New design of secondary mirror cells / secondary mirror holders / secondary mirror spider

When developing the astrograph conversion kit for Skywatcher's Explorer PDS series, one of the goals was to reduce star spikes in the images.

The straight struts of the secondary mirror spider create diffraction effects at the edges. These combine to form rays in the image. With four struts, you therefore see the typical perpendicular rays around the stars.

If this detracts from the aesthetic appearance of the image, the secondary mirror must be mounted differently.

Through research by several enthusiasts, including on the cloudynights.com board, and research by Fermín Granados-Agustín and Félix Gracia Témich [https://www.researchgate.net/publication/26475864_Apodization_of_the_flat_mirror_support_of_a_newton_telescope], it was determined that it would be optimal if the individual struts were designed in curves, each forming a 180° arc in pairs.

This distributes the diffraction patterns in such a way that, while some contrast is lost (this also happens with straight struts), the patterns do not overlap into rays.

Using mathematical shapes, we design our curved spider secondary mirror mounts based on the current state of the art. These can easily be replaced with the original secondary mirror struts and telescope tube ring.

https://www.teleskop-spezialisten.de/shop/3D-Druck-Entwicklungen:::241.html