The Pentax Auto Extension Tube Set consists of three tubes (14, 28 and 56mm) that can be used singularly or in combination on the inner bayonet mount with lenses from 55mm to 500mm (excluding the 400mm lens).
Each tube provides a different degree of extension and can be used individually or together
When all three are used together, they provide maximum magnification
This three tube set offers a maximum magnification of 1.07x with the 105mm f/2.4 standard lens and automatic diaphragm operation at a preset aperture
Fully automatic diaphragm action is retained and magnifications greater than life-size can be produced