MXP wrote:


They didn't use some of the rare and expensive glas sorts to be able to use
less elements?
They didn't have the computer power we have today so maybe they could
compensate by using more expensive glass which are not used today?


They designed differently. Some of the complicated designs with many
elements would have been busts without all sorts of coatings. OTOH if you
don't have those coatings you use different designs.

Nick