Technology    

The Digital Adapter is attached to the outside of your housing in a way that allows the internal flash to illuminate it. Whenever the Digital Adapter detects the abrupt rise in brightness caused by a flash, it fires off the external flash. The quantity of flash light depends on the duration of the flash; most digital cameras offer a flash firing time of some 10µs up to 500µs. How the burning time is being calculated differs from manufacturer to manufacturer.
The three most common techniques:
  • Manual strobe release: Some cameras fire the internal flash always at full power and adjust the sensitivity of the CCD sensor accordingly. This leads to the external flash burning equally long. Although the Digital Adapter won't adjust the released power, an external, manually adjustable strobe can still produce good results. As this technique consumes quite a lot of energy, it is no longer used in modern digital cameras.

  • Sensor strobe: Another frequently used method in digital cameras is a photosensor. It measures the brightness during the flash, then causes the camera to quench the internal strobe once enough light has been emitted. The Digital Adapter recognizes this process and quenches the external strobe within 4-6 µs.
    The camera chooses the necessary amount of light. Combined with manual options available at your camera (+- EV), it will lead to very satisfying results. In addition, this funtion allows you to suppress a pre-flash, e.g. Panasonic, Fuji or. Leica

  • Pre-flash (measure-flash): A short pre-flash illuminates the scene. The camera's subsequent calculation of the adequate burntime for the mainflash is based on the amount of reflected light. Some 100ms later, the main flash is fired for the photo exposure.
    The Digital Adapter adapts to this process and transfers the signal for a measure-flash to the external main flash. Consequently, the camera notices the additional light shed by the external flash and will take it into account when firing the main flash. Simply put: As the camera is unaware of the external flash, it is fooled into calculating a burntime for a scenery that doesn't need much exposure.

    This is the most common technique used for digital cameras. It allows the Digital Adapter to realize its full potential!

    Example: For Olympus cameras such as the C7070 or C8080, the time span between pre-flash and main flash is about 100ms (You'll find exact timing data for many cameras in our database). Within this interval, the external flash has to fire both a single pre-flash (duration: 60...80µs) and the main-flash (duration: 100...200µs). Since the pre-flash doesn't consume much power, strobes such as the Sea&Sea YS-60TTL or Ikelite DS-50 master this task easily. The same goes for the Digital Adapter: It recognizes two flashes even within a short span of less than 10µs!

    Another feature: Some cameras reduce the so-called "red-eye effect" with a pre-flash. The Digital Adapter allows you to fade out up to three pre-flashes. (e.g. Canon, HP or Olympus)

Working scheme of the Digital Adapter 2:

Pre-flash cameras use the pre-flash to determine the burning time for the main flash. The amount of light is measured by a sensor in the camera or - just as "classic" TTL - by the lens. Simply put: If much light is reflected after the pre-flash, the intensity of the main flash has to be reduced accordingly.


The following experiment demonstrates how the DA2 works:

The test is carried out with an Olympus 4040, the burntime of the strobes is recorded by an oscilloscope. A dark wall is photographed from a distance of about 3m. It is to be expected that the small internal strobe won't be up to the task. All pictures are shot in automatic "A"-mode without adjustments of exposure.

Pre-flash: The pre-flash of an Olympus lasts always for about 55us, no matter what the motive is. During that short span of time, the Olymympus calculates the necessary amount of light for the main flash that will follow about 100ms later.
No external strobe: The main flash burns in full brightness for about 900us. The slow downward slope of the light curve towards the end of the exposure shows that the flash consumed the maximum amount of power.

With external strobe and Digital Adapter: The recorded duration of the main flash shows a much shorter burntime of the internal flash. As the external strobe also burns during the pre-flash, the camera reduced the intensity of the main flash quite considerably. The sharper decrease of the light curve (note the smaller TIME/DIV-setting) shows that the flash did not yet burn at full brightness, but was regulated by the camera.

Only the absorbed energy needs to be replaced, meaning that the battery will last longer and the camera will sooner be ready for another picture. Particularly cold water divers - who otherwise might have to wait for up to ten seconds for the camera to recharge - will enjoy this aspect.

Additional switch-on and switch-off delays can be configured in 50µs steps. When used in combination with the camera's manual adjustments, almost any combination of digital camera and strobe is attainable. Even a weak external strobe will improve image quality substantially in clear tropical waters.

For high performance strobes such as the Sea&Sea 350, the Digital Adapter can use extremly short control times, so it is also useable in the macro range.

Even if the digital camera's builtin flash is obscured, for example, by a wide angle lens, usually there is enough light to trigger the Digital Adapter. However, if your housing is completely opaque you cannot use Digital Adapter!

Also film/analog photographers can profit from the Digital Adapter: fire a 2nd or 3rd strobe TTL-controled, wireless and reliable! Even from several meters distance!