As Yashica was designing their first 35mm single-lens reflex camera during the Summer of 1959 (with help more than likely from the newly acquired Nicca Company) they faced another challenge… since it was decided to use an exclusive lens mounting system (Pentamatic bayonet mount) and not go with the more common M42 screw-in mount, they put Tomioka Optical Company in a bit of a spot.
Tomioka was their exclusive lens supplier through the 1950s but Tomioka also supplied a wide variety of lenses to other manufacturers as well. That meant that Tomioka would have to start building a new lens series with an exclusive mount very quickly in order to have enough lenses available to meet the demands of a new camera hitting the marketplace by the Spring of 1960.
Here is but a small collection of Pentamatic lenses that were available in the early 1960 time period.

One of the earliest examples in our collection of the standard lens supplied with the Pentamatic ’35’ starting in 1959. We interpret the serial number to read: 1959, December and the 1,630th lens made by Tomioka.

This lens is the standard lens for the Pentamatic II which came out in August 1960 (Yashica was still building and selling the Pentamatic I at that time. It was a rather odd lens to use as the normal focal length… 5.8cm (58mm) but with a slightly faster f/ 1.7 aperture.

Front view of the standard lens for the Pentamatic II. It is a very beautiful lens and it does provide a bright clear view wide open. Here it’s mounted on the Pentamatic I.

One of the earliest medium telephoto lenses for the Pentamatic. We don’t know what the ‘K.C.’ stands for… our guess would be that it applies to the coating on the surface of the lens. The serial number decodes to 135mm and the 927th made in the production run. We feel that this lens was made in 1959.

Original lens shade (as Yashica calls them) from the early days of production. The lens is the standard f/ 1.8 5.5cm lens for the Pentamatic I and S. From about mid year 1960.

A highly desirable early Tomioka branded lens for the Pentamatic. Another issue from 1959… the serial number 35 = 35mm and 246 indicates the production sequence. This lens is super bright and sharp. An excellent wide-angle lens for general photography.

The latest lens of the original production run that we now have is No. 60521000. The lens (above) shows that it is number 15,001 in the run which would put the lens into early 1961 production.
We hope to expand on more details of the early Pentamatic lenses in the near future. Stay tuned and thanks for reading our little blog!
Chris & Carol