What do the corners look like if you use the full frame and do not crop? Can you share an example?
I'll definitely be covering that in my YouTube review but seeing as how it's #3 in my backlog, that video is a couple months out.. Happy to give you the gist of it now..
There is significant vignette due to the hood and some color shift up to about 18mm, after that all is pretty manageable. Overall, some mustache distortion which is a bit difficult to correct for in C1, but nothing terrible. I have read about some people cutting the hood which apparently helps quite a bit, but this is from LensRentals and I have heard they frown upon that kind of thing..
I'd treat this as an 18-24 on GFX full sensor, unless, like me, you typically shoot 16x9 or x-pan, then you can get away with 16mm if you crop in a bit to lose the color shift on the edges.
You may notice some of these seem soft, not sure why, must have to do with the C1 export and sharpening settings, will look into that.. but here are a link to a couple raw files.. very nice center sharpness in the raws.
