ARRI ALEXA Mini LF Ready to Shoot V-Mount Set (LPL) - Manual (Page 53)

Main Parameters 53
14.3 Shutter
Changing the Shutter
1. Select HOME > SHUTTER .
The shutter list is displayed.
2. Select a shutter value from the list or ADD a custom shutter value to the list.
3. Set the desired shutter value.
Adjusting the Shutter for Filming a Monitor
1. Set the shutter unit to Shutter Angle .
2. Go to HOME > SHUTTER > ADD.
3. Select the third digit (single degrees).
4. Adjust the shutter value until the monitor image flickers the least.
5. Select the fourth digit (sub-degrees).
6. Fine-adjust the shutter value until there is no more flicker visible.
7. Press SET to add the shutter value to the list.
Shutter Unit
The camera offers to set the shutter unit.
1. Select
MENU > System > Shutter Unit .
Two options are available:
Shutter Angle Converts exposure time into the angle of a virtual rotating mirror shutter as
in film cameras. A fixed angle creates varying exposure times with varying
frame rates. You can set angles from 5.0 to 356.0 degrees.
Exposure Time Shows the effective sensor exposure time. With varying frame rates, it re-
mains identical and can be set from 1/1 to 1/8000 seconds.
Note: Maximum exposure time with a given frame rate is 1/fps, with a lim-
it of 1/1 seconds. When the selected exposure time is no longer possible
because you changed the frame rate, the camera uses the longest expo-
sure time possible. For example, if you configured 1/25 s at 25 fps and you
change the sensor fps to 50, the camera will use 1/50 s.
For a constant exposure time over a range of used frame rates, set it to
1/(highest used frame rate).
2. Set the desired shutter unit.
Note: The camera sensor is optimized for exposure times shorter than 1/24 s and image artifacts like
individual overexposed pixels can appear when using longer exposure times.
14.4 Exposure Index
The Exposure Index (EI) is the applied sensitivity of the camera. The ALEXA Mini LF has a base
sensitivity of 800 ASA. This means that the dynamic range is almost evenly distributed above and
below neutral gray with low noise in the shadows and clean, smooth clipping behavior in the highlights.
Due to its high dynamic range, the camera’s sensitivity can be set from 160 to 3200 ASA in steps of 1/3
stops while maintaining high image quality.
Applying the exposure indexes at the extremes of the range will nonetheless have an influence on the
images. At low exposure indexes, such as 160 ASA, the dynamic range below neutral gray increases,
reducing noise even further. At the same time, the dynamic range above neutral gray is slightly