Apparently impossible ...

... Is to get a ring flash with "functioning" 77er adapter ring!
After I was already disappointed by another copy of another manufacturer, it is not much better, unfortunately at this brand product. The aforementioned adapter ring does not have the right size (too small) and "falls" thus directly into the filter thread and can not thus tighten.
Thus, the whole affair is not usable. Too bad, but to me it was enough with the first Bestellerei and Zurückschickerei ...