2017 MacBook Pro 13" with Touchbar (USB-C) can't connect to LED Cinema Display 27" (Mini DisplayPort)
I have the exact same problem and after much search, came to this solution:


Dual-Link DIV to DisplayPort using Apple's connector
DisplayPort to USB-C using this connector Which is a  USB-C to Mini-DisplayPort and Charging Port Adapter {Amazon.com}


Keep in mind that the Cinema display also needs a USB-A connection (I'm guessing to provide power to some internal circuit for link negotiation?), so you'll need a separate adapter from USB-C to USB-A.

I'm also an amateur photographer and shoots with a Canon 5DsR, editing my photos using an AdobeRGB LG 4K display (10-bit color to support AdobeRGB). I've also tested the DisplayPort adapter on this display and it works flawlessly.

On a side note - reason why you'll need a separate adapter for USB-A instead of having the USB-A built-in to the DisplayPort adapter is that only way for USB-C to support DisplayPort data-rate is using Display Protocol, which turns a bi-directional USB connection (10Gbit/direction) to a uni-directional output port (20Gbit total). If you work out the math: 3840 * 2160 * 10-bit color per channel * 3 color channels (RGB) * 60 Hz = 15Gbit/s.