixels in a letterboxed picture than a full-screen picture (some being wasted on the letterbox bars). That may have been true with standard-def sources like DVD, but HD and especially 4K Ultra HD have more than enough resolution to make this concern irrelevant. 1080p and 4K hold up very well even on the largest home theater screen sizes.

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