Nerd heaven! After years of speculation and almost constant searching, we’ve been able to confirm that Tomioka Optical began making lenses for Yashica’s new Pentamatic 35mm SLR camera in the latter part of 1959. The two lenses pictured below confirm (via serial numbers) of an October 1959 start of production. Yashica had filed for a trademark of the name ‘Pentamatic’ in September 1959 (in Japan). Since their new camera used an exclusive mount for its lenses, Yashica designers had to have shared their design with Tomioka as early as the summer (August ?) of 1959.

Using the rule of twos, these lenses are the earliest in our collection.

By serial number the left lens was built in October 1959 and it was the 92nd lens made. The right lens was built in December 1959 and by then Tomioka had built 1,630 lenses for Yashica.

No.  59 = 1959   10 = October  0092 = 92nd made

No.  59 = 1959  12 = December  1630 = 1,630th made  

Here’s our lens matched up to an advertisement in ‘Popular Photography’ magazine from the June 1960 issue. The lens in the ad is No. 59100581 which decodes to – October 1959, lens number 581 in the sequential production run. So in October, Tomioka had made nearly 600 lenses and by December they were up to 1,630 made. Certainly possible that they were averaging nearly 600 lenses per month in late 1959.

It’s a good find for us as the early serial numbers were just a guess on our part as to how they decoded. Having two lenses made before 1960 helped firm up our speculation. Lenses made in 1960 drop the month code in favor of a model number or code. A typical 1960 lens would have a serial number of:  No. 605xxxxx which would be 60 = 1960  5 = model code  xxxxx = production sequence number.

Serial number No. 60515001 decodes to 60 = 1960  5 = model code  15001 = 15,001 made since production began in October 1959.

If you’re a collector of Pentamatics or are just interested in Yashica cameras in general, this is important info. We know, total nerd stuff!

Thanks for your visit.

Chris