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aperture m43 vs FF

Discussion in 'Open Discussion' started by Kilauea, Nov 10, 2012.

  1. Kilauea

    Kilauea Mu-43 Regular

    110
    Jun 9, 2012
    Canada
    Nicolas
    First of all I know this kind of topic can get pretty heated. I just want to clarify my understanding of things, so please leave your emotions aside and answer with your head.

    Say I have an olympus 45mm f1.8 and I am shooting at f1.8 and I compare it with a FF lens which is a 90mm and I shoot at f1.8. Both cameras are used in the very same environment and use the same ISO value. Would the following affirmation be correct.

    1. Both cameras would require the same shutter speed in order to have the same exposure.
    2. The FF camera would have a shallower DOF whereas the m43 camera would have a DOF equivalent to the FF if the aperture value was set to f3.6 (granted the shutter speed would be adjusted accordingly).

    Once more, I am not trying to start a debate, I just want to make sure my understandings of things on this matter are correct.

    Thanks.
     
  2. Amin Sabet

    Amin Sabet Administrator

    Apr 10, 2009
    Boston, MA (USA)
    You are correct on both counts. The only camera settings which affect exposure are the f-number and shutter speed. ISO affects brightness (apparent exposure) but not exposure.

    The only slight issue with your statements is that you are using "aperture" to mean the f-number, whereas the f-number is more correctly called a "relative aperture" (aperture relative to focal length).

    Sent from my Galaxy Nexus using Mu-43 App
     
  3. MAubrey

    MAubrey Photographer

    Jul 9, 2012
    Bellingham, WA
    Mike Aubrey
    You've got it. That's is.

    Most of the heated stuff starts when people start talking about 100% equivalent pictures...which would required the FF to be stopped down to 3.6 and the ISO then upped by two stops:

    OM-D ISO200 45mm f/1.8
    D600 ISO800 90mm f/3.6 (though there is no Nikon 90mm, though, perhaps a Voigtlander 90mm f/3.5 in F-mount)

    The difference in the size of the circles of confusion change things every so slightly, too, but that's details.

    Assuming the sensors are equally efficient, they should have the same amount of noise, too. Or so I'm told. I've only shot 135 format in film. And I would expect that's the case with the OM-D and the D600 with their Sony sensors of the same generation.

    By extension, it's impossible to have equivalent photos where the FF sensor is less efficient. DxO marks the original Canon 5D as very similar in sensor quality to the OM-D...which would mean that you'd get two stops more noise for an equivalent image or a narrow DOF for the same amount of noise.
     
  4. With_Eyes_Unclouded

    With_Eyes_Unclouded Mu-43 All-Pro

    Apr 17, 2012
    Vassilios
    Because in such discussions the prevailing argument "for" FF is shallow DOF, I'm feeling sometimes like the needle is stuck on the same spot...

    Does anyone believe there is always the same camera to subject or background from subject distance? Because these contribute more to shallow DOF than the aperture/sensor size relation. It seems like these arguments come from people that shoot the same subject again and again... hmmm... test charts perhaps? I wonder... :rolleyes:

    Apart from that, the relative strength of a FF camera regarding ISO noise is, again, subjective to application. I believe we have to always compare (if we have to compare, because it's a choice after all) complete systems. E.g. let's take a FF camera (say a 5DMk3) with a 24-70 f/2.8 lens (non-stabilized) vs a OM-D or GH3 (best sensors so far for :43:) with the Panasonic 12-35 (which has stabilization). Given a low light condition, the Canon may need to up the ISO 2-3 stops to obtain a steady hand-held shutter speed. The :43: camera can manage the same shot at the lower ISO setting. As a result, the advantage of FF on ISO noise is diminished. This is just a (simplistic) example but goes to show that it's the whole package and the application that matter and not any off the shelf technical dogma.

    As another example, current MF digital cameras suck at high ISO; but their relative strength lies in "controlled" shooting environments where, in ISO up to 800, they kick the living daylights out of any current FF camera for resolution and color depth. Oh, and need I get nasty and mention shallow DOF? :tongue:

    All established camera systems have their relative strengths and weakneses; I really can't understand why we have to compare them to each other and not examine if they are suitable for the project at hand. :smile:
     
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  5. Chrisnmn

    Chrisnmn Mu-43 All-Pro

    Apr 26, 2012
    Auckland, New Zealand
    Chris
    and.....here we go...
     
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  6. Jonathan F/2

    Jonathan F/2 Mu-43 Hall of Famer

    Aug 10, 2011
    Los Angeles, CA
    I don't know if light hitting an M43 sensor is the same as light hitting an FF/FX mirrored camera. I've noticed using similar settings in daylight, that my M43 cameras are more prone to hit the maximum 1/4000th shutter speed as opposed to my FF/FX camera bodies which seem to stay below 1/4000th despite shooting with a fast aperture speed.
     
  7. Amin Sabet

    Amin Sabet Administrator

    Apr 10, 2009
    Boston, MA (USA)
    Probably the base ISO of your MFT cameras is higher.

    Sent from my Galaxy Nexus using Mu-43 App
     
  8. Kilauea

    Kilauea Mu-43 Regular

    110
    Jun 9, 2012
    Canada
    Nicolas
    Thanks for the answer.
     
  9. Amin Sabet

    Amin Sabet Administrator

    Apr 10, 2009
    Boston, MA (USA)
    As you can see, this discussion doesn't usually get get heated around these parts :).

    Sent from my Galaxy Nexus using Mu-43 App
     
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