quick summary on all 135 lenses that work very well* via adapter on a GFX 50/100 acc. my tests
multiply the full frame focal length by 0.79 to get the equivalent focal length for the GFX
Fringer EF-GFX Pro 500 NEW
Sigma 40f1.4 Art 750 USED
Sigma 85f1.4 Art 619 USED
Sigma 135f1.8 Art 1000 USED
Canon EF 100f2.8 L Macro 474 USED
Canon EF 200f2.8 L 350 USED