Vixen SD apochromatic refractors feature "Super extra-low Dispersion" optical glass in its objective lens. With the use of a 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 sensor.
A lens of refracting telescopes has chromatic aberration which is caused by different wavelength of visible light (colors) focusing at different distances. The Vixen SD lenses, made of FPL53 super extra-low dispersion glass, allow for correcting the chromatic aberration over a wide spectrum of light. The SD lenses focus visible rays of light from the Cray(red), d-ray(yellow), e-ray(green), F-ray(blue) to g-ray(violet) at nearly the very same position. As shown in the diagrams of spherical aberration, it verifies that the chromatic aberration is highly corrected over a wide spectrum of light with the SD lenses. Especially the g-ray, which affects image contrast, is suppressed excellently. The SD81S delivers outstanding sharp images with high contrast for both visual and photographic applications. Brighter F7.7 images will satisfy the most demanding visual astronomer or astrophotographer.
The optical tubes of the SD81S, SD103S and SD115S are designed to be shorten to its length. It is convenent to carry and setting up and balancing the optical tube easier.
The provided filip mirror allows you to change light pass for comfortable observing posture. With two eyepieces of different focal length attached to the flip mirror, you can switch magnifications quickly.
The focuser drawtube has 60mm threads in diameter for attaching a variety of optional eyepieces and accessories for visual and photographic purpose.
This kit consists components for prime focus astrophotography with the SD81S, SD103S or SD115S optical tube. This reducer is made to be used in combination with an accessory such as a wide photo adapter 60DX, sold separately.
SD81S Optical Tube Assembly