Nikkorex F and Ricoh Singlex

The twins adopted to two different families.

With proper meters attached.

The Nikkorex F is said to be Mamiya made. It's the first camera
to employ the Copal Square metal blade focal plane shutter unit.
When Nikon discontinued the Nikkorex F, Ricoh bought the production
line. It's about the time Ricoh was to embark on SLR market but their
own plant was not yet ready.

Some say about the similarity in Ricoh Singlex lens to the Nikkor
lens and the possibility of Nikon lens in Rikenon name.
I have closely examined the Rikenon lens and I am sure there is NO
similarity in Ricoh and Nikkor lenses. The construction and workmanship
in the Rikenon lens is not at all Nikkor. It might have possibly been
made by Mamiya or else by Tomioka.
The lens mount of the Ricoh Singlex is slightly different from
the Nikon F mount. All Nikkor lens can fit on Singlex body. But
Singlex lenses are difficult to fit on Nikon cameras.
IMHO, there must have been some agreement among three companies
on making a Ricoh camera of Nikkorex design.

Here are interesting lenses which may be missing links.
"Nikkorex lens Sekor" 135/2.8 and 35/2.8.

I don't know whether Mamiya marketed these lenses themselves or
EPOI ordered them for a inexpensive substitute for Nikkor lenses.
Someone once told me that Mamiya sold the Nikkorex F under thier
own name. But I'm not sure at that.

Ricoh Singlex was supplied to Sears Roebuck and co. as Sears SLII.
It was just a "sticker tuned" version of Ricoh Singlex.
I won't dare to remove these stickers, but I bet there will be
Ricoh names engraved under these stickers.