The idea is that it will adjust the camera's front and rear blur automatically depending on your camera settings and according to a real physical depth of of field formula… Cinema will use this camera information when outputting your depth map channel – just activate the Depth channel in your Multi-Pass render to use in compositing.
The reason I made the DoFcam was because I wanted to output depth maps from Cinema which at least had some kind of real physical foundation. I also wanted the camera's depth/blur settings to change automatically during animation when linked to a target object.
The camera itself is very simple, I've just added some user data under the heading DoFcam which includes a Target Object link (which you don't need to use if you don't want to), an f-stop parameter and 2 optional adjustment parameters. I've also made a quick video (link below) explaining the above.
I've done my best to test everything works OK, but if you come across anything wrong with it, please let me know. One problem I did encounter was with the Document Scale parameter in C4D12's Project Settings. Although it doesn't appear to break the camera, I think it's best to keep this set to millimetres so that the measurements make sense…
DoFcam for C4D 11.5 (http://www.benek.co.uk/tutorials/DoFcam_C4D115.c4d.zip)
DoFcam for C4D 12 (http://www.benek.co.uk/tutorials/DoFcam_C4D12.c4d.zip)
DoFcam Demonstration video (http://www.benek.co.uk/tutorials/DoFcam.mov)
Depth map tester vid (http://www.benek.co.uk/tutorials/DoFcam_NEW_C4D_enDoFinBlurH264.mov)