No announcement yet.

Metabones Speed Booster

  • Filter
  • Time
  • Show
Clear All
new posts

  • Metabones Speed Booster

    To all folks out there caring to spend some of your knowledge and patience explaining me the following:

    1st question: Metabones claim that Speed Booster increases maximum aperture by 1 stop when mounted between a mirrorless camera and lens and I ask... How?

    I've grown up to believe that every time light passes trough a medium it decreases its velocity, hence aperture. So when light goes trough the Metabones glass element it should loose light, not gaining it.

    Besides that, the Metabones has to deal with an increase in distance. What I mean is that if you mount an M43 lens directly in the BMPCC it will not loose light compared to a Nikon to M43 adapter which will loose light only by the greater lens to sensor distance.

    2nd question: They also claim a MTF increase.

    Well... I know that the several glass elements inside a lens has the function of delivering the best image possible considering resolution, aberration, and so on... Nonetheless, how can Metabones stand by an MTF improvement when lens manufacturers spend years developing lenses like we all know.

    My first thought about it is that it will certainly decrease MTF and not the other way around since it is another element introducing light changes in the image making process.

    3rd question: The increased FOV by a factor of 0.71x.

    This puts BMCC alongside with an S35 sensor (or very close to it) but... We all know how wide angle adapters work and just because they can increase FOV it doesn't mean that it will replicate a bigger sensor (DOF for instance). DOF is related with focal distance to focal plane size and accordingly circle of confusion.

    Since many in this forum are comparing BMCC + Metabones with a S35 sensor, how does an increased FOV will replicate the image that bigger sensor produces (namely DOF)?

  • #2
    Care to read their white paper? It explains all of that nicely, and yes, it does what it claims. At least my version for Zeiss Contax C/Y lenses.


    • #3
      Basically, the Speedbooster shrinks the image circle produced by a lens. This is useful if your camera's sensor has a smaller image circle than your lens produces, like a 135 lens on a S35 (or smaller) sensor, or a S35 lens on something like the BMC. The best analogy I can think of would be a fresnel light. The speedbooster would be like taking the light from full flood to full spot. The light is more intense because it's focused on a smaller area. The speedbooster does the same to the image captured by the lens, taking (for example) a full-frame image, and focusing it down to a S35 frame.

      EDIT: To build on Nomad's post above, here is a link to the white paper (PDF):


      • #4
        Yep, white paper explains it all, and I can verify they aren't lying.


        • #5
          Thank you for all your answers. Thanks Kevin for pointing me directly to Metabones white paper. I'm going to read it tonight and thanks for owners confirmation that the claims are true.


          • #6
            For an EF or F-mount lens adapted to an MFT mount camera, the lens optics will focus the total available light (whatever can enter the front lens element) onto an area that's much bigger than an MFT sensor, so a lot of the light is wasted (hitting the camera internals that are not sensor). The speedbooster simply adds a lens element that focuses that light to a smaller area so that there's a bigger percentage of the total light hitting the sensor. Each photo site on the sensor gets more light exposure for a given amount of time, but technically there's still slightly less total light hitting the camera internals.

            This is the same as frying ants with a magnifying glass. You lose a bit of the total sunlight that goes through the magnifying glass, but to each ant it's way more light.


            • #7
              Originally posted by Kelvin N Nishikawa View Post
              This is the same as frying ants with a magnifying glass. You lose a bit of the total sunlight that goes through the magnifying glass, but to each ant it's way more light.
              Nice analogy


              • #8
                Heres a plain and simple explanantion
                The lens is moved closer to the sensor. Thats the major reason.
                Dustin Uy-Filmmaker