The best speed boosters for the
Blackmagic Pocket Cinema Camera 4K
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The Pocket 4K's 2.02× Four Thirds sensor is its one real catch: every lens frames tighter than its number. Your 18mm shoots like a 36mm; your "wide" is suddenly a normal. A speed booster fixes both problems at once — it optically shrinks the image circle onto the sensor, so you get a wider field of view and about a stop more light. Here are the three worth buying, and exactly what each one does to your framing.
Metabones Speed Booster XL 0.64×
Built for Micro Four Thirds. The widest option — turns the 2.02× crop into an effective 1.29× (basically Super 35) and adds ~1⅓ stops. The one to get.
Metabones Speed Booster ULTRA 0.71×
The all-rounder. Slightly less wide (effective 1.43×) but flawless optics and the broadest lens compatibility. Choose it if you also use the booster on other bodies.
Viltrox EF-M2 II 0.71×
A quarter the price with autofocus and aperture control. Not quite Metabones sharpness wide open, but astonishing value for run-and-gun and adapted glass.
Same Sigma 18-35mm at 18mm on the Pocket 4K, three ways. The booster doesn't change the lens — it changes how much of the world lands on the sensor.
| Setup | Effective crop | 18mm becomes | Horizontal FOV | Light |
|---|---|---|---|---|
| No booster (native crop) | 2.02× | 36mm eq | 55.5° | — |
| ULTRA / Viltrox 0.71× → | 1.43× | 26mm eq | 73.1° | +1 stop |
| Speed Booster XL 0.64× → | 1.29× | 23mm eq | 78.9° | +1⅓ stop |
The 0.64× XL opens a genuinely wide 78.9° from an 18mm — the difference between "I can't get the shot in this room" and "done." That's why it's the pick.
| Metabones XL | Metabones ULTRA | Viltrox EF-M2 II | |
|---|---|---|---|
| Reduction | 0.64× | 0.71× | 0.71× |
| Effective crop | 1.29× | 1.43× | 1.43× |
| Light gain | +1⅓ stop | +1 stop | +1 stop |
| Autofocus | Yes | Yes | Yes |
| Optics wide open | Reference | Reference | Very good |
| Street price | ~$650 | ~$480 | ~$160 |
| Best for | Widest FOV, best glass | Multi-body owners | Value / adapted lenses |
Do I need a speed booster for the BMPCC 4K?
Not strictly — but on the 2.02× sensor every lens frames tight, and a booster is the cheapest way to reclaim a wide, low-light-friendly image. If you shoot interiors, documentary, or anything cramped, it's close to essential.
Which one should most people buy?
The Metabones Speed Booster XL 0.64×. It's purpose-built for Micro Four Thirds, gives the widest field of view, and pushes the Pocket 4K to a near-Super-35 look. Only step down to the ULTRA if you need one booster across MFT and APS-C bodies.
Will my lenses vignette?
Full-frame-covering EF glass (like the Sigma 18-35 Art or vintage SLR primes on EF adapters) is safe. Some APS-C lenses can vignette through a booster — check each build in the simulator first.