English: Sunpak auto 30 DX electronic flash unit, released in 1981 for contemporary electronic 35 mm film SLR cameras such as the Canon AE-1 or Leica R4. It is equipped with a flexible head (330° of rotation, 90° of elevation) and designed to take quick-swap interface modules. The CA-1D paired with this example comes with a standard hot shoe and additional Canon-specific contacts. Modules for Olympus (OT-1D), Minolta (MX-1D) and Nikon (NE-1D) were available from the factory, and later units shipped with the product-improved auto 36 DX flash also appear to be compatible. It can function as as a separate auto slave or be triggered remotely, though optional accessories are required for either use. Power is supplied by four AA batteries, an external 510 V battery pack or AC adapter. Furthermore, a timer-based auto off feature was implemented to extend battery life in AA operation.

The Sunpak is designed to work in conjunction with the camera's aperture priority program. Firstly, one is to set film speed and select distance to the subject: long (A green, 2 to 15 m), intermediate (A yellow, 1 to 7.5 m) or close (A red, 0.5-3.7 m). Secondly, the lens should be adjusted to the suggested aperture, for example f4 for ASA/ISO 100 at 7.5 meters. The built-in photodiode should then measure the light reflected by the subject and automatically regulate the flash duration for correct exposure. Manual mode provides direct control of light output (full to 1/16) in relation to flash-to-subject distance and aperture for correct or deliberate under-/overexposure, useful for e.g macro photography or fill flash. For example, the unit indicates f5.6 for ASA/ISO 100 @ 1/8 power at 2 meters.

Trigger voltage with fully charged Ni-MH batteries was measured at 6.5 V, which means it should be safe for modern DSLR cameras such as this Nikon D7000. Provided the Auto ISO feature of the camera is disabled, automatic flash mode also works as expected.