I have a problem with my Neway reference monitor on the SDI input and the Manufacturers in China are asking whether the output from the PMW-400 is RGB or YCBCR from the HD-SDI?
Would anyone know what colorspace the Sony PMW-400 (or similar models) output via HD-SDI?

Thanks

All HD-SDI up to 1080i should be Component 10bit 4:2:2, which is YCBCR. Remember, RGB is equivalent to 4:4:4.

Great, thanks!

RGB is not always 4:4:4 RGB can be 4:2:2 and YCbCr can be 4:4:4. RGB is most commonly 4:4:4, but just because something claims to be RGB it is most definitely not a a guarantee that it is 4:4:4.

But as Jack said the HDSDI out is indeed YCbCr.