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Seriously need your help and advice

Discussion in 'Adapted Lenses' started by quinlan, Aug 1, 2011.

  1. quinlan

    quinlan New to Mu-43

    Jul 31, 2011
    Hello all,
    I'm new to MFT cameras - in fact I'll be when I receive the GH2 Panasonic I ordered - and I'd appreciate your help on a couple things.

    When I bought my GH2 body, which is intended for film work only, I was counting on using old Nikkor primes I have, namely a 55mm 3.5, a 105mm 2.8 and a 105mm 2.5.
    Now, if I understand correctly, a 55mm 3.5 is on a MFT camera actually equivalent to 110mm 7.0, which is not exactly wide or fast, so maybe I'll have to buy new primes after all. Is what I just said more or less right?

    So here's what I'd need to know: what kind of lenses should I get for movie work with a MFT camera? Do you need especially big aperture? What is the best thing I could do?
    I looked up some wide angle lenses and found the following:
    1 Sigma 20mm 1.4 Olympus or Nikon mount
    1 Sigma 30mm 1.8 Aspheric
    1 Nikon 35mm 2.0 Afd
    1 Tokina 28mm 2.8 Ais
    1 Canon 35mm 2.0 Fd mount

    Are those suited to what I intend to do with that GH2 (that is, again, movies, with preferably wide angle shots and considerable movement, low light sometimes, etc)? Or maybe you have suggestions as to better alternatives?

    Thank you.
  2. songs2001

    songs2001 Mu-43 Top Veteran

    Jul 8, 2011
    If you want wide and fast, I'll look into mounting C mount lenses, GH2 has a crop mode which lets you use these lenses without much vignetting.
    • Like Like x 1
  3. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    No, that's incorrect. Your lens speed is the same on MFT as it is on any other camera. The f/3.5 aperture remains at the same speed, but the focal length is effectively doubled for Field of View. So your 55mm f/3.5 is the working equivalent of a 110mm f/3.5, and your 105mm primes are the working equivalent of 210mm f/2.8 primes. Most likely your f/2.5 prime is probably an f/2.8 re-branded for differentiation. ;) 

    Your DOF is increased on MFT though, so your f/2.8 lens will give you the DOF of an f/5.6 lens if I'm correct. That means you'll get a lot more in focus without having to sacrifice any lens speed by stopping down. f/5.6 DOF with f/2.8 lens speed is a nice bonus for fast action shooting, and especially with manual focus. :) 

    Songs is correct about C-mount lenses giving you a broad range of both wide and fast. I like fast lenses but I'm not much into wide-angle so I can't help you there. I prefer the high quality of rangefinder lenses over the cheaper cine lenses, though. Both offer short flange distances so will keep your MFT system small and compact.
    • Like Like x 3
  4. Firstly, in terms of exposure, there is no equivalence factor. f/2.8 is f/2.8 regardless of sensor size.

    The concept of doubling the focal length and halving the aperture value is related to the changes in angle-of-view and depth-of-field caused by using a smaller sensor than the "full-frame" standard.

    The diagonal (longest) measurement of a Micro 4/3 sensor is half that of a full-frame sensor. The sensor records only half the angle-of-view of a full-frame lens. This is where the 2x equivalent focal length originates.

    Angle-of-view of a 50mm lens on a Micro 4/3 camera = Angle-of-view of a 100mm lens on a full-frame camera.

    The aperture equivalence originates from the effect on depth-of-field due to focal length. Even though the 50mm lens in the example above gives an equivalent field-of-view of a 100mm lens, it retains the optical properties (including depth-of-field) of it's quoted focal length. Therefore it needs a larger aperture to achieve similar depth-of-field effects as a 100mm lens on a full-frame camera.

    So, the theory goes that a 50mm lens @f/2.8 on a Micro 4/3 camera should give the same angle-of-view AND depth-of-field as a 100mm lens @ f/5.6 on a full-frame camera. Whether the 2 stop equivalence in aperture is in fact the correct number is something that I can't confirm or deny.
    • Like Like x 3
  5. Ronghualu

    Ronghualu New to Mu-43

    Aug 17, 2011
    did your lens ideas work for video?
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