Viltrox Speed Booster Review: Using EF Lenses on the Canon M50
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The quick answer
The Viltrox EF-EOS M2 Speed Booster lets you use compatible Canon EF lenses on a Canon M50 or another EF-M camera. Its 0.71x focal reducer gives a wider view than a normal EF adapter and increases the effective aperture by about one stop.
It is worth considering if you already own full frame EF lenses and want to use more of their field of view. It will not turn an M50 into a full frame camera, and it is not the right adapter for every lens.
Watch the full video
Watch the full video on YouTube
What the Viltrox Speed Booster does
A normal mount adapter holds an EF lens at the correct distance from an EF-M camera. The Speed Booster also contains optics that reduce the projected image, allowing the smaller sensor to capture a wider view.
Make sure you are looking at the EF-EOS M2 version for Canon EF lenses and Canon EF-M cameras. Similar Viltrox adapter names can refer to different mounts. This is not an adapter for Canon RF cameras.
A wider field of view
An M50 has an approximately 1.6x crop factor. With a normal adapter, a 50mm EF lens gives the field of view of roughly an 80mm lens on full frame. With the 0.71x reducer, the field of view is closer to a 57mm lens on full frame.
| Setup with a 50mm EF lens | Approximate full frame field of view |
|---|---|
| Normal EF to EF-M adapter | 80mm |
| 0.71x Speed Booster | 57mm |
The wider framing can be useful indoors, for portraits that include more surroundings, or when a lens feels too tight on the M50. The sensor stays the same size.
About one stop more light
The focal reducer increases the effective aperture by about one stop. An f/2.8 lens works at roughly f/2 through the reducer. That can let you use a lower ISO or a faster shutter speed for the same exposure.
The benefit depends on the lens and the shot. Check sharpness, focus behavior, and the corners of the frame with the exact combination you plan to use.
Background blur and framing
The wider view and larger effective aperture give you different framing and depth of field options. They can be useful for portraits and product shots when you want a blurred background.
Subject distance, background distance, focal length, and aperture still determine the result. An adapter alone does not guarantee better photographs.
Compatibility and tradeoffs
- Lens mount: Choose compatible full frame Canon EF lenses. Native EF-M lenses mount directly to the camera and do not use this adapter.
- Camera mount: The camera must use EF-M, such as the M50, M50 Mark II, M5, or M6.
- Weather protection: Do not rely on the adapter as a sealed connection. Keep it out of rain and snow.
- Autofocus: Test your exact lens and firmware combination before relying on it for an important shoot.
- Cost: In the original video, I discussed it at about $150. Compare current prices before deciding whether it makes sense for your existing lenses.
Should you buy one?
I would consider the Viltrox EF-EOS M2 if I already had compatible EF lenses and wanted a wider view or more light on an M50. If you mainly use native EF-M lenses, it does not solve a problem for that kit.
The item to look for is the Viltrox EF-EOS M2 0.71x Speed Booster for Canon EF to EF-M. Confirm both mounts and the lens compatibility before buying.