i'm sorry bob i'm just an average guy with a camera...any possibility you could translate that into english?
Sorry, it was a bit late when I composed the reply. Reflecting telescopes use a mirror instead of a lens to focus the light so the surface has to be ground to a precise shape. If you double the size of the mirror then, for the amateur grinder at least, the difficulty of getting the precise figure isn't four times harder (the area is four times bigger) but eight times harder. I was just trying to make the point that similar logic applies to lens grinding though maybe not to such a degree with automatic machinery. The fact that faster lenses sell slower
doesn't help their prices either.