52mm Drawtube Cap for Darks on Newtonians

thingiverse

Newtonians... If you've got one, chances are you've noticed that taking Dark Calibration Subs at night isn't possible because those large tubes leak a bit of light. I designed this cap to be placed on the drawtube from the inside. It's a no-brainer that the main telescope cap/cover should also be used to make the internal area even darker. I ran some tests with an ASI1600MM at 1 pm during a sunny day: 1) With gain set to zero, darks looked great up to 300 seconds. 2) The same result was achieved with unity gain. 3) I'm not sure about gain 200...it seems like some light is still leaking in somehow... 4) Not yet tested at night time, but it should work okay... Let me know how it performs if you decide to test it. The cap fits a 52mm drawtube tube - my specific case being the Skwatcher 130PDS standard Crayford focuser. (P.S. I printed with 88% infill using Black PETG)