Thanks David. I have a MG sight that was made in 1912 so it just goes to show how advanced the Germans were in machine guns and optics. I also picked up through a larger deal a pair of beautiful ZF sights that are pre WWI for rifles. I am told they did see some military service at the beginning of WWI, both attached to German and British rifles but I do not know much about them. If there is a rifle optic expert out there I would be keen to know value and rarity - i will post some images.
Also replied David via MP.