Tirstin, Mongo is another vote for the 105 f2.5. Mongo’s is a “K” version (1974 -1977). Goes to f32 , has a rubber ring, multi coated blue/green glass, only 7 blades. Quickly converted the mount to AI. Fantastic piece of older glass and wonderful to use.
The f1.8 version is a fabulous lens without doubt if not “the” 105mm to have. However, it is bigger, heavier, harder to find, usually many many times more expensive (especially for one in condition worth owning). In the end, the difference may not be worth the much bigger effort - but there is a small difference.
the ability to quickly try both f1.8 and f2.5 versions before choosing would be ideal if circumstances permit. You will not be disappointed whichever you choose.
