f/0.9 For $300? - FD To E Mount Speed Booster Comparison (Lens Turbo II + Roxsen + Fotasy Review)

IG: To clarify, the speed booster won’t “magically“ change the aperture of your lens. But it will restore the full frame field of view, and concentrates the “full frame image“ on to your APS-C sensor, giving you an extra stop of light. *** The Roxsen Speed Booster cannot focus to infinity due to the glass actually hitting the back of the lens at around 5-10m focus distance (only on selected lenses). This might be a deal breaker for you.