for visual observation, as well as short to medium exposure prime
focus, eyepiece projection, and afocal imaging astrophotography
techniques, the Vixen Optics ED80Sf 80mm f/7.5 APO ED Refractor Telescope is ideal for an amateur astronomer or photographer who is looking for a highly portable, yet capable, kit.
Vixen outfitted the ED80Sf with extra-low dispersion (ED) glass in a
fully multi-coated apochromatic lens system that corrects for both
spherical and chromatic aberrations, astigmatism, and off-axis comas.
This correction creates a wide flat field of view without distortion and
removes the blue-tinted "halo" effect for true high-contrast color
transmission. Threads on the drawtube allow direct connection of T-rings
and other camera mounts. Complementing the optical performance is a
precision Crayford-style focuser that employs a tension control system
to eliminate backlash and achieve tack-sharp views, typically not
possible with rack-and-pinion styles.
Included with the optical
tube assembly (OTA) is a flip-mirror diagonal with dual 1.25" holders.
The light path can be directed to the upper holder with the mirror in
the up position, and to the rear holder by flipping it down. For visual
observation, the mirror can hold two eyepieces to allow easy changes
from low to high magnification. When using it for imaging, the camera or
imaging system can be used in the back, and an eyepiece can be put on
top to check alignment and tracking between exposures.
To provide a
solid and secure observational platform, Vixen includes their Porta II
manual alt-azimuth mount. This version has a redesigned two-section
tripod with a higher maximum height of 67" for use with refractor-style
OTAs or for taller people who don't want to hunch. Two control knobs,
one for each axis, allows users to make small and precise adjustments
for tracking subjects. Its two 120-tooth worm gears let the altitude and
azimuth travel a full 360° circle. The Porta II operates without locks
and clutches, but rather with a friction system. This means you can
simply move the mount by hand to quickly find your subject, then use the
slow-motion knobs to track.