My opinion:
If you're working with 4x5 it's going to be much slower to focus, and so you need to get those poses locked in as "candid" can be really tricky - which is really what I'd be expecting from someone trying to illustrate someone's character with a portrait. Unless you're shooting up at f/11 where you have a degree of flexibility with depth of field.
4x5 portraits that I've seen come across as quite formal because of this, so it's really worth having a good think about the poses you want, to express the vision you've got.
Your subject looks pretty grumpy. Not sure if that's the intent, and by only seeing this one slice it's probably a bit presumptuous, but I'm curious as to how you're going to explore their similarities and differences. The fist-under-chin doesn't work so well for me and adds to the grumpy confrontational feel. Both images are quite different. The grey hoodie is more prominent in the head & shoulders shot and the turn of the head is a bit too extreme with the [camera] left eye fighting for dominance and losing. The second headshot image is much better with the direct eye-to-camera, fist under the chin, central composition that sends a more powerful "strong" image rather than grumpiness. The forward head angle implies the need to be resting the chin on a table that we can't see as opposed to floating in the air like in the 1st image. I still feel that it's too prominent though and if you need it, I'd raise the light a bit or do some PP to reduce the dominance of the hand. It also squashes the face, as most people tend to relax their head onto it, which can be an unforgiving look. I also think the vignetting is a bit too hard, but it's a minor point as it's not massively noticeable.
I think it's a great idea, and would make an excellent tryptich if you can get the poses and expressions right on all three characters. 4x5 is quite brave for a project like this!
Hope that didn't come across as too disheartening Pete. I'm just one person with one opinion! Feel free to ignore it.
/opinion
Hey no problem!
These were literally 5 minutes. I've never used the ring light before
Kirstyn WAS extremely grumpy, the kids had been ar5ing about at bedtime, when she came down, I had set this up and sprung it on her. She rather tersely agreed to sit for a few minutes.
Kirstyn is the most agreeable between her and sisters
The final thing won't be grumpy, this was more about 'does this light work as well some people claim?' (I'm not convinced), 'does this backdrop work?' (I'll use the same bachdrop and lighting setup for each)
I too was thinking of raising the light, and camera. Also a longer lens. I've not long aquired this 1D Mkii and am slowly getting to grips with it.
In terms of pose, I'm thinking faily neutral. This isn't a corporate brochure headshot, it's not a passport, it's not a 'smilley, smiley very smiley' thing either. My thing I guess is to have them lit and posed similarly. My thing about b&w is that they are a trio consisting of blonde/green eyes, redhead/blue eyes, brunette (currently silver and pink)/hazel eyes. It's the most obvious single physical difference between them so I thought to strip that away. In terms of skin tone, they are all typically Scottish :- milk bottle white verging on see-through.
Interestingly, there exists an engagement shot of K and I embracing and I kissing, in b&w. One of the nephews (his mum is the redhead asked his mum why she was kissing uncle Pete?
I used a lot of 5x4 back in the day, recently aquired a Cambo and want to throw myself back into it. Might as well be hung for a sheep as a lamb!
I used to really enjoy studio work in 5x4, I was lucky, back then I had a great mentor at my workplace in my teens, and a bit later on at uni, a couple of great lecturers and facilities. The head of school was pretty well established and respected in portraiture, shot a lot of material to go with interviews/books on artists, poets authors, musicians etc. He was a great believer in KISS/less is more.
In all likelihood I'll shoot it with everything I've got from DSLR, 35mm, MF and LF, see what works.