Apple has recently launched a new OS – El Capitan (10.11.1). As expected, the initial release contained an enourmous amount of bugs and lacked support for PRO Photo & Video apps such as CaptureOne, which is why I always recommend to wait at least two months before updating on shoot computers.
Usually, I never jump into testing new OS, however this time something caught my eye – a rumour on a German tech site, which suggested that El Capitan finally supports 10bit displays. This was quite a shock, as Apple has continuously refused to provide professional users 10bit support despite countless requests. My guess for this swift change in direction is the new 5k iMac which offers a P3 wide gamut display.
So, what is the big deal about 10bit support over traditional 8bit? You have approx 1 billion colours displayed, compared to 16.7 million using 8bit, which gives a much higher accuracy in the change in tones, and a visibly smoother graduation (which you can test with a downloadable file here).
To have a true 10bit output you need to have all the components that support it, which are:
Image File (e.g 16bit RAW / TIFF) -> OS -> Software (e.g. Photoshop) -> Video Card -> Monitor LUTs -> Panel Depth
If any one of these are missing, you will only be getting an 8bit output.
I have done some testing on the new Mac Pro with Dual D500 Graphics cards, an Eizo CS230 Monitor, OSX 10.11.1 & Capture One 8.3.4 (which now officially supports El Capitan and appears stable), and I can confirm that we can now achieve a 10bit output!
Here is a more in-depth article on 10bit output: http://www.imagescience.com.au/kb/questions/152/10+Bit+Output+Support
As of yet (29th October 2015), I am sticking to 10.9.5 for shoot computers, with plans to upgrade to El Capitan as soon as 10.11.2 is released.