Film-Term Glossary: Understanding the Differences Between 2K, 4K, 35mm, 70mm and More

Film-Term Glossary: Understanding the Differences Between 2K, 4K, 35mm, 70mm and More

Sep 04, 2012

What's the difference between 35mm and 70mm film? What about 2K vs. 4K resolution? Where does IMAX fit in the equation? These are the kinds of questions that, regardless of how much you love film, you might not know the answer to. Which is why we've put together this handy, easily digestible glossary explaining some of the more technical aspects of both film production and exhibition, and what kind of a difference they might make on the way you watch movies.



What is it: A digital cinema standard. A film with a 1.85:1 aspect ratio has a resolution of 1998x1080; a 2.35:1 AR is 2048x858.

What difference does it make: As of right now, 2K is essentially the standard for digital projection in cinemas. Though they use different standards, it's not far off to think of 2K as the theatrical equivalent of a 1080p HDTV, only at a slightly higher resolution.



What is it: A digital cinema standard. A film with a 1.85:1 aspect ratio has a resolution of 3996x2160; a 2.35:1 is 4096x1716.

What difference does it make: Increased picture quality. As the higher number implies, this is the big brother of 2K presentation. It, however, is not currently the digital projection standard and whether or not a theater uses it is contingent on their equipment. The cleaner, sharper image that 4K projectors allow for is, however, becoming the new norm for theatrical exhibition. When you hear of an old film getting a special theatrical run once again (even if for one night), hopefully it's a 4K remaster, as that's the best presentation you're going to find of a movie that hasn't been in theaters for years.


Digitally Remastered

What is it: The process of transferring a film from one format (say 35mm) to a new one (say Blu-ray).

What difference does it make: Often when a new DVD or Blu-ray for a catalog film comes out, a studio will boast of having digitally remastered the film. This doesn't mean that they've gone through George Lucas-style and added digital elements where there were none prior, it's simply the process of taking older film elements and using them as the source material for a new image transfer. What this process actually entails can vary from film to film, but it typically involves a studio gathering the most pristine film elements they can find (sometimes going back to the original film negatives it was shot on), digitally scanning them frame by frame and augmenting the image where necessary.

For a good understanding of the kind of undertaking remastering a film can be, check out this video chronicling the restoration of Jaws for Blu-ray.



What is it: The most common film size used in photochemical motion pictures.

What difference does it make: From a filmmaking standpoint, 35mm is, by today's digital standards, the old-school way of making movies. It involves shooting on actual spools of film, a limitation that forces 35mm filmmakers to rehearse and find creative compromise lest they run out of film to shoot on.

From an exhibition standpoint, 35mm is, also by today's digital standards, the old-school way of showing movies. Everything about it is a more physical process, meaning that prints of films will show signs of age the more they're shown, giving a popular, heavily screened film the type of scratches and burn marks that many who want to emulate the "film look" fake digitally these days. As far as resolution is concerned, 35mm has approximately the resolution equivalent of 4K, if not higher. Basically, ideal 35mm presentation is even better than ideal digital presentation.

However, because film prints weigh considerably more than the Digital Cinema Packages (DCP) sent out to theaters that use digital projectors, studios are pushing away from 35mm. A studio can send out thousands of DCPs for a new release for a fraction of the cost of sending film prints, a savings that is further driving studios away from 35mm all together. Though it's worth noting that some experts debate the long-term savings. When it comes to preserving a movie, a studio can simply stick 35mm film into a climate-controlled vault and it'll be there ready to use in 100 years. Digital files, however, need to be stored on harddrives, which are much more prone to failure and human error, not to mention a need to keep up with new codec and connection standards, thus increasing the costs of preservation over time.



What is it: A high-resolution, larger aspect ratio film format that is becoming increasingly endangered. Before diving into the explanation, it's important to note that 70mm is an umbrella term. The actual size of the film that goes into various 70mm cameras and projectors varies.

What difference does it make: From a filmmaking standpoint, 70mm is the hardcore older brother of 35mm. It's twice the size, allowing for considerably larger resolution and aspect ratios, resulting in a wider display field. As far as film goes, 70mm is as good as it gets. 

From an exhibition standpoint, 70mm is an increasingly abandoned format. Few productions are shot natively on 70mm film (though there are still a few notable ones, most recent examples being select portions of The Dark Knight Rises and the entirety of The Master), meaning even fewer theaters have the capability of showing films that way. It's what IMAX film and theaters use, though it's not exclusive to their cameras or projectors (IMAX is actually a taller aspect ratio than standard 70mm). 




What is it: A larger-than-normal film and projection standard created by the IMAX Corporation.

What difference does it make: The IMAX Corporation has spun off its technology into several permutations in the decades since its introduction in the mid 1960s, but there is a core principal they all share: bigger is better. An IMAX theater is defined by its larger screens and speakers. Likewise, IMAX film is defined by its larger format, which is twice the size of standard film. In its ideal state, IMAX film projected in an IMAX theater is the highest resolution spread across the largest movie theater screens in the world, which also happen to boast a larger surround sound experience as well, with speakers not only directly behind the screen, but placed above it as well to counter the increased height of the screen.

However, there is a very important distinction to make between traditional IMAX and IMAX Digital. In 2008, IMAX struck up contracts with theaters around the world to retrofit existing rooms with IMAX-branded equipment. However, this meant simply installing custom projectors -- a system that projects two 2K images on top of each other, resulting in a brighter image, but not a higher resolution one. This is a vastly inferior resolution compared to IMAX films', and as such has been dubbed by purists as LieMAX. Still, an IMAX digital presentation is preferable to a 2K presentation, though not necessarily 4K.


RED cinema logo


What is it: A digital camera company that is fast becoming synonymous with professional-grade digital filmmaking.

What difference does it make: The difference between films shot on RED cameras versus other digital cameras is almost entirely down to personal preference. However, because RED cameras are becoming such buzzwords in Hollywood (The Girl with the Dragon Tattoo, Prometheus and The Hobbit were all shot on RED, just to name a few), we felt its inclusion in the glossary was necessary. Basically, RED makes affordable (by industry standards, not consumer standards), high-quality, constantly-evolving digital cameras (they were one of the first to make professionally accepted cameras capable of 4K). Think of them as the digital generation's Kodak-- they're not the only game in town, but they're becoming the poster child for the medium.

High Frame Rate (aka 48 fps or higher)

What is it: The frame rate refers to the frequency with which individual images are captured/projected per second. The industry standard is 24 fps.

What difference does it make: Film is essentially nothing more than single images projected in rapid succession, the norm being 24 images per second. If, as Peter Jackson is doing on his The Hobbit trilogy, one doubles the fps, one doubles the amount of visual information processed, either by the camera during filming or by the brain during projection. As a result camera movement becomes clearer as less visual information is lost in the capture process, eliminating the strobing effect that can happen with 24 fps material. However, this smoother, more real-world look is at odds with the 24-fps-constrained look that people have associated with films for decades. Several key players in the film industry are pushing for higher frame rates, but only time will tell if the overtly slick aesthetic will catch on with audiences.

For further reading, has a very elaborate breakdown of various frame rates, with plenty of examples of the difference they can make.


Dolby Atmos

What is it: A new surround sound technology from audio pioneers Dolby Laboratories.

What difference does it make: Dolby Atmos is surround sound on steroids. Traditional surround sound systems do just that; they surround the listener like a circle, with audio passing from the front to the side and then to the rear. Dolby Atmos takes that circle and turns it into a bubble, allowing for up to 128 discrete sound tracks and 64 different speaker feeds not only on the sound plane around you, but above and below you. The result is a considerably more precise sound field that allows, for example, for speakers directly over your head to play a different sound of rain falling downward than the speakers to your side, which can then pickup what the droplets sound like at ear level and so on. There are only 25 theaters being upgraded with Dolby Atmos so far in 2012, but the company hopes to keep expanding in years to come.


What is it: A movie theater that combines a 3D image on the screen with extra gimmicks in the theater, like moving seats, misters that spray water into the air, and even smell-o-vision.

What difference does it make: It really just depends on how many gimmicks you can take. Filmmakers aren't exactly tailor-making their films for 4D exhibition, so all of the extra bells and whistles are all designed by the theater company. How much they immerse you in the film is up to you.

Follow along on Twitter: @PeterSHall and @Moviesdotcom.

Categories: Features, In Theaters, At Home, Geek
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