Loving this thread as i'm considering getting a housing for my A7R IV; all set for the macro front, just figuring out WA options ;-)
Couple questions:
1) How well does the Zen 100m work with the fisheye setup ? (I think Simon has some experience - do you have pics to share?) Also did you need to use extra extension on top of the N100->N120 35.5mm adapter?
2) Would the same setup (N100->N120 adapter + Zen 100mm) work for 28mm f/2 + Fisheye Converter? I'm considering that as it's lighter than the canon + metabones combow.