I have a shot I really like and I want to try and squeeze an exhibition quality A3 print
out of it if possible. (By 'exhibition quality' what I mean is, in this particular case, it must
not have any areas which look clearly out of focus - they don't have to be the crispest
or sharpest but they do need to look acceptable).
The problem:- it was shot in very windy conditions with a Canon 24-105mm at 24mm.
The exposure was 200th at f11. Overall it's fine - it's not the best onscreen, but I reckon
it will make a decent print. Except at the edges.... in my experience this canon zoom
does work well at 35mm and longer, but at 24mm the edges tend to become slightly blurred.
I'm guessing really but I'm thinking that the windy conditions have exacerbated this a bit.
Anyway, I wondered if anybody has any suggestions for a PS trick or similar that might help the
blurred edges print a bit better.
You can't create resolution where none exists to begin with. You can sometimes create the illusion of greater sharpness with increased contrast or acutance (edge contrast).
As for the Canon 24-105 lens, you should be able to get reasonably sharp corners at the wide end at f:11 if the lens is in proper adjustment and you use it properly. Perhaps your lens is out of alignment. That said, this lens, and the original Canon 24-70 are known to have strong field curvature at the wide end, which can make getting sharp corners more difficult. You can overcome or minimize the effect in part by how you chose the point of focus.