So as you can tell from the heading this is beginning to get very technical in terms of setting up the C100's
Although this page has several "how to tutorials" that could be useful to us all.
C100 User Tip - Keep to the native (850) ISO
Found this whilst skimming through internet searches.
According to this dude at Cinema5D, He suggests that you stick to the native (850) ISO and if you drop it lower or higher you are do so at risk of losing quality!
Yet to try it out myself!
Feel free to have a read and let me know what you find! CF