The main problem was light/colour - so, opportunity, not optics. This was completed late last fall, and whenever I came across it since, I had either packed the wrong lens or, more often than not, light wasn't favourable. Actually, I've shot wider lenses in the past to capture more of the whole stretch of murals already, but I had wanted to "isolate" this "panel" for a while, and I think I succeed this time in nice enough light. A 24mm-e lens would have made it it easier, though - with the 27mm-e, I had to step out on the road for a moment (not a lot of traffic, usually, so, not a big issue).
But I acknowledge I could have chosen better words to describe what I was going on about ...
M.