Thanks Maris. All valid points regarding the focus. Using this particular lens os quite painful on the 8x10 tachi, a Camera you would be very familiar with. The front standard can barely hold the weight of this enormous lens on it's own, I've got a Manfrotto lens support that sits underneath the lens to add a bit of extra support. This makes movements with the lens incredibly awkward and cumbersome. Either ridiculously strong metal field/studio cameras or traditional tailboard design cameras would be able to make movement more fluid and less strenuous on the camera itself.
I did make up some waterhouse stops for this lens out of cardboard for f/8, f/16, f/22 and f/32 which would have certainly helped in bringing more of the face into focus but this was already a 5 second exposure @ f/4 with development pushed to 30 seconds (double the recommended time for a positive). Any longer exposure and the sitter becomes incredibly uncomfortable under the massive bank of flourescent lights very close to their face (just out of view of the lens).
I've given up on the studio, had several sessions through there and found it's just not for me. Much prefer environmental portraiture with natural light. Much easier and I like being outdoors with this process, coming from someone who usually shoots landscapes