If you are interested in the video quality of the Nikon D850 this short film by Tony Northrup may help you decide. He compares the D850 to the Sony a7Rii and the Panasonic GH5.
Nikon D850 Video Specs:
Movie – frame size (pixels) and frame rate
3840 x 2160 (4K UHD); 30p (progressive), 25p, 24p
1920 x 1080: 60p, 50p, 30p, 25p, 24p
1280 x 720: 60p, 50p
1920 x 1080 (slow-mo): 30p x4, 25p x4, 24p x5
Actual frame rates for 60p, 50p, 30p, 25p, and 24p are 59.94, 50, 29.97, 25, and 23.976 fps respectively; quality selection available at all sizes except 3840 x 2160 (when quality is fixed at “high”) and 1920 x 1080 slow-mo (when quality is fixed at “normal”)
Panasonic GH5 Video Specs:
The GH5 delivers Cinema 4K (4096×2160) video at 60p and 4K at 50p and uses the entire width of the sensor when shooting 4K before downsampling the footage in-camera. It has also got 4:2:0 8-bit internal recording, 4:2:2 10-bit internal at up to 30p, plus 4:2:2 10-bit external recording at 50p and 60p, which will give you much more chroma sub-sampling – this means more color grading capabilities. In fact, this is the color sub-sampling that’s commonly used for film and broadcast productions to aid more faithful color reproduction.
Sony a7R II Video Specs:
The Sony ?7R II camera include the ability to record movies in 4K quality (QFHD 3840×2160) in either Super 35mm crop mode or full-frame mode.
In Super 35mm mode, the camera collects a wealth of information from approximately 1.8x as many pixels as 4K by using full pixel readout without pixel binning and oversamples the information to produce 4K movies with minimal moire.
In full-frame mode, the a7RII utilizes the full width of the 35mm sensor for 4K recording, allowing users to utilize the expanded expressive power of the sensor. It is the world’s first digital camera to offer this in-camera full-frame format 4K recording capacity.
The camera utilizes the advanced XAVC S7 codec during video shooting, which records at a high bit rate of 100 Mbps during 4K recording and 50 Mbps during full HD shooting.
Additionally, the a7RII model features a variety of functions to support a professional video workflow including Picture Profile, S-Log2 Gamma and S-Gamut, 120fps high frame rate movie shooting in HD (720p), time code, clean HDMI output and more.
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