Metabones Speed Booster - allows you to use full frame canon lenses on your M43. I was using this briefly with a GH5 with no issues, although you might need to update firmware on the adapter and the lens to get the most out of it. Just a warning, if you plan on using the with the popular 18-35 or any other APS-C you will have a vignette around the edges, this is for full frame lenses. I ended up switching to native lenses so it's sat on my shelf unused and it fantastic condition.
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Selling my Metabones Speed Booster XL 0.64x, designed to mount full-frame Canon EF lenses onto Micro Four Thirds cameras—such as the Panasonic Lumix DMC-GH7. • Advanced 6-element optical design for exceptional performance, even at apertures as wide as f/0.8 • Reduces the Micro Four Thirds crop factor from 2.0x to 1.28x, effectively transforming your setup into APS-H format • Increases light transmission and field of view • Constructed from durable yet lightweight aluminum alloy A high-quality, precision adapter—message me with any questions or for more details!
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It increases the field of view by 0.71x, which is equivalent to cropping by 1.4x. It also increases the maximum aperture by 1 stop, which can be helpful in low-light conditions. It's a high-quality product that will help you take your photography and videography to the next level.
eBay