Shimming Lens Mounts
What is a Shim?
Shims are thin disks of varying thickness that let you make fine adjustments to the distance
between your lens and URSA Broadcast'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.
URSA Broadcast Shim
Shims are placed between the lens mount and the camera body so the distance from your
subject to the sensor matches the focus marks on your lens. These are most commonly used
for PL lenses. These cine lenses are manually focused and have very accurate focal distance
markings on their barrels. Shims are also used for URSA Broadcast's interchangeable
lens mount.
Your Blackmagic URSA Broadcast is supplied with a 0.10mm shim already installed.
The Blackmagic URSA Mini Pro 4.6K Shim Kit contains additional shim sets of various
thicknesses, and can be purchased from your local Blackmagic Design reseller. A set of shims is
also included with all mount kits and are compatible with URSA Broadcast. Use shim
thicknesses depending on your back focus requirements.
Blackmagic URSA Mini Pro Shim Kit
Your URSA Broadcast camera ships three shims, a 0.10 mm plastic shim and 0.10 and 0.50 mm
metal shims. These shims set the proper focal distance for your URSA Broadcast camera's B4,
EF, and F mount lenses. Very occasionally, you will need to use additional shims to suit
PL lenses that require very specific clearances to maintain accurate focus marks. Blackmagic
URSA Mini Pro Shim Kit includes the following additional tools. Other thicknesses are included
in the kit in case you need to re-shim your camera to suit PL lenses that may require slightly
different clearances to maintain accurate focus marks.
The shim kit includes:
1x Baffle tool
Use the baffle tool to loosen or tighten the PL baffle when
removing or attaching the PL mount to your URSA Broadcast.
1 x Shim set
The shim set includes the following thicknesses:
0.50mm
0.30mm
0.20mm
0.18mm
0.15mm
0.12mm
0.10mm
0.05mm
0.025mm
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Shimming Lens Mounts