Summary
In many scenarios, a large format camera is used with a copal, external, or built-in shutter. These shutters can be a weak point in terms of the synchronization signal from lens to the camera back. In general, the shutter is the source of most issues when using large format. Using older lenses and not digital prepared lenses can cause image degradation.
Phase One backs require two signals provided by a camera/shutter. The first signal provides a wake up impulse for the digital back and the second signal is the integration signal. This is normally provided by the camera's flash connector.
In-Depth
The Phase One One-Shot sync cable
When using Phase One backs on a studio camera (4x5) with a mechanical leaf shutter lens, you have to fire the shutter twice within 2-4 sec. if not, the back reports an error message (something link...sync error etc.). The first signal “wakes up” the camera back. The second signal captures the image. Medium format camera bodies perform this automatically.
The One-shot release cable has a little contact built into the housing that connects to the digital back. By pressing the contact the back receives the “wake-up” signal and prepares the back for capture. It will remain active for four seconds.
This cable reduces the work of firing and cranking the shutter twice and reduces the risk of moving the camera due to the cranking of the lens shutter.
Phase One One-Shot sync cable
The Phase One P 20 and P 25 can be used on most large format cameras with the optional Phase One FlexAdaptor and the enclosed lens sync cable.
The P/P+ System supports most electronic shutters such as the Horseman ISS G3 & G2 and the Rollei Lens Control S and Schneider Control ES. Schneider Control ES will work in 2-shot mode. This means the release on the hand-held unit must be pressed twice to create an exposure. For flash use, connect the flash sync cable to the flash port on the Phase One Digital Back.
If "Release: Key" is displayed then the shutter can be released with the right hand LCD key ("Release").
If "Release Ext." is displayed, the shutter CANNOT only be released externally by the Digital back or computer.
We recommend using "Release: Key" only.