100mm F2 vs 85mm 1.8 or 1.4..which one has more "bokeh"

Discussion in 'Open Discussion' started by shaolin95, Jul 22, 2016.

  1. shaolin95

    shaolin95 TalkEmount Top Veteran

    Jul 3, 2013
    I thought I had this figured out a long time ago but checking some calculators and bokek simulators online, I got confused.
    Does 100mm F2 have a smaller DOF than 85mm 1.8 if framing the subject the same way..ie a full body shot? How about 85mm 1.4 and 135mm F2?
    I feel kind of silly now :D

  2. MAubrey

    MAubrey TalkEmount Top Veteran

    Dec 9, 2013
    Bellingham, WA (displaced Canadian)
    Real Name:
    A 100mm f/2 and 85mm f/1.8 would be about the same. A 135mm f/2 would be closer (but not quite there) to an 85mm f/1.2.

    The easiest way to compare the quantity of blur is to simply divide the FL by the f-number. 100mm f/2 = 50, 85mm f/1.8 = 47.22. For a given subject magnification, the same size physical aperture will always give you the same amount of blur.*

    *a shorter FL with a larger f-number can still give more blur if the distance between the subject and the background is small.
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