12X Zoom, 12 mm Fine Focus, Aperture

The NAVITAR 1-50486A 12X Zoom body tube contains the core zoom mechanism and determines the mechanical nature of your zoom system. Fine Focus is for applications without separate moving support systems, the Fine Focus body tubes offer focus over a 3 mm (coaxial models only) or a 12 mm (non-coaxial models) Fine Focus axial distance at the object. Available in manual and motorized versions.  The aperture function allows the user to adjust the amount of light that flows through the system without adjusting light source intensity.  The aperture also can improve depth of field when it is adjusted properly.