Upload & Sell: Off
For use on the Fujifilm cameras, you want to try before you buy or find someone whose work with the lens you can check out. I'd be concerned about smeared edge detail and worse corners with the ZM18 on any of the Fujifilm X cams.
On NEX-5N and 6, it does pretty well.
On Ricoh GXR/M, it does fantastic.
I've never used it on a full frame digital camera and rarely used it with film as I did not own a finder for it.
Made with the ZM18 on the GXR, this slightly cropped snapshot had/has good detail right to the edges.
I've recently sold mine because I'm not expecting to ever see from anyone other than Leica a full frame mirrorless camera that works well with M wides and ultrawides except by accident, and, if such an accident should occur down the road, I can always rebuy it.
For a M-240 it'll probably be a great performer.