Yup, 3's and 5's work well in composition. I like the way you have arranged this shot. It suits mono (and the mono conversion is good). I would agree with Fay that a bit extra space at the bottom, just to bring the bolt heads fully into the frame. I kinda like the backdrop, I can just make out that it's a walkway/bridge(?) yet is well out of focus and makes the posts really stand out.
It's a good shot Fiona. Subjects like this are well worth exploring, do I see a 'geometric' phase coming on?
