AstroBKK
Home made light and dew shield for C11 with Starizona Hyperstar
My urban observation spot being heavily polluted the use of a light shield is necessary to prevent public lighting strays from entering the scope. The use of a Hyperstar makes things a bit more complex, especially if one wants to keep it on the scope to avoid unpractical mounting/un-mounting and the risk of losing the collimation.
A DIY light/dew shield design with the following features was built with following features:
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Sufficient length to encompass the HS and camera assembly.
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Camera cable management.
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The shield must be firmly secured to the OTA to avoid creating tensions in the camera's cables or even catastrophic damage in case of a chute on the HS assembly (especially when moving the mounted scope on uneven ground with Wheeley Bars).
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The shield should be rigid enough to allow the fastening of a dust-proof protective cap.
The shield is made from a 3mm sheet of black HDPE ordered from RS Pro (Stock No.:408-3807), delivered in 1000mm x 500mm size, which perfectly fit the C11, no resizing is needed. One side is glossy, and the other is matt. However, dull light reflections can still be observed on matt side, the interior is thus padded with a black rubber foam sheet (RS Pro stock No.:733-6753).
The various notches are cut as shown in scheme A, using a cutter repeatedly on a same track to get a clean cut.
1/ The OTA-shield fastening notches are cut to fit the two Celestron 11" CGE Dovetail bars (#94219) installed on the top and bottom of the OTA. The central part of each notch is kept uncut as it secures the firm assembly of the shield to the OTA with a knob on the CGE bar (see scheme B).
2/ The V shape notches form a hole when the sheet is folded to a tube shape. They are placed at a height so that the cable hole faces the bottom of the camera. It is thus dependent on the specific height of the setup used. Value shown here (325mm) is for ASI294 + Adaptor + filter drawer + Hyperstar v4.
3/ The positions of the four assembly holes depend on metal mending plates to be used. The length of these plates is important, too long or too short a space between the screws (blue arrow in scheme C) would create deformation that will result in a non-circular section after folding. For the 3mm thick HDPE sheet used, a 3cm space gave a perfect result. The bolt is chosen (or cut) so that nothing protrudes in the tube beyond the washer & the nut.
4/ Black cloth tape is applied on the junction.
5/ Cap, to be updated later.
