Blackmagic Design URSA Mini Pro Shim Kit

Blackmagic Design URSA Mini Pro Shim Kit

The Blackmagic Design URSA Mini Pro Shim Kit is a specialized calibration set used to adjust the flange focal distance (the distance between the lens mount and the sensor) of your camera.

In 2026, it remains an essential tool for cinematographers and DPs who need to ensure their lenses perform with 100% optical accuracy, particularly when shooting at extreme resolutions like 12K where even a microscopic misalignment can cause soft images or inaccurate focus marks.

Core Functionality

• Back Focus Calibration: Shims are used when a lens fails to hit "infinity focus" correctly or when a zoom lens does not stay in focus throughout its zoom range (parfocal behavior). By adding or removing these ultra-thin shims behind the lens mount, you move the lens slightly closer to or further from the sensor.

• Precision Tolerances: These shims are precision-cut to maintain the electronic connection between the camera and the mount, allowing lens metadata and electronic iris control to pass through without interruption.

• Interchangeable Mount Support: This kit is designed to work across all replaceable URSA Mini Pro mounts, including EF, PL, B4, and F mounts.

What’s Included in the Box?

• 9 x Precision Cut Shims: A set of shims in varying thicknesses, allowing for minute, incremental adjustments to the mount's depth.

• 1 x Baffle Tool: A specialized tool designed to safely remove and install the internal light baffle (the black plastic ring behind the mount) without damaging the sensor or the camera’s internal components.

Technical Specifications

When Should You Use This?

You should use the shim kit in the following scenarios:

1. Changing Mounts: Whenever you swap from an EF mount to a PL or B4 mount, you should check the back focus.

2. Inaccurate Focus Marks: If your lens is physically set to 10 feet but the subject at 10 feet is blurry, your flange distance is off.

3. Infinity Focus Issues: If your lens "bottoms out" and cannot reach sharp focus on distant objects (like a mountain range).

4. Zoom Drifting: If you focus a zoom lens at the telephoto end, but the image becomes blurry as you zoom out to wide-angle.

Operational Insight (2026)

In 2026, "shimming the mount" is considered a standard part of prep for any professional production. Because thermal expansion can slightly alter camera bodies over years of use, a quick back-focus check with this kit ensures that you aren't fighting your equipment on set.

Pro Tip: Always perform your shimming in a clean, dust-free environment. Since you are removing the lens mount and exposing the area near the sensor, any dust that enters could end up on your OLPF or sensor glass, appearing as spots on your 12K footage.