Anamorphic lenses contain optical elements that capture a 2.39:1 image and squeeze it onto the 1.78:1 ALEXA imager. With the Anamorphic de-squeeze activated, the image appears "normal" in the camera for monitoring and playback.
The Anamorphic De-squeeze includes four modes for monitoring: De-squeeze off, De-squeeze 2.0x, De-squeeze 2.0x & magnify, and De-squeeze 1.3x.
De-squeeze 2x
2x Anamorphic lenses squeeze the image by a factor of two. In 2x, the de-squeezed full sensor image appears normal in the viewfinder and monitor with extra recording image area to the left and right of the 2.39 aspect ratio.
De-squeeze 2x & Magnify
In 2x & magnify mode, the 2x image is enlarged to practically fit the 2.39 aspect ratio, with little extra area on the left and right. This mode is for monitoring use only, as it does not work in Playback mode.
De-squeeze 1.3x
Developed specifically for the 16x9 sensor, the 1.3x anamorphic lenses squeeze the image by a factor of 1.3 instead of 2. Used with 1.3 lenses, the De-squeeze 1.3x mode will compensate for the squeeze and fit the 1.78:1 (16x9) sensor size.
For more information, download ARRI's white paper on the Anamorphic De-squeeze option.
