Understanding the Impact of a Speed Booster on Aperture and Focal Length

by | Sep 6, 2018 | Gear and Reviews

In this blog, I’m delving into the intricacies of how a speed booster affects aperture and focal length, specifically focusing on my recent experience with the Metabones Speed Booster for my GH5.

What is a Speed Booster?

A speed booster is an adapter that enables you to mount different lenses onto your camera. It essentially ‘speeds up’ a lens by increasing the amount of light it lets in and also affects the lens’s effective focal length.

The Metabones Speed Booster

I recently acquired the Metabones EF-MFT Mount T Speed Booster ULTRA 0.71x for my GH5. This particular model is quite an investment, costing around £450 used (around £700 new). But it’s a game-changer for anyone looking to expand their lens options, especially for micro four-thirds cameras like the GH5.

Product Links:

Benefits of the Speed Booster

  1. Focal Length Adjustment: It makes a lens wider than it would be normally.
  2. Increased Light Sensitivity: Allows more light into the sensor, effectively ‘speeding up’ the lens.
  3. Mount Versatility: Enables mounting of EF mount lenses onto a micro four-thirds camera body.

Real-World Implications

Focal Length Calculation

To understand how a speed booster affects focal length, let’s take the Canon 50mm F1.4 lens as an example:

  1. Multiply the lens’s focal length by the magnification factor of the speed booster (50mm x 0.71 = 35.5mm).
  2. Then, multiply this result by the crop factor of your camera’s sensor (35.5mm x 2 for micro four-thirds = 71mm).

Aperture Calculation

Similarly, for aperture:

  1. Multiply the lens’s aperture by the magnification factor (F1.4 x 0.71 = F0.99, rounded to F1).
  2. Adjust for the sensor’s crop factor (F1 x 2 = F1.9 as a full-frame equivalent).

Conclusion

The Metabones Speed Booster is a powerful tool for filmmakers and photographers using micro four-thirds cameras like the GH5. It not only expands your lens choices but also enhances low-light performance and depth of field control. The calculations for focal length and aperture may seem complex, but they’re essential for understanding the true capabilities of your lenses with a speed booster.


Whether you’re looking to utilize old lenses or maximize your camera’s potential, a speed booster like the Metabones can be an invaluable addition to your gear. If you have any questions or experiences with speed boosters, feel free to share!

Happy shooting!

Stay Connected

I'm Will Chidlow, passionate about creating visually captivating content that tells a story. Whether it's through video production, photography, or content creation, I'm here to help you share your ideas with the world. Learn more about my work. Follow me on Instagram and don’t forget to subscribe to my YouTube channel.

Check out my kit

For a comprehesive list of all the equipment I regularly use for filmmaking, photography & content creation.

View kit list

Let me help you tell your story

Whether you need a one-off “about us” video for your website or 40+ Instagram reels ready to roll, I’m your guy. Contact me and lets grow your ideas.

Join the community

Over on my YouTube channel is where the real party is, come and join the fun.

Related posts