My amateur telescope making page

The "Deep Space Scope" Design

Home | Astronomy | DS-3 | Secondary cage construction Secondary cage Seconary cage, inverted
Two views of the secondary cage, or ring. Inset picture, below - close-up of the secondary "cell".

Next, we need to create the secondary cage. Depending on how you look at it, weight in the secondary cage will either make your bearings larger, or force you into adding counter weight. See Bearings construction and mounting below for details on balancing the telescope. There is also some debate as to how far the eyepiece should be away from the secondary - should you bring it as close as possible, minimizing the size of the secondary, or should you use the focuser as part of your baffling system. I choose to get the focuser as close to the secondary as possible, but choose a focuser that will keep my eyepieces semi-baffled. Using NEWT, and taking vinyetting into account, I chose an uncluttered secondary ring diameter of 13". Add 1/4" for "stuff" that we will have invading the light path, and the secondary ring needs to be 13 1/2" in diameter. Closeup of spider