Soligor preset
See the auto-diaphragm lenses offered by Allied Impex. In contrast, a "pre-set" lens has no linkage with the camera body to stop down to shooting aperture. Instead, one click-stopped ring selects the desired setting and one free-turning one actually operates the iris. This allows a quick twist to go from brightest viewing aperture to a stop at the pre-set shooting value.
The advantage of omitting an aperture linkage is that extremely simple and inexpensive T-mount adapters can allow one lens to be fitted to a wide range of camera bodies (see the italicized list above).
Soligor preset
See the auto-diaphragm lenses offered by Allied Impex. In contrast, a "pre-set" lens has no linkage with the camera body to stop down to shooting aperture. Instead, one click-stopped ring selects the desired setting and one free-turning one actually operates the iris. This allows a quick twist to go from brightest viewing aperture to a stop at the pre-set shooting value.
The advantage of omitting an aperture linkage is that extremely simple and inexpensive T-mount adapters can allow one lens to be fitted to a wide range of camera bodies (see the italicized list above).