Een artikel van de Red-user, van het Net geplukt:  What is 4K?


Digital Cinema

Unlike film, digital cinema is not working against grain. Because the image is clean from square one, 4K appears significantly sharper than a 4K film scan would. Any description would be biased, so I'll simply post the images.

One must consider that this 2K image is essentially 4x over-sampled. Super 16mm area 2K will not be over-sampled and should exhibit similar qualities to the image below.

That said, these essentially speak for themselves. The images are free of any noise or grain of any kind. The detail in the 4K image is vastly superior to the detail of the S16mm 2K scan above [4K S35mm equivalent].


Formats

While Mysterium‚Ñ¢ has an active pixel array of 4,520 x 2,540, not all formats are created equal. Part of the beauty of the RED ONE is that it can capture so many different formats on the same sensor. Here are the available formats:

Super 35mm sensor area
2540p
24.4mm x 13.7mm

35mm sensor area
4K
22.2mm x 12.6mm

Super 16mm sensor area
2K
11.1mm x 6.3mm

2/3" B4 sensor area
1080p
10.4mm x 5.9mm


Many people confuse the S35mm and 35mm motion picture formats with the full frame 35mm still format. The full frame 35mm still format is 36.0mm x 24.0mm - very similar to the VistaVision motion picture format. Nearly every motion picture shot today is filmed using the 35mm or S35mm area of the negative. For a visual comparison between all formats relative to RED discussion, see the image below.

Be sure to note that the "Arri Standard 35mm" area is not on the centerline of the diagram, so its size relative to the other formats cannot be inferred using the provided vertical guides. That said, it is obviously narrower than any other relevant format - just don't use the provided vertical guides to assess how narrow it is.
The noise/lines left of the Arri Standard 35mm format represent audio tracks and references on a standard film print.

In addition to the aforementioned formats, I have also included Canon's 1.6 crop digital SLR format and Nikon's 35mm digital SLR format. The Canon and Nikon digital SLR formats are very similar to the 35mm format imaged by Mysterium‚Ñ¢. Different formats all have different field of view and depth of field characteristics. For discussions on these subjects, see the appropriate sections below.

One key thing to note here is that RED's 4K sensor area [the area that they describe as "35mm" instead of "Super 35mm"] is only marginally different than Arri's Super 35mm area. RED's "Super 35mm" 4.5K sensor area is actually larger than Arri's Super 35mm area. You can clearly see that RED's definition of "35mm" as it relates to the 4K sensor area is vastly different than "Standard 35mm" or "Academy 35mm" that we're all used to. RED's 4K "35mm" sensor area is, for all intents and purposes, nearly equivalent to film's Super 35mm format size.

Mysterium‚Ñ¢ captures the smaller formats by "cropping" its sensor area. For example, if one were to shoot 2K utilizing the S16mm sensor area, only that area of the sensor would be active. The outer area of the sensor [the S35mm area where a S16mm lens would not resolve] is ignored. This is what is meant by describing a format as "cropped". Shooting 2K cropped is the same as shooting S16mm 2K.
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Robert M. Berger