3/4 depth of field

Discussion in 'Mirrorless Digital Cameras' started by pawel_baranski, Feb 5, 2012.

  1. new olympus mirrorless specs just leaked and it seems i may not go bancrupt with fuji.
    However, I'm concerned about smaller sensor - i like shallow depth on field - is olympus limiting in this case?
    new 75 1.8 is also rumored, so i wonder how this would work compared to 85 1.8 on standard crop sensor (in terms of depth of field).
     
  2. Practically, about 1 stop more than aps-c sensors or 2 stops more than film/FF.
     
  3. (Edit) Scratch that... I'll let someone else answer
     
  4. The 4/3 (and M4/3) sensor is roughly half the size of a standard 35mm negative, hence the "crop factor" of 2. Depth of field depends on the actual focal length of a lens and not on its equivalent field of view on any size of sensor or sensitive material. Thus my 25/2.8 "pancake" gives the same field of view as a 50mm lens on a 35mm full-frame film body, but its depth of field is that of a 25mm lens. Using long and fast lenses can give shallower depth of field, but it does not change the basics.
     
  5. Assuming you are cropping to US-common print larger sizes with a 4:5 aspect ratio (e.g., 8x10, 16x20, and close-enough to 11x14), then the effective "crop factor" is 1.85x, and all else being equal, a camera with a four-thirds sensor (regular or micro four-thirds) has slightly more than half a stop more depth of field than a camera with an "APS-C" sensor. (The claim that practically it's one stop overstates the difference; actually, it's 0.54 stop.) In other words, your hypothetical micro four-thirds Olympus will give you the same depth of field at about f/2.3 as a Fuji 1 or 100 (or Sony NEX or Nikon D7000, for that matter) will at f/2.8.
    So on the whole, the depth-of-field differences will be modest, and I wouldn't let them weigh too heavily in my decision. On the other hand, generally, Olympus seems to have been using sensors that are considerably behind the best sensors in noise and dynamic range (although to be fair, Canon seems to have fallen behind on dynamic range).
     
  6. Depth of field depends on the actual focal length of a lens and not on its equivalent field of view on any size of sensor or sensitive material. Thus my 25/2.8 "pancake" gives the same field of view as a 50mm lens on a 35mm full-frame film body, but its depth of field is that of a 25mm lens.​
    That is not correct. DOF depends on focal length AND aperture AND distance to subject AND COC factor (which depends on sensor size and resolution). Focal length alone is meaningless. That is why DOF calculators ask you to enter camera, focal length, aperture, and distance to subject.
    For example, the Nokton 25/0.95 is equivalent to a 35/1.4 lens on APS-C or to a 50/1.9 lens on FF (for same shooting distance and printing sizes - see lens equivalence theory). That gives pretty shallow DOF, especially since the Nokton focuses down to 17mm, so DOF will be really thin for closeup shots:
    [​IMG]
    MFT sensors allow plenty of DOF control.
     
  7. You may say that my statement is not complete: but, in so far as it compares two factors only, it is correct. Circle of confusion, being an arbitrary decision, cannot be said to depend on anything.
     
  8. Coming from a bridge camera I find the problem is less depth of field than I've been used to :)
    people do often ignore the effect of increased magnification required from the smaller 'negative' area for a given print size.
     
  9. Simple answser is, you need fast lenses and big sensor to get really narrow depth of field. m4/3 has some fast lenses, better than any other smaller sensor system. If you need more than m4/3 can deliver (ie narrower DOF), then you need a DSLR, and preferably a full frame one.
    00ZykX-439969584.jpg
     

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