70 years of production. First launched in 1920 as Deltrintem. This one was made in 1990, at the end of its original lifetime. Well-performing optically (not excellent). Despite the latest T3M coating I prefer Deltrintem colours and its built. Jenoptem has light green-yellow tint. Diopter adjustment is too light and focuses somehow differently than Deltrintem. Maybe, I say maybe, Jenoptem is slightly sharper than Deltrintem. However, it is brighter than Deltrintem.
Further reading: Brin Best, Allbinos, Holger Merlitz