Thanks Satsuki !
Based on everything I've ever heard ("no S35 possible on the Arri IIC"), I never thought it would be possible to have it on this camera. But I draw the frame of the gate on the film and it fits the Full Aperture. I got it like that with a new PL mount. Maybe it was centered ?
As for the viewfinder, in order to have an idea where to frame, would the extra space be on the left side of the ground glass frame or right side ? Also, I launched a 2K scan at telecine of the Full Aperture S35 frame in order to be able to crop in post. Should I crop for a 1.85 academy ?
Thanks !