It is angled and not easily seen.
Maybe use a magnifying glass.
Between the tubes.
It may be that different markets have different markers, as well as different year numbers.
Maybe 3rd digit model indicator??
I spent ages going through Dallmeyer manufacturing lens ledgers.
Kodak, Hasselblad and others have codes.
Nikon camera numbers are not as they seem.
Minolta numbers strange.
Canon lenses have factory indicators.
Perhaps Bletchley Park could help.
Last edited by Binastro : Tuesday 20th September 2016 at 19:04.