SKU: 44122253502

Blackmagic Design Spares - Camera URSA Broadcast - B4 Mount

Sale price$5040.96 Regular price$5601.07
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Description

Blackmagic Design Spares - Camera URSA Broadcast - B4 MountThe Blackmagic Design Spares Camera URSA Broadcast B4 Mount is a precision engineered replacement lens mount designed specifically for the URSA Broadcast and URSA Broadcast G2. Because B4 lenses are the standard for electronic news gathering (ENG) and studio production, this mount is a critical interface that bridges high end broadcast optics with the URSAs digital sensor. Optical and Mechanical Precision The B4 mount is significantly more complex

The Blackmagic Design Spares - Camera URSA Broadcast - B4 Mount is a precision-engineered replacement lens mount designed specifically for the URSA Broadcast and URSA Broadcast G2. Because B4 lenses are the standard for electronic news gathering (ENG) and studio production, this mount is a critical interface that bridges high-end broadcast optics with the URSA’s digital sensor.

Optical and Mechanical Precision

The B4 mount is significantly more complex than a standard passive mount (like an EF or F mount). It features integrated optics designed to correct for the spherical aberration introduced by the three-color prism found in traditional B4 cameras.

  • Spherical Aberration Correction: Since B4 lenses were originally designed for 3-sensor prism cameras, using them on a single-sensor camera like the URSA requires corrective glass. This mount includes high-quality optics that ensure the image is sharp across the entire sensor.

  • Rugged Locking Mechanism: Features the classic "breech-lock" ring, allowing operators to secure heavy ENG zoom lenses with a rock-solid connection that prevents "lens sag."

Electronic Integration

The B4 mount spare is not just a piece of metal; it is an electronic bridge.

  • 12-pin Hirose Connection: The mount assembly works in tandem with the 12-pin broadcast connector on the side of the URSA chassis. This allows the camera to power the lens and provides the operator with control over iris, zoom, and start/stop recording via the lens handgrip.

  • Lens Data Metadata: It facilitates the transfer of lens metadata (f-stop, focal length) directly into the Blackmagic RAW or ProRes files for post-production and VFX use.

Why You Might Need a Replacement

  • Optical Scratches: Since this mount contains internal corrective glass, any scratches or fungus on that rear element will directly impact image quality.

  • Mechanical Wear: The breech-lock ring can become loose or "gritty" over years of use in the field, leading to a lens connection that isn't perfectly light-tight.

  • Electronic Pin Damage: While the 12-pin connector is on the camera body, the communication logic for the lens is tied to how the mount is seated. If the mount is warped due to a drop, the electronic connection may become intermittent.

Key Features

  • Genuine OEM Spare: Guaranteed to maintain the correct flange focal distance (back focus) for B4 optics.

  • Shim Kit Included: Usually ships with a set of precision shims to allow for fine-tuning of the back focus, ensuring the lens stays in focus throughout the entire zoom range.

  • Durable Construction: Made from high-strength stainless steel and aircraft-grade aluminum.


Technical Installation Note

Replacing a B4 mount is a "clean-room" task that requires precise calibration:

  • Sensor Protection: When the mount is removed, the camera's sensor is completely exposed. Perform the swap in a dust-free environment and keep the sensor protected with a body cap whenever possible.

  • The Shimming Process: After installing the new mount, you must check the "back focus." If the lens is sharp at the wide end but soft at the telephoto end (or vice versa), you will need to add or remove the included shims behind the mount.

  • Screw Torque: Use a high-quality Torx or Hex driver (as specified by the current revision) and tighten the mounting screws in a "star pattern." This ensures the mount is perfectly flush against the camera body.

  • Avoid Fingerprints: Do not touch the rear corrective glass element. If you do, clean it only with professional lens cleaning solution and a high-quality microfiber cloth.

Are you seeing softness in your image that suggests the internal glass is damaged, or are you looking to convert an URSA Mini (EF/PL) into a Broadcast-ready rig?

Shipping Notes
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SKU: 44122253502

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4.5 ★★★★★
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Product Reviews
F
Fred
Natrona Heights, US
★★★★★ 5
Stable, flexible in deployment configuration, creates true privacy and looks great.
Size: 3 Panel 12FT W
This is the second room divider panel I have installed, and there are several features about this one that I like much better than my older one. The fact that there are no gaps and that the material is thicker means you get more privacy or more hiding power, if you wish. My older divider has vertical spaces between each of the panels and the panels are half as wide as the Siebwin panels, so there are many vertical spaces. The Siebwin divider really creates privacy. Another feature that I really appreciate is that the legs are wider and stand off from the floor. On my older one the legs are flat and they're rather awkward to adjust because they create more drag on the floor. The feet on the older one also loosen if you turn them counter clockwise, so adjustments of configuration that require the feet to be moved are more complex. The older divider also must be deployed in a zig-zag fashion because he feet are not as wide, but this new one can be deployed and stable in a straight, an "N" shape or an arc. They are both the same length, but because the older one must be use in a zig-zag deployment it doesn't reach to the length of the new one. The Siebwin divider definitely costs more at $103.48, but it sports several features and advantages over the other brand, so it does a better job and is worth the extra cost.
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Reviewed in the United States on May 25, 2026
C
Computer
Charlottesville, US
★★★★★ 4
Easy to assemble, does the job, material is shiny nylon and shows creases, minor defects, sloppy
Size: 3 Panel 12FT W, Size: 3 Panel 12FT W
The Siebwin room divider is a good idea, and for the price, it mostly delivers on the intended functionality. I ordered the 12 foot, 3-panel version mainly to hide an unfinished basement storage area that had become an eyesore. It works well for that purpose and gives the space a cleaner appearance without spending the kind of money that more decorative dividers or custom partitions cost. If you need something temporary, portable, or mainly functional, this is a viable option. There are a few limitations that became obvious during setup and use. The first thing I noticed was that the weld quality on some of the metal poles is fairly sloppy. Once the cover is installed, you do not really see it, but up close, it does not look especially refined or professional. The blackout material also is not a matte canvas style fabric as I expected. It has more of a shiny nylon appearance, and the creases are fairly visible. Being that it’s more of a nylon, I’d be hesitant to try steaming it to remove the creases. However, the creases do not matter if you are using it in a basement, dorm, or shared room, but for photography, video work, or a professional office setting, the appearance could be disappointing. The fabric is thick enough, though. It blocks visibility well enough, but strong light behind it still shows through to some extent, nothing deal-breaking. Also, my fabric appeared to be slightly defective. The hook and loop strip on one of the bottom sections was off-center and couldn't be totally attached because it was lined up with one of the legs. I originally hoped to use this as a video backdrop, but I will probably end up replacing the fabric with a proper green screen or canvas material while continuing to use the frame itself. For now, it does a good job of covering my basement junk. Assembly was actually easier than I expected and took roughly 15 to 20 minutes. The longer vertical poles are tethered together similarly to tent poles, which made setup straightforward and fairly intuitive. The shorter horizontal pieces slide and snap together to the top and bottom of the vertical assembly. After each section is assembled, the divider panels connect together with metal plates and two knurled screws (at the top and bottom), so no tools are really required. A few screws were difficult to start because paint had gotten into the threads, but once they caught, they tightened down normally. The feet install with similar knurled fasteners and help keep the divider reasonably stable. One thing to watch for during setup is the fabric orientation. There is one arrow indicator in the middle of the fabric to indicate up. However, if you need another indicator, the smaller hook and loop strip goes on the bottom while the longer strip goes on top. I realized mine was upside down right before finishing and had to redo it. I wasn't difficult to redo, despite the defect in mine. The overall design is practical and easy to move around. I do like that the panels can fold and bend into different shapes depending on the space. The widened feet help stability, although when trying to stretch the fabric tight, I noticed the poles sometimes wanted to overlap slightly at the joints. Tightening everything helped somewhat, but it still happened occasionally. The divider feels adequate for normal indoor use, though I would not expect premium durability or luxury-level fit and finish at this price point. The entire device can also be easily disabled and stored in a tote if you need it completely out of the way. It comes with assembly instructions, but even if you didn’t have them, it’s easy to build without them (save a mistake or two). In terms of value, I think the Siebwin divider mostly matches its price. Around $100 gets you a large freestanding partition with decent usability and easy assembly, but there are compromises in materials, appearance, and refinement. The defects are also off-putting, but hopefully you won't have them. Higher-end room dividers can easily cost two or three times more, so some of the tradeoffs are expected. I also noticed cheaper alternatives online, but based on the quality here, I suspect those would probably have even more issues. For practical home use, temporary privacy, hiding storage areas, or separating shared spaces, this is a good option as long as expectations stay realistic.
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Reviewed in the United States on May 18, 2026
T
Trendy Tales
Omaha, US
★★★★★ 3
Works well but takes up more space than expected
Size: 2 Panel 8FT W, Size: 2 Panel 8FT W
This room divider does the job for creating a little extra privacy and was easy enough to set up. The panels feel decent quality and the wider feet help keep it more stable than some cheaper screens I’ve tried. My only issue is that it takes up a bit more room than I expected, especially with the feet sticking out. It’s still portable and folds away nicely, but definitely measure your space first. Overall it works well for separating a room or blocking off an area temporarily. i wish it came in other colors
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Reviewed in the United States on May 26, 2026
K
Katrina Rhodes
Los Angeles, US
★★★★★ 5
Nice divider, serves it's purpose well!
Size: 3 Panel 12FT W
This room divider worked out very well for what I needed. I wanted a simple way to create a little more privacy and separation in a larger room without doing anything permanent, and this divider was an easy solution. The panels provide good coverage, and the black color gives it a clean, modern appearance that blends in nicely with different décor styles. Assembly was fairly straightforward, and once set up, the wider feet helped keep the divider stable on the floor. I was especially happy with how flexible the panels are to arrange. You can keep it mostly straight, angle it around furniture, or create a more enclosed private space depending on the layout you need. The material allows light to filter through slightly while still offering a noticeable sense of privacy. I’ve used it for separating a workspace area, but it would also work well in bedrooms, apartments, dorms, studios, or shared living spaces. Another plus is that it can be folded and moved without too much effort when you want to change the setup. Overall, this divider delivers a good balance of functionality, portability, and appearance. It’s a practical option for anyone needing temporary room separation without installing permanent walls or curtains.
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Reviewed in the United States on May 26, 2026
J
Jamie K.
Lake Worth, US
★★★★★ 5
Perfect for Adding Privacy to a Piano Studio
Size: 2 Panel 8FT W, Size: 2 Panel 8FT W
I Ordered the 2 Panel version which is way too big for my needs... that's on me. So keep in mind that the picture shows a fabric made for two panels only being used on one and hence it is not pulled tight; it would pull tight and not be so wrinkly if it was set up properly as two panels. The metal pools that make up the panels seem to be well made, stable, and of good quality. They were very easy to put together and they stand up tall with plenty of height. The appearance of it with the fabric on it isn't as elegant as it could be, but it still looks good enough. The material is plenty solid, not allowing light through it, and thereby making a solid barrier. I am using it to block the view out the studio door when a student is sitting at the piano to avoid distractions from the hallway. It will allow a student to enter the studio with our distracting the student who is at the piano.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 18, 2026

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