Increase for 3 inch focus base, 1.25 inch extra length | Starlight

If you want to place a camera behind your telescope and you can't get the focus far enough out, an extension for your focus ring of 3 inches will help. This moves the focus ring 1.25 inches, or about 3 cm, further from the base.

This extension tube from Starlight Instruments has a diameter of 3 inches and sits between the base and the focus lens. If you use the flat 3 inch focus base For DIY projects, this is the same size extension. You can find more spare parts at our telescope parts.

First, measure how much extra length you really need. Too much elevation costs you range to the inside, and then with a diagonal or certain eyepieces you sometimes can't get any focus at all. After the conversion, check that everything is still straight. How to use a Newtonian telescope, you can read in our explanation about collimating.