I put Zeiss UltraPrime 50/T1.9 cinematography lens on my Sony A7r.
I compared its central wide open SHARPNESS/CONTRAST performance (f1.7 equiv) to that of wide open Sony Zeiss Sonnar 50/1.8 FE and Konica Hexanon 60mm/f1.2 (closed to f 1.7).
The UltraPrime on A7r vignettes in the corners, but that was not relevant here. S35 cine lenses have similar image circle to that of APS-C. Ultraprimes from 85mm up have the wide open image circle sufficient to cover a full photo frame (36x24mm). The 50mm full shot is attached , anything wider would have the vignetting bigger and bigger.
I took a lot of test photos outdoors all lenses at f1.7 (f1.8 with the Sonnar) with focus distances from 5 to 40 meters.
And one indoors setup from ca 1.8 m--the bottles.
Only the indoors close shot shows some slight differences in the performance of the three lenses. I am attaching the three 100% crops so you can see for yourself.
Outdoors, whether it was the long focussing distances or the atmospheric conditions (air clarity, changing light) the differences were ever so slight Shutter was 6000/8000, ISO200. The Ultrprime and the Hexanon might have a slight edge in contrast there, but nothing really that could not be equalized in post. All raws developed in LR5.3 at standard setups.
The Sony Sonnar 55mm is an amazing lens for the price. The Hexanon long has been my favorite for the focal length, but for practical reasons it will remain on my Leica M8. The Ultraprime (costing 15 times the Sonnar) is great for cinematography and has many features needed for the job (lack of breathing, callibrated distance scale etc etc) but picturewise is only slightly ahead of the Sony. If at all. In more controlled conditions they might perform at par.
The 100% crops were originally ca 1800px wide, here they became much smaller and the differences became almost invisible. Sorry.