Interchangeable mount lenses
Back in the 1960s when 35mm SLR cameras with interchangeable lenses were starting to become popular, independent lens manufacturers began offering alternatives to the camera makers' own optics. Some of these had fixed mounts for each different make of camera, but many had interchangeable mounts, so that the same lens could be used on multiple camera systems. In today's world of auto focus, electronically controlled lenses this idea has been abandoned, but it worked perfectly on the manual, mechanical cameras of the day.

Tamron introduced the T-mount system, which was widely adopted by Soligor, Vivitar and many other lens manufacturers and soon became something of an industry standard for manual lenses. The rear of a T-mount lens had a simple screw thread (similar to, but not the same as the M42 Pentax/Praktica screw thread), and each mount screwed onto that. Mounts were made for the popular cameras available at that time, including M42, Exakta/Topcon, Nikon, Canon, Minolta and many others.

The later T2 mounts were compatible with the same lenses, but were in two parts. An inner ring was held in place by three retaining screws, and if these were loosened the lens could be rotated to bring the scales to the top. As the lenses had manual diaphragms, there were no mechanical connections required to the camera.

Later, auto diaphragm interchangeable mount systems were introduced, including the Tamron Adapt-a-Matic and Adaptall, Soligor T4 and Vivitar TX, Sigma YS and others.

An Australian alternative, via Japan
Hanimex was a company set up to import and distribute photographic equipment into Australia, and eventually sold many products under its own name around the world. This included a range of manual lenses with interchangeable mounts, using a system similar to (but incompatible with) T-mount lenses and T2 mounts. They were functionally and operationally identical, but used a slightly larger screw thread (approximately 47mm in diameter) so lenses and mounts could not be swapped between the two systems. The mounts were usually supplied in a bright alloy finish while most T2 mounts were black, though this isn't a definitive method of identification, as some T2 mounts are silver coloured as well. The same lenses and mounts were also sold (and presumably made by) Tokina, as well as some other brands including Cunor, Vemar and a Yashica Yashinon-R 200mm. 

The range of lenses was initially fairly standard for the 1960s including 28mm and 35mm wide angle, 135mm, 180mm and 200mm telephoto. These were all made by Japanese OEMs (Original Equipment Manufacturers) to Hanimex's specification, and were of similar optical and mechanical quality to the equivalent Soligor and Vivitar T-mount lenses. Some were quite interesting in that they had unusual focal lengths (Hanorama 7mm f/5.6 circular fisheye, 300mm f/5.6 mirror), were faster than usual for the time (28mm f/3 and 180mm f/3.5), or had extra features (a rotating tripod mount on the 200mm). 

The Hanimex H mounts were made in fittings for popular SLR cameras of the time, plus some others including the Leica M39 thread (without rangefinder coupling, of course). These lenses can still be useful today, as with the appropriate mount (and/or extra adapters) they can be fitted onto many modern film and digital cameras. The Nikon mount, for example, will fit every camera made since 1959 with the company's standard F mount, and some others including Fujifilm DSLRs. The M42 mount can be used with extra adapters to fit Canon EOS, Pentax/Samsung, Konica Minolta/Sony AF and digital SLRs, and several of the mounts can accept extra adapters for Olympus and Panasonic Four Thirds and Micro Four Thirds digital cameras. Naturally there are restrictions, including manual focusing and diaphragm operation, but many cameras will still provide automatic exposure control in aperture priority auto mode (excludes some Nikon and Sony Alpha models).

Look out for Hanimex H / Tokina 47mm lens mounts being listed soon (March 2020).