What is an Extension Tube?
Extension tubes are placed in the end of a drawtube to extend the length of the drawtube. If you have replaced a high-profile focuser with a low-profile model, an extension tube may be necessary to reach focus. A longer drawtube is another option to consider. Extension tubes can also be useful for alternating between visual and photographic positions.JMI sells standard and enhanced extension tubes. The enhanced version includes a compression ring for holding equipment without scratching the surface. The adjusting screw presses against the ring which tightens around the eyepiece or accessory. Filter threads are also included in the bottom of the extension tube for holding 48mm filters.
