I have an old Ricoh 35 mm SLR camera. It uses a Screw mount lens system as oppose to other 35mm cameras that adopted the Bayonet mount system otherwise know as T-mount. I am looking for a conversion ring that will allow my camera to accept T-mount lenses since there are not many Screw mount lenses out their anymore. I have looked on line and have found only converters that will allow me to use cameras with T-mounts to use screw mount lenses but nothing that will fit my needs. Am I wasting my time or are there converters out there that will meet my needs?
M42 vs T-mount vs K-mount
T-mount has 42mm x 0.75mm pitched threads. Your Ricoh probably uses the M42 mount, which has threads with a pitch of 1.0mm.
Ricoh switched to using the Pentax K-mount in 1977.
The following cameras use the M42 mount:
The following cameras use K-mount:
For issues concerning the use of lens adapters, see Can I use lens brand X on interchangeable lens camera brand Y? In particular, Registration Distance / Flange Focal Distance will be a problem.
The M42 screw mount has a registration distance of 45.46mm. Most commonly-used modern mounts have a shorter registration distance. A notable exception is the Nikon F mount, which has a registration distance of 46.50mm.
Many old M42 lenses are available with various levels of quality or interesting characteristics. What do you hope to gain by seeking to use a new lens with an old body?