Amira vs Alexa Mini Image

[willvazquez]

Is the Arri Amira image identical to the Alexa mini? I’ve seen some footage where the motion looks a little different and the color not as rich on Amira as Alexa mini. I know both cameras share the same sensor, but I thought maybe the image processing is different. Thanks

[Andreas Berkl]

Dear willvazquez,

yes, as you say AMIRA and ALEXA mini share the same sensor (and color science).

I’ve seen some footage where the motion looks a little different ...

A difference in motion may be explained by the fact that, per default, AMIRA uses EXPOSURE TIME for shutter. ALEXA Mini uses SHUTTER ANGLE:
The setting can be found here: MENU > SYSTEM > SHUTTER UNIT = EXPOSURE TIME (or SHUTTER ANGLE).

Why may this matter? Well, if you are shooting AMIRA with default EXPOSURE TIME it will always be 1/50th of a second (provided the frame rate allows it due to universal laws ...)

If you are shooting ALEXA Mini with default SHUTTER ANGLE = 172.8° (and sensor fps = 24) you will have 1/50th of a second. But if you change fps to say 48 fps, your shutter angle still will be 172.8° (unless you change it). This results in an effective exposure time of 1/100th of a second. Thus motion blur will substantially differ to an AMIRA with 1/50th.

Also please note that AMIRA defaults to 25 fps, ALEXA Mini to 24. So a (tiny) difference in motion portrayal may be noticed out of the box.

... and the color not as rich on Amira as Alexa mini.

That actually is pretty unlikely. Well, no two individual cameras are exactly identical in color reproduction. But when comparing the "average" AMIRA with the "average" ALEXA Mini, they are identical.

Please keep in mind that factors like the actual scene, lens, external filters, lighting directions etc. may have a substantial impact on color reproduction. Even with 2 "ideal" cameras, these factors in real life will result in differences.

Hope this helps.
Best regards,
Andreas Berkl