Voigtlander APO LANTHAR 90mm f/3.5 MC LTM silver

APO refers to a type of lens construction that reduces color fringing, generally APO lenses are more expensie than other lenses in same type. Lanthar as far as I know refers to Lanthanum material which being used to build this lens.

I'm impressed by it capability to control contrast between bright sun area and shadow area in this picture

back light? No problem :D

now let's see how it detail for portrait

cropped 100% from above