For 1.5 frame, is 50mm better than 85 for portraits?

Discussion in 'Digital Photography' started by DeanB, Mar 18, 2007.

  1. DeanB

    DeanB Guest

    What's the prefered FL for head/shoulder portraits on a 1.5 frame
    camera, such as Nikon? I feel that on FF the 85 provides for the best
    facial impression (or even a 100 for that matter) but I have not
    experimented much on the new system.
     
    DeanB, Mar 18, 2007
    #1
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  2. DeanB

    Lionel Guest

    I personally prefer 50mm, but it also depends on the subject, & on how
    much working room you have. 85mm is nice too, but you'll need to be
    some way from your subject. ;^)
    If possible, borrow or hire a few sizes & give them a try.
     
    Lionel, Mar 18, 2007
    #2
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  3. : What's the prefered FL for head/shoulder portraits on a 1.5 frame
    : camera, such as Nikon? I feel that on FF the 85 provides for the best
    : facial impression (or even a 100 for that matter) but I have not
    : experimented much on the new system.

    Actually if you are wanting to get the same function as a 50mm lens on a
    35mm film camera you would want a 32mm lens. True, if you don't mind
    standing much further away a longer lens can be used to get the same
    framing of the subject. But if you are trying to get the same framing from
    the same distance from the subject you need a 32mm lens. The main
    difference would be a difference in Depth of Field. But that can be
    corrected with a change of Aperture (and a change of shutter speed to
    match).

    Randy

    ==========
    Randy Berbaum
    Champaign, IL
     
    Randy Berbaum, Mar 18, 2007
    #3
  4. DeanB

    DeanB Guest

    What about the distortion by such a short focal length? Agreed the
    50mm will get you the same crop as an 85 at full frame, but I dunno
    about the actual facial distortion of using such a smaller FL.
     
    DeanB, Mar 18, 2007
    #4
  5. : What about the distortion by such a short focal length? Agreed the
    : 50mm will get you the same crop as an 85 at full frame, but I dunno
    : about the actual facial distortion of using such a smaller FL.

    Distortion (of the type you are reffering to) happens when the field of
    view varies one way or the other from the "normal" lens. This normal Focal
    Length (FL) for a 35mm film camera is aproximately 50mm, with a horizontal
    Field of View (FOV) of about 40 deg. If the image taken with a different
    sized sensor and an apropriate FL lens gives an image that has that exact
    same 40 deg FOV there should be no difference in distortion purely
    attributable to the wider FL. It is true that it is more difficult to
    accurately manufacture a wider lens and so slight manufacturing error
    distortion could appear. But manufacturing is becoming more accurate all
    the time and so such abberations on all but the most extreme FLs should be
    nearly indistinguishable from an older 50mm film lens. Even with an
    extreme fisheye lens, if you cut out a piece from the very center of the
    lens that represented the "normal" image the distortion would be much
    less than you would expect.

    IMHO

    Randy

    ==========
    Randy Berbaum
    Champaign, IL
     
    Randy Berbaum, Mar 18, 2007
    #5
  6. DeanB

    ASAAR Guest

    If you prefer those focal lengths, divide them by 1.5 to get the
    equivalent lens focal lengths when used with Nikon's DSLR bodies.
    I've read that the "multiplier" is actually closer to 1.52, but such
    a small difference is insignificant. This would require focal
    lengths of about 56mm and 66mm to provide the equivalent FOVs and
    focal lengths of the 85mm and 100mm lenses used with film or Nikon's
    as yet hypothetical FF camera. The inexpensive 50mm f/1.8 Nikkor or
    the somewhat more expensive f/1.4 version would make good portrait
    lenses, and you might want their wider apertures to reduce DOF if
    all that you have is the common 18-55mm kit lens. Nikon's 18-70mm
    is a better lens and covers both of the FOVs that you prefer.
     
    ASAAR, Mar 18, 2007
    #6
  7. DeanB

    DeanB Guest

    Randy - I don't mean chromatic aberation. What I am getting at is the
    subject's nose appearing larger and closer to the lens as you reduce
    the focal length. In 35mm world the perfect FL is 85-100 mm, and there
    are opinions on which of those is best too. Go too far back with a
    telephoto and the subject appears too flat.
     
    DeanB, Mar 18, 2007
    #7
  8. Well, if you like 85 FF, 85 / 1.5 = 56.666667 will give the equivalent
    field of view on a 1.5x camera. I do in fact find my 58mm lens very
    nice for portraits.
     
    David Dyer-Bennet, Mar 18, 2007
    #8
  9. DeanB

    JR Guest

    Use the longest lens you can...if you want the look of the 85mm, then
    use the 85mm...film or digital...A 50mm lens on a digital gives the
    equivalent of 75mm on a film camera, but its as if the 50mm was used
    then cropped and enlarged...so all the characteristics of the 50mm lens
    still apply. So yes you will get the same facial distortions. I hope I
    am explaining it correctly. Now if you dont have the room to step back
    a few feet then you will need a shorter lens.

    JR
     
    JR, Mar 18, 2007
    #9
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