Focus & Macros

Macro photography is interesting and fun. However, it places a premium on both equipment and technique. First, let’s distinguish between macros and closeups.

  • The difference between macros and closeups is one of definition and depends primarily on
    • Your lens and
    • Any additional lens attachments, and
    • Not your camera (D-SLR assumed).
  • Suppose your camera’s sensor is exactly the size of a postage stamp, then
  • A life size photo of the stamp (abbreviated 1:1) would fill the frame exactly
    • This is a macro (1:1 or larger)
  • If the stamp doesn’t fill the frame entirely then it’s a closeup
    • If it fills 1/2 of the frame, for example, it’s known as a one-half life size image (1:2)
    • Most lenses are 1:3, 1:4, ….
  • Not everyone uses the same definition.
  • Much of what’s labeled macro is actually a closeup

Equipment – There are a number of options for doing macro photography.

  • Use a macro lens (note some lenses sold as macro are 1:2)
    • Highest image quality option (greatest cost)
    • Also useful as a quality prime lens (mine is 105mm)
  • Use lens accessories with a regular lens (not all accessories work with all lenses)
    • General caution – anything placed on your lens will have some adverse effect on image quality. The better the accessory, the less the effect.
    • Teleconverter (TC) – attaches to camera  & lens attaches to TC
      • Comes in several strengths (1.4X, 1.7X, 2X)
      • These are lens focal length multipliers, e.g.
        • 2X will make your 200mm lens a 400mm
        • 2X makes f/5.6 become f/11 (loss of light means capture takes longer)
        • 2X makes 1:2 macro become 1:1
        • Points 1 & 3 above are good; #2, not so
        • Excellent all around (telephoto and closeup option)
        • The greater the multiplication factor, the greater the adverse effects (I use a pro grade 1.4X – primarily to make my 300mm lens a 420mm equivalent)
    • Closeup lens – screws into lens like a filter
      • Comes in strengths
      • Unlike TC, this is good only for closeups & macros
        • If it’s on your camera you can’t focus to infinity
        • It will only focus in a narrow distance range (often a range of 1-3 feet)
      • For its intended use, the optics are better than using a TC
      • Coupled with a zoom lens, makes a versatile closeup/macro option but, alone, probably not 1:1
    • Extension tubes and bellows are used primarily for macro photography
      • A bellows is, in effect, a variable length extension tube
    • Reversing Rings are an inexpensive option (with the right lens)
      • Article #1 (overview + good sample images)
      • Article #2 (detailed technical explanation)
      • The wider the wide angle lens the greater the magnification,
        • e.g., a reversed 20mm lens has greater magnification when reversed than does a 28 mm lens and so on.
          • Connecting two lenses is referred to as stacked lenses.
            • This is not a good option as there is a lot of weight when the two lenses are joined, and a lot of elements.

    Equipment magnification examples-
    #1 – Nikkor 105mm 1:1 lens; #2 – 105mm lens + Closeup Lens
    #3 -105mm lens + 1.4X TC; #4 -105mm lens + Closeup Lens + 1.4X TC
    Sensor size (Nikon D300) is 23.6 x 15.8mm; penny diameter is about 19mm. #1 is 1:1 and #4 is about 2:1

    Technique – Technique begins with “T” and that stands for Tripod. When you’re dealing with paper thin depth of field, there’s no way you can hand hold and achieve focus where it’s needed. The next two examples tell it all. Click to enlarge.
    Left – focused on dollar bill; Right – focused on penny. 105mm 1:1 macro lens, plus 1.4X TC, plus Canon 500D close up lens for about 2X life size. f/4.8

    Of course we could use a smaller aperture to increase the DOF – although that’s not always practical or what we want (if we want selective focus). Here’s what happens if we use a smaller aperture than the f/4.8 used above.
    L – f/14; R – f/29. Even at f/29 the problem of the out of focus $1 isn’t solved (and diffraction may be working against us as well).

    Virtually every element of macro technique has to do with coping with shallow DOF and its effect on focus. Besides a tripod, considerations include-

    • Cable release (or timer) to eliminate camera movement
      • Mirror up to reduce vibration due to mirror slap
    • Precise camera positioning and alignment
      • Sensor plane must be exactly parallel to the plane of the subject (mine wasn’t on the above penny images; compare “LIBERTY” & “2008” on image 2-4 in the 1st  set)
      • Consider a focusing rail for precise camera positioning
    • Use manual focus (and of course, Aperture Priority or manual exposure)
      • Auto focus cannot reliably focus exactly where you want/need
    • Focus method
      • Use Live View if available
        • 100% view (many viewfinders only show 90-95% of the frame)
        • Eliminates focusing errors due to possible optical misalignments in the camera’s mirror and viewfinder screen (they aren’t used in LV)
    • Subject movement
      • Critters – they can be difficult
      • Plants in the wind – use a “Plamp

    NOTE – a good macro setup can eliminate the need to scan certain documents; just take a picture. Macro lenses often provide better optical performance all the way to the frame edges and corners – where the performance of other lenses often degrades due to straight lines becoming curved and showing color aberrations. This high quality throughout the frame is important for document copying.

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