Thank-you, Hakkalo. This f1.2/12mm Elgeet that I wasn't so sure about has just won a reprieve this morning: when it arrived a couple of weeks ago, it would not focus to infinity at all, only macro. So, I took it apart and found I could make it "focus" to infinity by unscrewing the back rear element about 1.75 turns away from fully tight. So it kind of worked after that, in a somewhat arty Lens-Babyish kind of way (for example, my picture above). By no means sharp, and I knew my "fix" wasn't really the right approach at all.
Today, I realised I could take the screws off the focus ring - meaning that the ring turns continuously with no stops at either end of the focus range. I re-tightened that rear element I'd previously loosened... and voilá, now I can achieve good focus and it's become a much sharper lens (in the centre). Apart from infinity, I can also get close focus of just a couple of centimetres - probably a greater range than the lens was originally designed for!
Probably, someone had modified position of the focus ring so they could specialise in macros previously, and it just got sold to me like that. Here are a couple taken after my tinkering.