Thanks Gareth - and also to those kind people who "liked" the shot. It's very early days for me with this back (I've only been out and shot with it twice so far as I'm very time poor at the moment), and I have a LOT to learn - especially about getting the most out of the image on the post side of things - so the likes and kind comments are extremely encouraging
I have a bit of a problem in that I don't have a decent monitor (recommendations welcomed - I want to get one soon), so what I'm seeing is almost certainly not what you're seeing, nor what it should actually look like.
Shot with the 80/1.9.
Here's one with the 50:
I deliberately haven't touched any development settings (other than WB) on this one and would be very welcoming of any suggestions as to how to improve it.
/edit
(Should point out that of course I can work with the file and improve it myself, I thought it would be best to start with an untouched image when reaching out for help and guidance. One thing that is astonishing me is the sheer latitude of adjustments possible with files from the IQ180 before things start to break up. It really is mind-numbing what this back can do.)