The Vixen Optics SD81S is new 81 mm apochromatic refractor with high-performance Super ED glass (= SD). The FPL53 glass reproduces an extremely clear and sharp image through an extremely high level of elimination of residual color defects. The SD glass is designed in such a way that it brings all the rays of violet, red, blue, yellow and green together very precisely on the same plane.
The special lens material reduces the chromatic aberration about all colors. In combination with the new optional SD Reducer HD Kit or SD Flattener HD, these refractors enable illumination with a 44mm image circle for full format SLR cameras.
The advantage of these SD refractors is their short length and low weight. The ED81SII, ED103S, ED115S refractors were originally developed for the visual observer or photographer with APS-C cameras. However, the new SD series has also been optimized for the use of full-frame cameras by replacing new inner panels. The large focuser enables heavy cameras to be attached without tilting.
The included folding mirror allows comfortable observation, even in unfavorable observation situations, and also offers a T2 thread for connecting a DSLR camera.