Blackmagic Design URSA Manual Del Usuario página 45

Shimming the PL Mount
45
Removing and replacing the PL Mount
Step 1.
Place Blackmagic URSA on a solid, clean bench
top and remove your lens or dust cap. The glass
filter covering the sensor will be exposed for the
duration of the shimming process, so it's important
to keep the filter as clean as possible. Be careful not
to touch the filter while shimming the PL mount.
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Shimming the PL Mount
What is a Shim?
Blackmagic Shims are thin disks of varying thickness that let you make fine adjustments to the distance
between your PL lens and Blackmagic URSA's sensor. This distance is commonly known as the flange focal
distance, or back focus, and can change slightly due to variables such as lens age and the environmental
conditions of your shoot. The PL mount is designed so you can easily adjust the back focus using shims.
Shims are placed between the PL mount and the camera body so the distance from your subject to the
sensor matches the focus marks on your lens. Your Blackmagic URSA is supplied with a 0.50mm shim already
installed. You can purchase shim sets of varying thickness from your local Blackmagic Design reseller. Use
shim thicknesses depending on your back focus requirements.
To shim your Blackmagic URSA's PL mount you'll need a torque wrench able to accurately set a maximum
torque of 0.45Nm, with 2.0mm and 2.5mm hex key drivers.
Step 2.
Remove the six PL mount screws using the 2.5mm
hex key. You may need to occasionally rotate the
PL locking ring clockwise or counterclockwise to
access the screws.
Step 3.
Carefully lift the lens mount away from the camera
body. Keep the screws safely located close to the
lens mount.