Thanks for your time Steven, some really useful advice there, yes I did use frequency separation first, the image wasn't as good as I'd like from the outset in terms of having to work on it. I'll be totally honest and add the fact that it wasn't even supposed to be a portrait shot, though it turned into one because when I was working on the whole image from which this was taken, I noticed just how great the facial expression is as a portrait. I decided that as I could have the crop with enough resolution to upscale it and then knock it into shape with some additional work and get something worth having at the end, I'd might as well persist on that path. See attached image below which shows the how the above crop evolved. It was shot on the move with a fair bit of wind blowing through the windowless carcass of the building, so I can't complain about having to tidy it a bit.
Sorry it took me while to get back, I've been shooting solidly since last Thursday and had a stack of images to get through.
Regards
Tim
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