Auto extension tubes are designed to enable a lens to focus closer than its normal minimum focusing distance, making them exceptionally useful for close-up photography. Auto extension tubes have no optics and are mounted between the lens and camera body. By moving the lens further away from the film/sensor it allows the lens to focus closer than normal. The further the lens is moved away from the camera the closer the lens can focus, resulting in an increased magnification of the subject.
Nikon produces a range of auto extension tubes which can be used with Nikon Ai, Ai-s, AF, AF-D and AF-S (D-type) lenses. Nikon auto extension tubes do not have CPU contacts required to adjust the aperture electronically using the camera dials. The aperture, therefore, needs to be adjusted on the lens using the aperture ring. As G-type lenses do not have an aperture ring they cannot be used with Nikon auto extension tubes.
The use of an auto extension tube or combination of tubes with a total extension approximately half of the focal length of the lens being used will allow a reproduction ratio of 1:2. For example, a 50mm lens requires an extension of 25 mm (50mm divided by 2 = 25mm) - so either a combination of PK-11A (8 mm) and PK-12 (14mm) or a single PK-13 (27.5mm) could be used.
Nikon Auto PK Extension Tubes User Manual
|
Auto Extension Tubes
|
Lens Type
|
|
E / G-type
|
AF /
AF-D
|
MF*
|
|
PK-11a
8mm extension
|
No
|
Yes
|
Yes
|
|
PK-12
14mm extension
|
No
|
Yes
|
Yes
|
|
PK-13
27.5mm extension
|
No
|
Yes
|
Yes
|
|
PN-11
52.5mm extension
|
No
|
Yes
|
Yes
|
*Manual Focus (excluding non-AI lenses)
