Macrophotography

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Macrophotography

• FDCC - May 2008

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macrophotography

• Strict definition - From life size to limit of
  unaided visibility
• Loose definition - about 1/3 life size to limit
  of unaided visibility

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Magnification

• Magnification is usually represented as a ratio
• Life size 11
• Half life size 12
• Twice life size 21
• A lens magnification is based on a full-frame
  sensor/film camera
• On a crop camera, the effective ratio is
  magnified
• Canon 1.6 crop 1.61 ratio
• Nikon 1.5 crop 1.51 ratio

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Curvilinear Distortion

• The outer surface of all distal lens elements are
  curved
• This curvature results in slightly different
  focal distances to the sensor plane
• For objects feet or more away, this has very
  little impact on focus
• However, for macrophotography it can have a
  dramatic impact on focusing
• Focus on center, periphery is out of focus
• Focus on periphery, center is out of focus
• Dedicated macro lenses are corrected for this
  phenomenon

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Tools of Macrophotography

• Conventional lenses with macro capabilities
  (i.e., close focusing)
• Dedicated macro lenses
• Extension tubes
• Bellows
• Macro ring flash
• Macro rail

Kenko extension tube set
Nikon Micro 105mm f/2.8 VR
Sigma 150mm f/2.8 Macro
Nikon bellows
Canon MP-E 65mm f/2.8 1x to 5x magnification
Nikon E-TTL ring flash
Velbon Macro Rail
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Conventional Lenses

• Many conventional lenses have macro capabilities
  that provide up to 12 (half life size)
  magnification
• Generally, they tend to suffer optical
  distortions at macro settings
• However, they are typically inexpensive

Sigma 17-70 f/2.8-4.5 Macro
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Dedicated macro lenses

• Usually provide 11 magnification to infinity
  focus
• Have high-quality lens elements specifically
  designed for high magnification
• Tend to be extremely sharp
• Many portrait photographers use macro lenses
• Fixed focal length
• Substantially more expensive

Pentax 100mm f/2.8 Macro with hood
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Extension tubes

• Fit between camera body and lens
• Have no optics
• Increase the distance of the lens to the sensor,
  thus increase magnification
• Lose infinity focus
• More expensive ones maintain electrical
  communication between camera and lens
• Maintains autoexposure, focus and TTL flash

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Bellows

• Similar to extension tubes, but variable
  extension
• Do not maintain electrical communication between
  camera and lens
• Lose autofocus, autoexposure and TTL
• Generally not used today

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Macro Ring Flash

• Magnification reduces the amount of light that
  strikes the sensor, thus flashes are often needed
• Shoe-mounted or pop-up flashes cannot illuminate
  a macro subject because the lens impedes the
  light path
• Macro ring flashes mount on the end of the lens
  to provide flash illumination
• Some provide E-TTL, while others do not

Sigma EM-140 Ring Flash
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Macro Ring Flash

• Conventional flashes can be used with brackets
  and diffusers
• Need off-camera cable to preserve E-TTL

Delta Flip Flash Bracket II
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Aperture Diffraction

• Aperture diffraction occurs when the aperture is
  very small
• The result is softness of the image
• This phenomenon is magnified with macro
  photography
• Thus, the optimal aperture for most dedicated
  macro lenses is around f/11
• Larger apertures have thin focal plane, thus have
  narrow depth of field
• Smaller apertures have diffraction, thus the
  image is soft

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Purchasing Macro Lenses

• Optically, all dedicated macro lenses will be
  about the same
• The differences in prices include
• Brand name
• Fast autofocusing (ultrasonic motors)
• Internal focusing (lens does not change length)
• Included accessories
• Lens hood
• Case
• Tripod collar

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Macro Technique

• Moving object
• Monopod or free-hand
• Rails often of little use
• Manual focus
• Focus on a point, then move towards that point
• Repeat

• Stationary object
• Tripod
• Mirror lock-up
• Manual focus
• Rails help significantly

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Focus stacking

• A lack of depth of field is the principal problem
  with macro photography
• Focus stacking is the process of taking several
  shots at different focal planes, then using the
  in-focus regions of those images to make a single
  image thats in focus throughout
• Avoid changing the lens focus as this also
  changes the magnification
• Helicon Focus is a software package that provides
  this technique
• Focus rails are excellent for stacking