Friday, February 03, 2017

ON Semi Sensors Power ARRI Cameras

ON Semi says that for the past five years, every movie to win Oscar Award – Hugo (2011), Life of Pi (2012), Gravity (2013), Birdman (2014) and The Revenant (2015) – was captured using an ALEXA or ALEXA 65 digital camera system from ARRI. For 2016, four of the five nominees for Best Cinematography were again captured using ALEXA cameras. These cameras high DR, natural color reproduction, and high sensitivity, all begin with the performance of ON Semi image sensors used in the system.

ARRI publishes an explanation of image sensor technology used in its cameras:

"Although the science behind the breakthrough performance of ALEXA's custom designed CMOS sensor is complex, the use of large photosites and a Dual Gain Architecture are its two main principles.

By employing unusually large photosites (in today's world of tiny cell phone sensors), ALEXA's sensor exhibits high dynamic range, high sensitivity and low crosstalk. The larger a photosite is, the more light it can capture and the lower the noise.

The Dual Gain Architecture simultaneously provides two separate read-out paths from each pixel with different amplification. The first path contains the regular, highly amplified signal. The second path contains a signal with lower amplification, to capture the information that is clipped in the first path. Both paths feed into the camera's A/D converters, delivering a 14 bit image for each path. These images are then combined into a single 16 bit high dynamic range image.


  1. Assembly seems to me quite tricky, looking at the large amount of bondwires and distances covered.

  2. seems like fairchild patent on dual ADC HDR...

  3. Why is it that Arri is basically still unrivaled by other companies? Is it in the inherent features of the sensor or is it just clever in camera color-processing that delivers something that film makers really love? We played around with an Alexa mini for about a month in the off hours and we couldn't break the image or the colors in any way.. it took us minutes to break the image with REDs or Sonys.

    1. Dear Anonymous,

      Did you compare the specifications of Alexa mini with the other cameras.

      How are you sure that no toe/shoulder was applied to the "RAW" output.

      Alexa mini does 3.5K at 30fps. Red Weapon does 6K@100fps and 4K@120fps

      Alexa is using offchip ADCs and is 8.25um pixel size

      Red Weapon uses much smaller pixel.

      Alexa (mini including) has a SWAP (size weight and power) significantly larger than RED/Sony.

      Needless to say who does more processing.

      Like everything camera system is a trade off based on product requirements.

      Different aspects of camera performance appeal to different people.

      Beautiful images are credit to the photographer who knows how to use his/her camera.

      OTOH one can always get images from each camera and claim it broken.


    2. Lol... you're not even worth responding to


All comments are moderated to avoid spam.