I don't remember ever owning an Isco-Gottingen lens. This is the first lens I have had that bears the Isco-Gottingen name. I don't know much about Isco-Gottingen except that they made some nice director viewing lenses, and the company is still in business. Some say that the name ISCO is an abbreviation of "This is Schneider's Company". How credible that is, I don't know.
This 100mm f4 is a triplet design with pre-set circular apertures. I just got it yesterday and took a few pictures with it today. Can't say anything about its optical quality yet, but it's a nice compact lens. With compactness, the aperture is rather small at f4.