What is a Bayer filter?

A bayer filter is a colour filter array in a checkerboard pattern that is placed over a single chip ccd or cmos imager to create a colour image. 50% of the pixels are filtered green, 25% red, and 25% blue.  Averaged together, a Bayer chip misses up to 67% of the color information in the image. This isn't as bad as it sounds. Complex calculations from surrounding pixels are made to interpolate the missing colors at each pixel.  However the actual detail is more difficult to "guess" and can result in artefacts or softness. 

Bayer pattern color cameras do not produce equivalent resolution to 3 chip sensors.

So a 4k or 2k Bayer chip may have 3k and 1.5k resolution respectively. This puts the resolution similar to or better than 1920x1080 4:2:2 or 4:4:4 recording. Careful testing of the new cameras should be undertaken for blue or greenscreen applications.

For the past 5 years the ani HD lobby has been vociforous in their attacks on digial cameras using prisms and three chips.

A single chip system has always been the holy grail for the following reasons

ability to use existing film lenses

misguided

 rather than the subtle problems and operating

characteristics of what's inside those boxes.

http://www.ddisoftware.com/reviews/sd9-v-bayer/

 What are Dalsa, Kinetta and Arri D20 cameras?

These are new cameras that use single chip sensors. This enables use of existing film style lenses and optical viewfinders. The Dalsa camera has a 4046x2048k CCD sensor, the Arri D20 2880 x2160 CMOS sensor. The Kinetta may have a interchangeable sensor.