Ian Stubbington - no it's the Mamiya design for Nikon that was branded under Ricoh after Nikon didn't keep the lens for the Nikkorex F. It fits the Ricoh Singlex that has a modified Nikon F mount. The later Ricoh TLS, TLS II and Sears branded SLII Ricoh used the M42. Nikon F mount lenses will fit the Ricoh Singlex, but unfortunately the Ricoh F mount lenses won't fit on Nikon without modificaton.
That's the M42 fit , not the Nikon version .
Ian Stubbington - no it's the Mamiya design for Nikon that was branded under Ricoh after Nikon didn't keep the lens for the Nikkorex F. It fits the Ricoh Singlex that has a modified Nikon F mount. The later Ricoh TLS, TLS II and Sears branded SLII Ricoh used the M42.
Nikon F mount lenses will fit the Ricoh Singlex, but unfortunately the Ricoh F mount lenses won't fit on Nikon without modificaton.