Vixen SD81SII Super ED Refractor Telescope

Vixen's standard "photo-visual" SD apochromatic refractor with a handy focal length of 625mm.  Vixen SD apochromatic refractors feature "Super extra-low Dispersion" optical glass in its objective lens. The SD81SII has a ring spacer around the objective lens to make the diffraction pattern of stars visible equally for more refined star images in astrophotography. With the use of an SD reducer HD kit or SD Flattener HD kit, the image circle of 44 mm in diameter is obtained to be used for photography with DSLR cameras with full-frame imaging sensors. A ring spacer placed around the objective lens refines star images beautifully in astrophotography. In the previous SD81S model, a set of three tiny tin foils are placed around the objective lens as a spacer between the doublet lens. The end of the tin foils protruding over the objective lens obstruct the incoming light. As a result, the protruding tin foils make the light of diffraction of stars chipped radially. Exchanging the tin foils f