Sky-Watcher has a passion to produce some of the finest optics to capture the
night sky. In 2010, Sky-Watcher sent ripples through the astronomical community
by unleashing a rumor of a 150mm Apochromatic refractor. Fast-forward to the end
of 2011, and the rumor is reality.
The Esprit 150mm is the largest Apochromatic refractor made by Sky-Watcher.
This formidable instrument produces razor-sharp, false color-free views, highly
suitable for astrophotography and visual observing. Our comparison with a high
priced competitors scope was a draw.
The objective lens assembly is crafted from two pieces of Schott optical
glass, and one piece of Ohara FPL-53 low-dispersion glass. This combination
produces high resolution images with no detectable false color.
The rear field flattener yields a sharp 44mm diameter photographic field with
minimal impact to focal length and focal ratio.
No fewer than 6 knife-edge baffles have been added to ensure contrast-robbing
stray light is eliminated.
Sky-Watcher's new 3.5" dual-speed linear power roller bearing focuser is
tough enough to drive heavy accessories with virtually no slippage. Unlike
traditional Crayford focusers which surround the drawtube with roller bearings,
the linear power focuser places the bearings along a single metal track mounted
along the drawtube, so the drawtube is never flexed or placed under
compression.
The locking mechanism of the linear power focuser improves on the Crayford
design, by retaining the desired focus, with no flexure or bending of the
drawtube. An engraved linear scale helps set the focus close to where you need
it.
The focus knobs can be rotated to change their orientation to suit the user.
A built-in camera angle adjuster means easy and precise rotation of the camera
and star diagonal independent of the focus knobs.
Apochromatic refractors have somewhat of a cult following; they are
considered the finest instrument to observe and photograph the skies. Once
relegated to a price range affordable by those drowning in money, they now swim
in the shallow end
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