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.
|
|
|
Nikon PK-13 and PK-11A extension tubes |
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.
|
.. |  |
 |
||
 |
 |
|
|
MF 55mm f/2.8 AI-S Micro-Nikkor set
at 1:10 (second scale line from top) |
MF 55mm f/2.8 AI-S Micro-Nikkor with PK-13 set at 1:2 (top scale line)
|
|
 |
 |
|
|
MF 55mm f/2.8 AI-S Micro-Nikkor set
at 1:4 magnification |
MF 55mm f/2.8 AI-S Micro-Nikkor with PK-13 set at 1:1.5 magnification
|
previous page next page
