Designed wtih the discerning astrophotographer in mind, Sky-Watcher USA’s top-of-the-line Esprit refractors deliver the kind of imaging performance one would expect from telescopes costing thousands of dollars more. With their three-element air spaced objective lens design, false color is completely eliminated, yielding exceptional contrast and sharpness. The included 2-element field corrector guarantees a flat field across the entire imaging plane. The Sky-Watcher Helinear Track focusing system provides a smooth, rock-solid focuser with zero image shift. All Sky-Watcher USA Esprit refractors come with a 9 x 50 right angle finderscope, 2-inch Star diagonal, 2-element field flattener, camera adapter, D-style dovetail and padded case. Everything you need to get out under the stars. 100 mm apochromatic 3-element refractor 550 mm (f/5.5) Fully multi-coated Thread-on field flattener 2.7" focuser w/micro focus Back Focus - 69.8mm Image Circle - 40mm Lens Glass - FPL-53 ED and Schott Glass Focuser Travel - 112mm D-Style Dovetail 2" Diagonal with dielectric coatings 9x50 RA erect-image finderscope Canon camera adapter Tube rings with CGE style dovetail bar Aluminum foam lined case Weight 16.3 lbs. Length 24.5/18.3 inches 100mm Apochromatic 3-element refractor. 550mm (f/5.5) focal length. Thread-on field flattener. 2.7" focuser w/micro focus. 2" diagonal with dielectric coatings.