need help adapting a helios 44-2 to gh4 with speedbooster In: Cameras Posted August 18, 2019 If you are based in the EU I have an EF-mount Zhong Yi lens turbo II (speed booster clone without electronics) that I could sell for 60€. In any case if you're just planning to use m42-lenses it would be cheapest to use a RJ/Jinfinance or Zhong Yi lens turbo, as you don't need any electronics in there. They are both good, supposedly more or less on par with metabones, just check reviews on the internet. In my experience the various speed boosters all work well on m4/3 as the corners are much better on those sensors than on aps-c. The only one I've tested that has been significantly worse than the others is the Kipon Baveyes.