Having acquired a used Mamiya 645 Pro and wishing to add some primes to my collection, I was surprised to learn how many Mamiya-Sekor 645 lenses and model variations exist.
So I decided to do a little research to understand the differences between early C lenses and later N lenses, not forgetting the transitional S lenses.
There seems to be some myth surrounding optical design and build quality, with most buyers opting for the later N lenses. However, apart from optical coatings and cosmetic changes, many of the N models have exactly the same optical design as their predecessors.
The table below shows my findings for the more common Mamiya-Sekor 645 lenses:
Points of interests:
1. Date overlap of C to N lenses probably relates to a phased transition since Super, Pro and Pro TL manuals refer to an increasing number of N lenses in their system charts.
2. Only two S lenses seem to exist both having revised optical designs. The 45mm f/2.8 S has a smaller front element and modest changes to internal elements. The 55mm f/2.8 S is an optical re-design with one less element.
3. S lenses show little variation in build quality to C lenses – retaining aluminium barrels and silver focus ring trim.
4. N lenses are generally lighter than C or S lenses using thinner aluminium barrels and plastic aperture rings. N lenses also have revised optical coatings improving colour, contrast and reducing flare.
5. Many N lenses ceased production in 2006 (end of Pro TL line), however the introduction of the Pro TL Colour may have extended production of some N lenses until 2008.
6. Dates are derived from archived camera manuals, magazines and brochures.