Random Thoughts – Randocity!

What is 35mm film resolution?

Posted in entertainment, film, movies, technologies by commorancy on December 26, 2018

filmstrip-fI’ve seen a number of questions on Quora asking about this topic, likely related to 4K TV resolution. Let’s explore.

Film vs Digital

What is the amount of pixels in a 35mm frame of film? There’s not an exact number of pixels in a single frame of 35mm film stock. You know, that old plasticky stuff you had to develop with chemicals? Yeah, that stuff. However, the number of pixels can be estimated based on the ISO used.

Based on an ISO of 100-200, it is estimated that just shy of 20,000,000 (20 million) pixels make up a single 35mm frame after conversion to digital pixels. When the ISO is increased to allow more light into the aperture, this increases film noise or grain. As grain increases, resolution decreases. At an ISO of 6400, for example, the effective resolution in pixels might drop to less than 10,000,000 (10 million) due to more film grain. It can be even lower than that depending on the type of scene, the brightness of the scene and the various other film factors… including how the film was developed.

If we’re talking about 70mm film stock, then we’re talking about double the effective resolution. This means that a single frame of 70mm film stock would contain (again at ISO 100-200) about 40,000,000 (40 million) digital pixels.

Digital Cinematography

Panavision Millenium DXL2With the advent of digital cinematography, filmmakers can choose from the older Panavision film cameras or they can choose between Panavision‘s or RED‘s digital cameras (and, of course, others). For a filmmaker choosing a digital camera over a film camera, you should understand the important differences in your final film product.

As of this article, RED and Panavision digital cinematography cameras produce a resolution up to 8k (7,680 × 4,320 = 33,177,600 total pixels). While 33 million pixels is greater than the 20 million pixels in 35mm film, it is still less resolution than can be had in 70mm film at 40 million pixels. Red DragonThis means that while digital photography might offer a smoother look than film, it doesn’t necessarily offer better ‘quality’ than film.

Though, using digital cameras to create content is somewhat cheaper because there’s no need to send the footage to a lab to be developed… only to find that the film was defective, scratched or in some way problematic. This means that digital photography is a bit more foolproof as you can immediately preview the filmed product and determine if it needs to be reshot in only a few minutes. With film, you don’t know what you have until it’s developed, which could be a day or two later.

With that said, film’s resolution is based on its inherent film structure. Film resolution can also be higher than that of digital cameras. Film also looks different due to the way the film operates with sprockets and “flipping” in both the camera and projector. Film playback simply has a different look and feel than digital playback.

RED expects to increase its camera resolution to 10k (or higher) in the future. I’m unsure what exact resolution that will entail, but the current UW10k resolution features 10,240 × 4,320 = 44,236,800 pixels. This number of pixels is similar to 70mm film stock in total resolution, but the aspect ratio is not that of a film screen, which typically uses 2.35:1 (Cinemascope widescreen) or 16:9 (TV widescreen) formats. I’d expect that whatever resolution / aspect that RED chooses will still provide a 2.35:1 format and other formats, though it might even support that oddball UW10k aspect with its 10,240 pixels wide view. These new even wider screens are becoming popular, particularly with computers and gaming.

Film Distribution

Even though films created on RED cameras may offer an up to 8k resolution, these films are always down-sampled for both theatrical performance and for home purchasing. For example, the highest resolution you can buy at home is the UltraHD 4K version which offers 3,840 x 2,160 = 8,294,400 pixels. Converting an 8k film into 4k, you lose around 24 million pixels of resolution information from the original film source. This is the same when converting film stock to digital formats.

Digital films projected in theaters typically use theatrical 4K copies, much the same as you can buy on UltraHD 4K discs, just tied to a different licensing system that only theaters use.

Future TV formats

TV resolutions have been going up and up. From 480p to 1080p to 4K and next to 8K. Once we get to 8K in the home, this is the resolution you’ll find natively with most digitally captured films. Though, some early digital films were filmed in 4K. Eventually, we will be able to see digital films in its native resolution. 8K TVs will finally allow home consumers to watch films in their filmed resolution, including both 35mm film and 70mm film stock both as well as many digital only films.

For this reason, I’m anxious to finally see 8K TVs drop in price to what 4K TVs are today (sub $1000). By that time, of course, 4K TVs will be sub $200.

8K Film Distribution

To distribute 8K films to home consumers, we’re likely going to need a new format. UltraHD Blu-ray is likely not big enough to handle the size of the files of 8K films. We’ll either need digital download distribution or we’ll need a brand new, much larger Blu-ray disc. Or, the movie will need to be shipped on two discs in two parts… I always hated switching discs in the middle of a movie. Of course, streaming from services like Netflix is always an option, but even 4K isn’t widely adopted on these streaming platforms as yet.

Seeing in 8K?

Some people claim you can’t see the difference between 1080p and 4K. This is actually an untrue statement. 1080p resolution, particularly on a 55″ or larger TV, is easy to spot the pixels from a distance… well, not exactly the pixels themselves, but the rows and columns of pixels (pixel grid) that make up the screen. With 4K resolution, the pixels are so much smaller, it’s almost impossible to see this grid unless you are within inches of the screen. This makes viewing films in 4K much more enjoyable.

With 8K films, the filmed actors and environments will be so stunningly detailed as to be astounding. We’ll finally get to see all of that detail that gets lost when films are down-converted to 4K from 8K. We’ll also get to see pretty much what came out of the camera rather than being re-encoded.

Can humans see 8K? Sure, just like you can see the difference between 1080p and 4K, you will be able to see a difference in quality and detail between 4K and 8K. It might be a subtle difference, but it will be there and people will be able to see it. Perhaps not everyone will notice it or care enough to notice, but it will be there.

Film vs Digital Differences

The difference between film and digital photography is in how the light is captured and stored. For film, the camera exposes the film to light which is then developed to show what was captured. With digital photography, CMOS (Complimentary Metal Oxide Semiconductor) or possibly CCDs (Charge Coupled Devices) are used to capture imagery. Most cameras today opt for CMOS sensors because they’re less expensive to buy and provide equivalent quality to the CCD sensors. For this reason, this is why RED has chosen CMOS as the sensor technology of choice for their cameras. Though, RED cameras are in no way inexpensive, starting at around $20k and going up from there.

Overall

In concluding this article, I will say that 4K is definitely sufficient for most movie watching needs today. However, Internet speeds will need to improve substantially to offer the best 8K viewing experience when streaming. Even Netflix and Amazon don’t currently provide even an amazing 4K experience as yet. In fact, Netflix’s 4K offerings are few and far between. When you do find a film in 4K, it takes forever for Netflix to begin streaming this 4K content to the TV. Netflix first starts out streaming at 480p (or less), then gradually increases the stream rate until the movie is finally running at 4K. It can take between 5-10 minutes before you actually get a 2160p picture. Even then, the resolution can drop back down in the middle and take minutes before it resumes 4K.

Today, 4K streaming is still more or less haphazard and doesn’t work that well. That’s partly due to Netflix and partly due to the Internet. The streaming rate at which 4K content requires to achieve a consistent quality picture can really only be had from Blu-ray players or by downloading the content to your computer in advance and playing it from your hard drive. Streaming services offering 4K content still have many hurdles to overcome to produce high quality consistent 4K viewing experiences.

For this reason, 8K streaming content is still many, many years away. Considering that 4K barely works today, 8K isn’t likely to work at all without much faster Internet speeds to the home.

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