Sky-Watcher Esprit 100mm f/5.5 ED apochromatic triplet refractor with field flattener

The substantial Sky-Watcher Esprit 100mm apochromatic triplet uses a lens of extra-low dispersion (ED) glass, flanked by two carefully chosen mating lenses of premium optical glass. The trio delivers crisp, high-fidelity wide-field images of celestial objects. The views are unmarred by the faint but annoying halo of unfocused violet light (chromatic aberration) often seen around bright stars and solar system objects in other large aperture fast focal ratio doublet and triplet refractors. A separate thread-on Schott glass doublet field flattener provides pin-point star images across the entire 40mm image circle for superb astrophotography.

The 100mm Sky-Watcher Esprit triplet utilizes the most modern optical glasses and fabricating techniques to deliver the ultimate in small aperture high-fidelity astronomical observing and imaging. Each lens element is individually inspected for purity and absence of striations and other image-degrading imperfections. Each element is then pitch polished to exacting standards of optical fabrication and performance by highly skilled opticians and tested on an optical laser bench to rigidly controlled optical standards. The result is a high-quality, diffraction-limited optical system performing to the theoretical limits of its aperture - one that will give you years of imaging and visual observing satisfaction.

Features of this Sky-Watcher refractor . . .

Apochromatic ED triplet refractor optics: 100mm (3.94") aperture, 550mm focal length, f/5.5 focal ratio. The triplet objective lens uses mating elements of premium optical glass. The center ED element is precision-polished from high grade ED (Extra-low Dispersion) glass.

Fully multicoated optics: Each air-to-glass surface in the Sky-Watcher Esprit 100mm triplet objective lens has high transmission antireflection multicoatings on all air-to-glass surfaces for high light transmission, minimal light scatter, and excellent contrast.

Retractable dew shield: The aluminum dew shield retracts to allow the scope to fit into its hard carrying case, and extends when the scope is in use. The dew shield slows the formation of dew on the lens in cold weather to extend your undisturbed observing time. It also improves the contrast, similar to the effect of the lens shade on a camera lens, when observing during the day or when there is excessive ambient light at night, such as a neighbor's backyard security light. The telescope measures 18.3" long with the dew shield retracted and 24.5" long when it is fully extended.

Thread-on doublet field flattener: When you are ready for imaging, the Esprit 100mm includes a doublet field flattening lens that can be threaded onto the optical tube to transform your scope into an exceptional wide-field imaging Instrument. Using optical grade glass and multicoatings on all air-to-glass lens surfaces, the field flattener provides sharp, in-focus stars across a large fully-illuminated 40mm image circle. This is ideal for DSLR cameras (APS-C sensors and even those with 35mm equivalent sensors, although there will be some vignetting at the corners of a full-sized sensor) and for virtually all CCD cameras. Back focus is 69.8mm. A Canon EOS camera adapter (the most popular DSLR camera brand for astronomical imaging) is standard equipment. Optional Celestron M48 camera adapters are available for Nikon and Sony/Minolta Maxxum cameras.

Dual speed 2.7" rack and pinion focuser: The precision-made and mechanically ultra-smooth, backlash-free, rack and pinion focuser has a giant 2.7" diameter drawtube with a 2" accessory adapter. This rotatable focuser offers dual-speed focusing and has an engraved focusing scale. There are two coarse focusing knobs. The right knob has a smaller concentric knob with 10:1 reduction gear microfine focusing over the full 112mm focuser travel. This provides exceptionally precise image control during high magnification visual observing and critical DSLR or CCD imaging. The large focus knobs have ribbed gripping surfaces so they are easy to operate, even while wearing gloves or mittens in cold weather. A lock knob lets you adjust the tension on the drawtube to accommodate varying eyepiece/photo accessory loads, as well as firmly lock in a photographic focus.

2" dielectric star diagonal: The supplied standard equipment 2" mirror star diagonal of the Esprit 100mm slips into the focuser drawtube's 2" eyepiece/accessory holder. The 2" compression ring diagonal has 99% reflectivity dielectric mirror coatings for high light transmission. A 1.25" compression ring accessory adapter is standard.

Finderscope: The Sky-Watcher Esprit 100mm comes with a 9 x 50mm right-angle correct-image finderscope that is fully multicoated to insure maximum brightness and contrast. The finder shows the star field in its correct upright and right-reading orientation, as it appears to the naked eye and on star charts.

Mounting rings and dovetail: The Sky-Watcher Esprit 100mm apo has dual hinged split-ring tube rings to fit the 5.75" diameter aluminum optical tube. They are bolted to a Losmandy-style "D-plate" dovetail that fits directly into the dovetail slot on the head of many of the most popular medium to heavy capacity German equatorial mounts, such as the Celestron CGEM DX and CGE Pro and the Losmandy G11.

Shipping/storage case: The scope comes in foam-fitted aluminum-clad shipping/storage hard case.

Two-year warranty: The Sky-Watcher Esprit 100mm triplet apo is protected by a two-year limited warranty against flaws in materials and workmanship.