This question has been posted many times, but it is impossible to do something working with the new versions of Blender.
I am trying to obtain the real depth map of a scene, meaning that I need to have as output a file containing for each pixel the real distance from the camera. I tried to put the output file format to OpenEXR, but everytime I cannot obtain the depth values. I have tried to use the 'Compositing' pannel, or in a simplier way to use the 'Output properties' pannel. Everytime, I only have a RGBA datafile, even if the 'Z-buffer' option is marked. It seems that this option does not work properly...
EDIT : Thanks to @lemon and this question, I was able to obtain it! But the values are clipped to 6.5504e4... I also obtain a file with 3 channels, the three of them being exactly equal. How can I obtain a file where the values are not clipped?