| Close-up
and Macro Photography
by Chuon-Szen Ong
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EXTENSION
TUBES Extension
tubes are another set of attachments that are often used in
achieving larger than the normal lens magnification for macro
photography. The extension tubes are mounted between the lens
and the camera body.
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Nikon
PK-13 and PK-11A extension tubes
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These extend the distance between the lens and the film plane on
the camera, increasing the magnification of the subject on that
film plane. It is a similar concept to moving a slide projector
further away from the white screen to increase the size of the
projection. However, in the case of the camera and lens extension
the film size is of a fixed dimension, so the further away the
lens is from the film plane, it is effectively cropping more
off the borders of the original image projection through the
lens. These extension tubes should not be confused with tele-converters.
The extension tubes are simply hollow tubes at specific lengths
to allow precise steps in lens to camera extension, while the
tele-converters have a magnifying lens element in them that
increases the focal length of the lenses by the specified multiplier
(1.4x, 2x, 3x, etc…).
| The current Nikon series of extension tubes consist of a set of
three: an 8mm PK-11a, a 12.5mm PK-12 and a 27.5mm PK-13* extension tube, plus the PN-11* extension tube. As with the lens reversal adaptor,
the PK-11 extension tube is meant for manual bodies while
the PK-11a extension tube must be used for all AF bodies
with electrical/electronic contacts in the lens mounts.
*Note: The PK-13 is the standard extension tube
for the manual focus 55mm AI-S Micro-Nikkor and the PN-11
is the standard extension tube for the manual focus 105mm
AI-S Micro-Nikkor to achieve their full 1:1 life-size
capability. On their own, the 55mm and 105mm Micro-Nikkors
will only reach a maximum of 1:2, half life-size magnification. |
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| MF
55mm f/2.8 AI-S Micro-Nikkor set
at 1:10 (second scale line from top) |
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MF
55mm f/2.8 AI-S Micro-Nikkor with PK-13 set at 1:2 (top
scale line) |
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| MF
55mm f/2.8 AI-S Micro-Nikkor set
at 1:4 magnification |
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MF
55mm f/2.8 AI-S Micro-Nikkor with PK-13 set at 1:1.5 magnification |
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