1dx mk2 4k outputting 1080p?

[brianftpc]

I understand that the 1dx mk2 does not output uncompressed 4k over HDMI. I was videoing a graduation today when I realized that I needed more focal length. I was using a 70-200 with the 2x III extender. I remembered that the 4k had a 1.4x crop. I couldnt use it internally bc the graduation would be around 2 hours. I connected it to my Atomos Ninja blade however it doesnt do 4k. so I set the camera to 4k 29.97 and the atomos to record in 1080P 29.97. Surprising to me the atomos received the signal. I watched the video afterwards and it looks no different quality wise than the uncompressed 1080P coming from the HDMI. So my question is....what is coming through that HDMI to the Atomos when the camera is set to 4k. If it is 1080P what am I losing compared to the 1dx mk2's normal uncompressed 1080P stream.

 

[Sharlin]

I'm pretty sure the camera negotiates the resolution and frame rate with the other endpoint, overriding any user settings. I think that was even mentioned in the manual.

 

[brianftpc]

thats what I thought as well however it still gave me the 4k crop.

 

[gsealy]

I am thinking that you get the same frame as you would get with 4K, BUT it is at 1080P. Not sure how they do that, some sampling methodology.