Comparison of Sky-Watcher 80ED, 100ED, and 120ED binoculars: performance, portability, and uses

Introduction: Three Iconic Telescopes for the Amateur AstronomerSky-Watcher is well known for its instruments offering an excellent price-to-performance ratio, and its range of apochromatic Evostar ED telescopes is among the most popular. The 80ED, 100ED, and 120ED models share the same philosophy: low-dispersion optics designed to produce sharp, high-contrast images with minimal chromatic aberration. But how do they really compare to each other? And most importantly, which one best suits your needs: portable observation, astrophotography, or fixed installation?Optical Design: The Same Formula, Nuanced ResultsAll three models are based on an apochromatic doublet, combining a very low-dispersion FPL-53 (Ohara) glass with a crown glass element. This combination effectively corrects chromatic aberration while maintaining a reasonable cost and manageable weight. Unlike heavier and more expensive triplets, these ED doublets offer an excellent balance between performance and portability.In practice, the 80ED offers remarkable sharpness on stars and high contrast for planetary observation. The 100ED goes further in resolution and brightness, while the 120ED, with its larger aperture, reveals finer details and allows deep-sky observations, particularly of nebulae and galaxies.Focal Length, Field of View, and Optical PerformanceEvostar 80ED: 80 mm diameter, 600 mm focal length (f/7.5)Evostar 100ED: 100 mm diameter, 900 mm focal length (f/9)Evostar 120ED: 120 mm diameter, 900 mm focal length (f/7.5)The 80ED, with its f/7.5 ratio, offers a wide, bright photographic field—perfect for large objects like the Orion Nebula or the Pleiades. In contrast, the 100ED and 120ED prioritize resolution: their longer focal length makes them ideal for planets and lunar details. The 120ED, with its wider aperture (f/7.5 but larger diameter), provides brighter images at equivalent magnification.Portability and MountingWeight and tube length are essential criteria depending on whether you practice astronomy on the go or in a fixed location. Here are the typical specifications:80ED: approximately 3 kg, tube length 60 cm—ultra-portable.100ED: approximately 3.5 kg, tube length around 90 cm—still manageable but more bulky.120ED: approximately 5 kg, 1 m tube—better suited for a fixed mount or stationary use.The 80ED is undoubtedly the most practical for travel and impromptu observation sessions. It installs easily on a lightweight mount like the AZ-GTi or EQ5. Conversely, the 120ED requires a robust equatorial mount, such as a HEQ5 or EQ6-R, especially for long-exposure imaging.Visual and Astrophotography UseFor visual observation, the 120ED takes the lead in contrast and resolution power: Jupiter, Saturn, and open clusters reveal exquisitely defined details. However, the 80ED remains impressively sharp on the Moon and planets, especially if you seek simplicity and portability.In astrophotography, the differences become clearer: the 80ED, with its moderate focal length and lightweight design, is ideal for starting deep-sky photography with a portable mount. It tolerates long exposures without requiring millimeter-perfect alignment. The 100ED is an excellent compromise for imaging both extended nebulae and medium-sized galaxies. Finally, the 120ED appeals to experienced astrophotographers seeking brightness and resolution on more compact targets, provided they have a precise mount and a suitable field flattener.Recommendations Based on UsePortable or travel use: the 80ED is unbeatable. Compact, lightweight, and quick to set up, it offers surprising performance for its diameter.Home or mixed use: the 100ED is an excellent compromise between power, focus, and weight. It remains easy to handle while significantly gaining in resolution.Demanding astrophotography or fixed use: the 120ED fully unleashes its potential with a stable mount and a well-adjusted imaging setup. Its optical precision and generous diameter make it ideal for advanced users.In summary: Three consistent instruments, three views of the skyThe Sky-Watcher ED apochromatic telescopes form a cohesive family, guided by optical quality and versatility. The 80ED focuses on lightweight and simplicity, the 100ED balances versatility and performance, while the 120ED stands out as a power reference among FPL-53 doublets. Whichever you prefer, each will offer you sharp, high-contrast images free of color fringing—the pleasure of observing the night sky without compromise.Final AdviceBefore choosing, consider your observation habits above all. If you love going out to observe under a dark countryside sky, the 80ED will go everywhere with you. If you have a balcony or garden where you can set up your equipment permanently, the 100ED or 120ED will make the most of every clear night. In any case, these telescopes will remain reliable companions for many years of celestial exploration.