Celestron Off Axis Guider OAG for Astronomy imaging Dobsonian The CEM40 also uses iOptron's

The CEM40 also uses iOptron's ultra-quiet

Lifetime transferable warranty

All internal surfaces threaded and blackened for no reflections

and there is no risk of cleaning solution migrating from the top of the lens and seeping around edges to be trapped in between elements

5mm Field Stop Diameter 34

Celestron Off Axis Guider OAG for Astronomy imaging Dobsonian The CEM40 also uses iOptron'sOVERVIEW Most accurate way to guide improved accuracy compared to using a separate guide scope. 12. 5mm multi coated prism with aluminised backing for maximum reflectivity and illumination to the autoguider Fixed orientation helical focuser for easy, smooth and accurate autoguider focus 48mm clear aperture supports full frame cameras without vignetting Includes adapters with the correct spacing for DSLR cameras, Nightscape CCD and other popular