The Starkish Xpander Lens enables lenses like the Angenieux Optimo zooms or older Cooke zooms to cover the full Arri Alexa Open Gate or Red Epic Dragon 6K sensor without any vignetting, so that users can make the most of their large sensor coverage.
The two versions are compatible with a wide range of zoom lenses, such as: Angenieux’s Optimo 17-80mm and 24-290mm, Compact Optimo zooms, 17-102mm, and 25-250mm HR; and Cooke 18-100mm. It will soon also be compatible with Fujinon and Canon zooms.
There is, of course, an image expansion factor of either 15%, giving a focal length that is x1.15 larger than indicated, or 21% (depending on version), with a subsequent loss of light of either 1/3 to 1/2 stop or 1/2 to 2/3 stop respectively.
Compared to a range extender, the Xpander expands the original image to cover a larger sensor area while maintaining the optical performance over the larger image area, while an extender only needs to maintain the optical performance over the original image area, which means it won’t get the most out of the sensor.
The Xpander Lens can be attached to most existing lenses where there is enough space between the back of the lens and the first filter. The current lens mount needs to be removed and replaced by the Xpander. It is not compatible with spinning mirror-shutter cameras.