This page has links to all information you should need about the Arri Alexa
The first camera on the scene, the Arri Alexa remains at the center of the family; it is the keystone of a modular and upgradeable system with exceptional image performance that is simple to operate, reliable in even the most extreme environments and versatile enough to cover a wide range of workflow and budget requirements. The original ALEXA comes with a 16:9 sensor and the original SxS Module that accepts two SxS PRO or SxS PRO+ cards for recording in-camera ProRes or DNxHD.