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Summary

This is caused by light arriving at the sensor during the black calibration. Normally this is from a shutter that is failing. Change the shutter speed or ISO, then change it back.

In-Depth

A Phase One digital back relies on three external signals to do the following:

  1. Initiate the sensor's wake up sequence (the "wake up" signal)
  2. Begin the exposure (the "capture" signal)
  3. Communicate to the back that the exposure is finished and send the data.

In a normal sequence the shutter closes and then a signal is sent from the lens sync mechanism to the back telling the sensor to send data to the A/D converter. The problem in this case is that the third signal occurs prematurely; the shutter mechanism sends a signal saying the exposure is finished while the lens is still open. The blurring, streaking and color cast (pink or magenta, opposite green) occur because the sensor is sending data even as more light is striking it. This causes a black calibration that is invalid, which is then re-used until a new black calibration is created

To force the digital back to overwrite the invalid black reference, change the ISO one stop and capture an image. This will force a new black calibration for that ISO/shutter time. Then, change the ISO back to the original and capture once more. If the shutter is closing properly, it will result in a valid black calibration and the normal, expected image quality.

If you are using a Hassleblad CF lens or a lens equipped with a Copal shutter, this indicates that your shutter sync mechanism needs service. Occasionally, it will be a single shutter speed setting that is failing.

Working Around a Failing Shutter with a Phase One Wakeup Cable

It is possible to continue a shoot with a failing shutter, though it requires a few manual steps. The Phase One Wakeup Cable (Phase One part number 50300131) features a button that will create the signals required for capture. The button is highlighted in the image below:

Attach the Phase One Wakeup cable to the digital back via the minijack or via minijack to multiport adapter, then to the multiport. Do not connect the PC port end to the lens. To simulate the signals from the shutter:

  1. Wake up the digital back by tapping the button on the Wakeup Cable.
  2. Within four seconds, press and hold wake up button on the cable. This initiates the "capture" signal to the digital back. If there is longer than four seconds between the wakeup signal (step 1) and the capture signal (step 2), the back will report a Two Shot Timeout error. If this occurs, clear the error and start the sequence again.
  3. Fire the shutter manually. It needs to open and completely close.
  4. Release wake up cable to end the exposure.

Using this workaround, the "capture" time is effectively the amount of time that the button was depressed in step two, though the amount of light allowed to the sensor is controlled entirely by the mechanics of the shutter.

If the corruption continues, please contact the lens manufacturer for evaluation and repair.