Good Evening, PDH,
I have a 52mm Miranda Macron lens which I still use when I need to do occasional 35mm copy work. I bought it back in the 1970's for my Miranda Fv; it functions perfectly now on my Miranda Sensorex. It is a pre-set lens, but that's no problem at all for the kind of work I do with it. I have no information on the number of elements or groups, but six elements in four groups sounds about right. I know that it produces excellent results. As you note, it can achieve 1:1 without any extension tubes. I don't use mine very often, but it's one lens I think I'll keep forever.
Konical