While the pixel density on this camera is probably the maximum for S-35 where you can still see a difference between the best lenses and the second best, what's wrong with using older glass if it fits the look you're after?
See this article, which was already linked around here:
http://www.lensrentals.com/blog/2017/10 ... d-sensors/Oh, and the Sigma 18-35mm is pretty good glass, but It's so sad that the EF mount is not locking properly.
I hope someone will construct a better one for the UMP 12K.
You can always export a single frame under the Camera Raw tab in Resolve, but it'll be BRAW. Since you may want to grade it anyway, you can use the export possibilities in the Stills Gallery. But maybe one of the image processing softwares will get BRAW import? After all, the SDK is free.