Mamiya-Sekor 645 Lens Variations

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:

Mamiya 645 C-S-N Lens Transition

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.

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