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   2014 = 4K

4K resolution is not new in the cinema industry, but this year is the year of 4K because of the introduction of new consumer grade cameras designed for 1080P as well as for 4k recording.

The first camera announced this year was the Panasonic GH4, a killer camera you can buy for the same price of the previous GH3 model. It can record true 4K video IN CAMERA on SD cards (albeit in 4:2:0).

Then Sony replied with an Alpha 7s model, with a new 12megapixel 24X36 sensor which can output "4K" (Quad FHD) without pixel binning to an external recorder (1080p internally).

Why 4K? Do you need it? Do we need it?
4K is useful only for heavy post production tasks , i.e. grading (4K 4:2:0 can be downsampled to 2K/1080 4:4:4), cropping, adding digital effects and stabilizing. Very few cinemas in the world do use 4K projectors, the vast majority uses 2K, and at home you can hardly tell the difference between PAL DVD resolution and FullHD/1080 (if you sit at a regular distance from the screen), let alone 4K.

We are nevertheless living in an exciting era. We will see soon what 4K video available to everybody will offer us in term of new creative solutions and implementations.

These are the infos we have so far regarding the 4K features on these cameras:

  GH4 A7s
Pixel binning NO NO
Line skipping NO NO
Downsampling NO* YES**
In camera 4K recording YES (4:2:0) NO
Cinema 4K YES (24p only) NO

* it means slight crop of the sensor (approximately 500 horizontal pixels) for 4K
** it can be an advantage here since you want to use a 24X36mm camera with full 35mm lenses on the full frame for DOF rendition. Downsampling always means cropping if the sensor resolution doesn't match exactly the 8 megapixels required for 4K.
Both cameras have clean HDMI output so can record 4:2:2 4K on an external recorder

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