Alstar 2-Inch Telescope Eyepiece Extension Tube - Bundle with - 2" Narrowband O-III Filter

Alstar 2-Inch Telescope Eyepiece Extension Tube Adapter provide extra focuser back travel sometimes needed to achieve focus with certain eyepiece or telescope combinations. More back travel is often needed for short-range terrestrial viewing or with use of a field flattener, coma corrector, or focal reducer lens. Extension tube provides extra focuser "back travel" often needed for short-range terrestrial viewing through a telescope, or for astrophotographic applications. Fits in 2" telescope focusers, and accepts 2" eyepieces or accessories. Features two locking thumbscrews to secure any inserted astronomy accessory, with a brass compression insh to prevent the marring of your telescope accessories. Machined of high quality aluminum and anodized black, durable for long time use.

• Extension tube provides extra focuser: back travel often needed for short range terrestrial viewing through a telescope; or for astrophotographic applications
• Features two locking thumbscrews to secure any inserted astronomy accessory; with a brass compression insh to prevent the marring of your telescope accessories
• Machined of high quality aluminum and anodized black; resistant for long time use
• Each Alstar 2 inch O III Filter is individually inspected and proudly inscribed with the percentage of light transmittance of the two O III emission lines
• Not only useful at light polluted sites; the contrast is also increased at dark sky sites; can be used with all 2 inch eyepieces; Filter made from high grade glass with dichroic interference and antireflection coatings