Sunpak flash units of the DX series were made during the latter part of the film era, from the mid 1980s until at least 2005. Most have “DX” as part of their name and employ a plug-in module that provides the unit with its hot shoe foot. Cameras of that era were acquiring features such as indications of the flash status in the viewfinder, which required communication between the camera and the flash unit. Because there was no standardisation of these auxiliary signals, for the DX series Sunpak offered a different module for each camera brand (or even model) to provide the same features as the camera makers' own flash units.

The DX units were of high quality, and the more powerful ones were aimed at the professional market in which they were the main rivals to Metz and Vivitar as independent makers at that time. These often exceeded the camera makers’ own branded units in both quality and features, while at the same time usually costing less. It is believed that some camera branded units were in fact made by Sunpak under contract.

All the DX units I have tested are safe to use on modern cameras with the correct module as long as the camera hot-shoe contact layout has not changed since their time.

The Guide Numbers quoted in this article are in metres at ISO 100, with the unit set at the beam angle for a standard lens : ie a 50mm lens in the case of 35mm or Full Frame format. That was the older convention. The marketing of modern flash units usually quotes a Guide Number with the unit set at it maximum zoom, which sounds better but cannot be directly compared with the older convention.

SOME CONTEXT [scroll straight down to the DX units if you want]

The DX series belonged to the transitional period in flash unit design in that most of them have all three of the then basic modes of exposure control – Manual, Auto, and TTL.

The earliest electronic flash units had only Manual control, in which the photographer set the camera lens aperture to a value according to the Flash Formula. The Flash Formula relates aperture, film speed and subject distance; you can work it out yourself (it is not hard) but you were usually helped by some sort of slide rule or an engraved table on the unit. From about the mid 1970s Auto mode was added, in which the exposure was controlled by a photocell on the flash unit which quenched the flash when enough exposure had been reached. Neither Manual nor Auto modes require direct communication between flash unit and camera. However, camera makers were introducing subsiduary features such as “Flash Ready” indications in the viewfinder, which did require communication.

Then from about 1980 the more advanced cameras introduced TTL (Through The Lens) control of flash, which used a photocell somewhere behind the camera lens to control the flash unit. As implemented in the film era, this was the best method of controlling flash exposure, ever. But at the time there were still plenty of cameras around without TTL capability, so all the DX units except the DX R12 were provided with all three methods of control.

From about 1990 however, flash unit makers began to omit the Auto modes (the Sunpak DX-R12 being an example) in the expectation that all new cameras would be TTL capable. This has unfortunate consequences today, because the technology of TTL control with film cannot be used with digital cameras, and current (c2020) digital cameras use a different, incompatible, and somewhat inferior TTL method. But the Sunpak DX units are still satisfactory on modern digital cameras in their Manual and Auto modes, and in some ways the old Auto mode is superior to the TTL of the digital type.

Sunpak also made some non-dedicated flash units at the same time as the DX series. For example the Sunpak 383 was the non-dedicated equivalent of the 36DX and cost less. The flash trigger was the only connection with the camera in these units.