iPhone 5 focal length math

Discussion in 'Digital Photography' started by DirtySocks85, Dec 2, 2012.

  1. macrumors demi-god

    DirtySocks85

    Joined:
    Mar 12, 2009
    Location:
    Wichita, KS
    #1
    So I'm fairly new to photography, and I expect that my math could be a bit off, but I was trying to figure out the focal length (per sensor size) on the iPhone 5 and this is what I came up with.

    So the listed focal length in the EXIF data on my iPhone photos is 4.13mm.

    I believe I read somewhere that the crop factor of the iPhone sensor on the 4S and the 5 is 7.5 (if this info is wrong it throw off everything else).

    So if I'm understanding how the focal length math works, this is essentially the same angle as about 30mm on a full frame sensor or 50mm on a 1.6 crop factor sensor (such as most entry level DSLRs).

    Would this be correct? This is mostly just a thought exercise, but would be good information to keep in mind while shooting with my iPhone.
     
  2. mulo, Dec 2, 2012
    Last edited: Dec 3, 2012

    macrumors 68020

    mulo

    Joined:
    Aug 22, 2010
    Location:
    Behind you
    #2
    the iPhone 5 has a 4.1mm focal length lens with a crop factor of 8.05 totalling a FF field of view of around 33mm, or a 1.6x crop field of view of 20mm
     
  3. thread starter macrumors demi-god

    DirtySocks85

    Joined:
    Mar 12, 2009
    Location:
    Wichita, KS
    #3
    Ah, thanks for clearing that up Mulo!
     
  4. macrumors 68000

    Joined:
    May 14, 2002
    Location:
    Where am I???
    #4
    Focal length is a property of a lens, and is unaffected by the sensor size. I say this not to be pedantic, but because it's important not to get these types of things confused. Focal length does not change with sensor size. Ever.

    So:

    The iPhone's camera lens has a focal length of 4.1mm. The field of view of that lens is equivalent to that of a 33mm lens on a full frame camera.

    If you don't shoot with a FF camera, then I'm not sure of what value this information is.
     
  5. thread starter macrumors demi-god

    DirtySocks85

    Joined:
    Mar 12, 2009
    Location:
    Wichita, KS
    #5
    Right, that's what I was getting at. I was just trying to get a comparison for field of view. Mostly out of curiosity. Thanks.
     

Share This Page