Dont think so both of mine have the same signature.
Originally Posted by goamules
They use the glass catalogue from the 50's the type IV summicron the glass catalogue from the 70's. The later lens will have better microcontrast on a MTF machine, if you tried, e.g. it is better then the type III summicron on a MTF machine.
The /1.8 will out perform the /1.2 and /1.5 detectable with slow film and solid tripod. but the /1.4 will be pretty good and very close to the /1.8 especially when both are at f/2... otherwise the difference is size and weight.