thanks for taking time to explain in detail. Really interesting.
Hi, Apart from the number of lens elements there are other factors that determine the image quality and formost is construction of the
lens mechanisms such as the barrel and helicoid ring from which the individual lens elements working as a group is shifted for focusing and
zooming,in other words mechanical precision.The accurate dimensions and tolerances which these individual mechanical pieces which are
assembled together to form a lens so to speak.So it's not only optical but mechanical precision that come to bear on this topic.
As you can imagine for a fixed focal length lens the variable is the focusing part and the rest is fixed physically.Compared to a zoom,focusing
and zooming are variable so you have more tendencies for dimensional error such as backlash or play in dimensional tolerances.I'm sure you
remember in physics laboratory class in school where you are asked to physically determine or plot the position of the image of a simple bi-convex
lens.so there is an element of spatial accuracy involved. Then you have the lens part where using different types of glass gives diferent optical
properties.Terms like crown and flint glass are commonly encounted.Very interesting indeed.