SkyWatcher Esprit 100ED Review
Whether you use a DSLR or a cooled dedicated astronomy camera, the Sky-Watcher Esprit 100ED is a high-quality, compact, and capable telescope ideal for deep-sky astrophotography and a superb instrument for visual use as well.
The Sky-Watcher Esprit 100ED is a high-quality apochromatic refractor telescope designed specifically for wide-field astrophotography. It uses three lenses in an ED triplet design to produce images with exceptional color correction. This telescope is particularly well-suited for taking pictures of large nebulae like the Veil Nebula, North America Nebula, and the Rosette Nebula, and offers a fast focal ratio with sharp images across even the largest astrophotography camera sensors, along with excellent views at the eyepiece. Premium ED refractors are versatile telescopes with minimal fuss and offer the sharpest views and images possible of any design, and the Esprit 100ED is no different.
100mm (4”) Aperture
550mm Focal Length
Triplet FPL-53 & FPL-51 optics
The Sky-Watcher Esprit 100ED is an ED triplet refractor which uses two pieces of ED glass: FPL-53 and an FPL-51 lens elements along with BK7 for the third lens element. This yields exceptionally sharp and color-corrected images much better than a normal FPL-53-only triplet or a cheaper FPL-53 doublet or FPL-51 triplet. The Esprit 100ED compares favorably to refractors from more bespoke brands such as Astro-Physics, Takahashi, and Stellarvue, at a fraction of the cost.
The Esprit 100ED comes with a matching field flattener and can easily illuminate even the largest astronomical CCD and CMOS sensors, as well as full-frame DSLR and mirrorless cameras. You can’t use the scope with a reducer-flattener for full-frame cameras due to its optical design, though if you are stuck with a smaller sensor a reducer-flattener may work (albeit pointlessly, since the unvignetted field with a reducer is going to be similar to what you can achieve with a full-frame camera at f/5.5).
At f/5.5, you get a very wide field of view with the Esprit 100ED for visual or astrophotography use and f/5.5 is considered a fairly fast photographic speed for the latter.
The Esprit 100ED features a massive 3.4” dual-speed hybrid rack-and-pinion focuser. The hybrid design refers to the additional linear rail on the opposite side of the drawtube from the racked teeth on the focuser, which rides against roller bearings to provide additional support for the focuser and avoid any play or sag in the focuser. It comes with a 2” visual back attached by default but can accept a variety of screw-on accessories. A standard Vixen/Synta-style finder bracket is attached to the left side for accepting the included 9×50 finder scope or a smaller guide scope.
For attaching to a mount, the Esprit 100ED comes with a pair of heavy-duty tube rings, mated to a thick Losmandy D-style dovetail bar which is generally what would be recommended for such a large and heavy instrument and astrophotography use. A second Vixen or Losmandy-style dovetail plate is easy to attach to the top of the rings.
The Esprit 100ED includes an aluminum hard case by default, along with a 9×50 right-angle correct-image finder scope, an M48 camera adapter, and a 2” dielectric mirror star diagonal, in addition to its field flattener. The provided finder works well, and the diagonal is high enough quality that you won’t need to replace it for visual observation.
At 16 lbs, the Esprit 100ED is beyond the capabilities of a mount like the Sky-Waatcher HEQ5 Pro or Celestron Advanced VX, especially when you factor in the additional weight of a camera and guide scope. We would recommend a mount such as the Sky-Watcher EQ6R Pro, Losmandy G11, or Celestron CGX to hold this telescope. Autoguiding is also required for a telescope of such weight and focal length.
What can you see if you look through it?
The Esprit 100ED is primarily an astrophotography telescope, but it can offer wonderful views at the eyepiece as well. The provided 2” diagonal makes installing eyepieces easy. With a wide-angle 2” eyepiece, the Esprit 100ED’s short 550mm focal length makes it ideal for viewing the largest open star clusters and nebulae, especially under dark skies; a UHC nebula filter also helps on the latter. You can begin to resolve the brightest globular star clusters into individual stars at high magnification, too, as well as see dust lanes in a handful of the brightest galaxies. High magnification and a steady night will also allow you to split double stars less than an arc second apart with the Esprit 100ED’s razor-sharp optics.
The Esprit 100ED also works well on Solar System objects, provided you can use an eyepiece with a sufficiently short focal length to enable high-magnification views. Expect to have no trouble resolving the Great Red Spot and cloud belts on Jupiter along with the disks of its four large moons, the phases of Venus and Mercury, and the ice caps and dark albedo features on Mars’ surface. You can also see thousands of identifiable details on the Moon, such as tiny craterlets, mountain ranges, and thin ridges and cracks on its surface. You can also resolve the Cassini Division in Saturn’s rings along with a handful of the ringed planet’s moons and its dull ruddy cloud bands. Uranus is a tiny turquoise dot, and Neptune may be difficult to distinguish from a star; their moons lie beyond the light gathering power of the Esprit 100ED.
The Esprit 100ED is of course quite expensive and requires a heavy-duty mount to be used for deep-sky astrophotography. At 550mm focal length, you may be unhappy with the image scale the Esprit 100ED provides for smaller targets. A telescope with a longer focal length of 1000mm or more, such as a Newtonian reflector, Schmidt-Cassegrain telescope, or Ritchey-Chrétien, is better suited for imaging small objects like galaxies.
The Sky-Watcher Esprit 100ED is a great all-around telescope for deep-sky astrophotography and visual use, offering excellent performance, though it’s a little large and expensive for beginners to handle.