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BMPCC with speedbooster and Sigma 18-35? Actual focal length? Electronic interaction?

Discussion in 'Blackmagic Design Cameras' started by magellan, Jun 17, 2015.

  1. magellan

    magellan Mu-43 Rookie

    22
    May 4, 2014
    If I used the BMPCC metabones speedbooster with the Sigma 18-35, would the lens become an 10.5-20.3mm f/1.0? Because that is pretty wide. Also, is the Nikon mount electronic and interact with the aperture or only the EF mount?


    thanks so much
     
  2. tkbslc

    tkbslc Mu-43 Hall of Famer

    Yes, Thats how the math works out. They even have a table at the bottom of the page for the adapter stating so:

    http://www.metabones.com/products/details/MB_SPEF-BMPCC-BM1

    Keep in mind that the BMPCC has a 3x crop factor, so you end up back at 30-60mm FF equivalent (At F1.0!!). That is like a 15-30 on regular m4/3 camera.

    If you want really wide and fast, the Tokina 11-16 is a good one. You'd be at 6.4-9.3mm f/1.6.

    You may want to email Metabones on the Nikon vs Canon mount adapter functional differences.
     
  3. magellan

    magellan Mu-43 Rookie

    22
    May 4, 2014
    Okay, so it will really be 30-60mm on the BMPCC with the speedbooster, correct?
     
  4. tkbslc

    tkbslc Mu-43 Hall of Famer

    It will be 30-60mm in 35mm film equivalent terms.
     
  5. magellan

    magellan Mu-43 Rookie

    22
    May 4, 2014
    Awesome...and that is because the bmpcc makes the FOV 35mm? Just making sure!
     
  6. tkbslc

    tkbslc Mu-43 Hall of Famer

    People often compare systems with different sensor sizes by relating them back to 35mm film equivalent focal lengths. This is because depending on the sensor size, a given focal length will give a different view. That's what I was doing here (and what metabones' chart on their product page does). So that lens would have the same view that a 30-60mm zoom on a film camera would have had. It can get a little confusing comparing systems with different sensor sizes.

    Are you currently using the BPMCC? If so what other lenses do you use with it? Maybe comparing to those would be more productive. What camera systems have you used?
     
  7. magellan

    magellan Mu-43 Rookie

    22
    May 4, 2014
    Thanks for being so helpful! I am actually buying a BMPCC today, upgrading from my M43 Panasonic GH3. The glass I used on my GH3 was a set of Rokinon Primes (16mm, 35mm, and 85mm). I am looking to get rid of the 16mm and 35mm for the Sigma.
     
  8. tkbslc

    tkbslc Mu-43 Hall of Famer

    You are welcome, it's no problem.

    So compared to your GH3, the BMPCC has a smaller sensor, which means the same focal lengths will be less wide on the Black Magic. You will need a 10mm on the BMPCC to give you what 16mm did on the GH3 and you'll need a 23mm to give you what the 35mm gave on the GH3. So the 10-20mm you get when using the Sigma with a speed booster should be right about there.

    Also, your 85mm will seem about 50% longer focal length when using it on the BMPCC. If you want it to be the same, you could swap to a DSLR mount one and use the speed booster on it, or switch to a 50mm lens without the speed booster.

    Good luck with the new camera.