I'd like to share with you a comparison I have just made between these lenses. The 'Made in Japan' is reputed to be the best of the standard f1.8 lenses. The 'Japan' is an f1.8 lens I've had for many years and have been very happy with. The f2 MACRO is said by many on the net to be the best 50mm lens ever made (e.g. look in www.photography review.com). I have not used this lens very much for 'general' use. It's always seemed a bit of a handful. Anyway, I have a certain arrangement I shoot (see below which is HALF the negative: the left hand disc is in the centre of the picture and the right hand disc is towards the edge).The lettering on the discs gives a good idea of sharpness. The LANTERN lettering is interesting because it is about 0.1mm high on the negative. The depth of field scale of a lens is defined by the maximum 'acceptable' size of an out-of-focus point source and is around 0.03mm (Olympus used 1/30mm according to an old OM1 instrution manual I have). So LANTERN is interesting: if the 'E' can be resolved, for example, the image could be regarded as 'acceptably sharp'.