Arri Alexa Mini Digital Dust, Cosmic Radiation and Yoga

[mahadevan]

Hey All,

I just finished shooting a series of yoga workouts on a black background with the Alexa Mini (2 Camera Shoot). About a month after shooting, the editor noticed a number of white specks throughout the footage (both A and B camera). The white specks would randomly appear in a one frame and disappear in the next (no consistency to area of frame). After speaking with Arri, they believe that this is an environmental issue caused by cosmic radiation. We've currently found about 15 specks within 3 episodes of shooting (which were shot on 3 different days). See below for a couple of samples with the specks. Let me know if you've seen anything like this before. We're going to be shooting the next round in a week and are trying to prevent this issue.

(Update:) I have recently tested different Alexa Minis in a separate location and have had the same issues.

Best,

Chad Mahadevan

[Andreas Berkl]

Dear Chad,

what you see is unfortunately a "normal" issue inherent to digital cameras in general and there is practically nothing that you can do prevent it.

Snip from ALEXA Mini user manual:
Single Frame Spots of Various Shape – also known as “Digital Dust” or “White Flecks”
Natural and/or artificial radiation may cause a “false exposure” on the image sensor. The shape of these spots may vary from dots to lines or other, sometimes irregular shapes. These spots occur in random locations of the image, last only for a single frame and are more visible in dark images. This is a principle issue of all image sensors and not a malfunction.

and citing from a SONY user manual:
White flecks
Although the CMOS image sensors are produced with high-precision technologies, fine white flecks may be generated on the screen in rare cases, caused by cosmic rays, etc. This is related to the principle of image sensors and is not a malfunction.

Best regards,
Andreas Berkl

[Jan Heugel]

Double-posting... this is a camera independent topic.

See same topic within the ALEXA:
https://forum.arri.com/viewtopic.php?f=46&t=104

Thanks,
Jan