JINGERL 20mm/25mm/35mm/40mm/70mm Astronomical Telescope Reflecting Mirror - 30mm Diagonal Mirror for Stargazing & Astrophotography Accessories (Perfect for Backyard Astronomy & Night Sky Observation)

Astronomical Telescope Auxiliary Mirror 20/25/35/40/70mmReflecting Telescope Mirror Inclined Mirror MirrorCaliber:35mmFocal Length: -----Astronomical Telescope Auxiliary Mirror 20/25/35/40/70mm Reflecting Telescope Mirror Inclined Mirror MirrorElliptical plane mirror short axis D=35mmCaliber D (short axis) 35mmFocal length F------Edge thickness H 6.8mmThe Surface Precision Λ 1/3Coating Aluminum plating plus protective filRemarksUsed as optical axis steering for Newtonian astronomical telescopeShort axis: refers to the length of the short side diameter20mm short-axis secondary mirror, with a short side length of 20mm, aluminized film and protective film on the surface, suitable for use with 76mm-diameter reflective primary mirror.25mm short-axis secondary mirror, with a short side length of 25mm, aluminized film and protective film on the surface, suitable for use with 114mm-diameter reflective primary mirror.35mm short-axis secondary mirror, with a short side length of 35mm, aluminized film and protective film on the surface, suitable for use with 127mm, 133mm, 135mm, 150mm, aperture mirror primary mirrors.40mm short-axis secondary mirror, short side length 40mm, surface aluminum coating and protective film, suitable for use with 127mm, 133mm, 135mm, 150mm, aperture mirror primary mirror.70mm short-axis secondary mirror with a short side length of 70mm. The surface is coated with aluminum and protective film. It is suitable for use with a 203mm-diameter reflective primary mirror.