| The Celestron 90mm AstroMaster altazimuth refractor is a good choice for a beginning astronomer who also has an eye for nature. This sensibly-priced medium aperture refractor optical system is a good way to begin your journey into the night sky, as well as exploring nature during the day. It provides you with detailed high-contrast views of the Moon and planets in the heavens, as well as sharp views of birds and animals across a lake or across the way. The construction of the optical system is first rate, as the AstroMaster has all-glass optical components, with high transmission optical multicoatings for enhanced image brightness and clarity. The mount has a convenient pan handle, like the control handle on a camera tripod, for guiding the scope around the skies or the landscape. A built-in clutch makes operating the well-balanced scope with the pan handle smooth and easy. The scope assembles in only a minute or two, with no tools required. For the astronomical observer whose interests are the brighter solar system and deep space objects, the AstroMaster 90 has a lot to offer. Its 3.5” aperture has a light grasp 165 times that of the sharpest eye for nighttime and twilight use. Its sensibly large aperture and diffraction-free images make it surprisingly good for much deep space observing. Binary stars and globular star clusters are particularly well-resolved and vivid, with the contrasting colors of many binary systems showing nicely. The brighter nebulas and galaxies stand out against a darker sky background than is possible in a comparably-priced reflector with its light-scattering diagonal mirror. The AstroMaster 90 can also resolve details thirteen times smaller than you can see clearly with your unaided eye. Combine that sharpness with its two eyepieces (a 20mm for 50x magnification and a 10mm for 100x), and you have the ability to see many, many celestial and terrestrial objects that are simply invisible to the unaided eye. Its views of subtle lunar and planetary details are sharp and high in contrast, bringing the planets to vivid life in the eyepiece. Some chromatic aberration is present in the scope when viewing very bright objects at night, as it is in all achromatic refractor telescopes. However, using an optional aberration-reducing minus violet filter (#CCBF) will help eliminate the faint violet halo of spurious color for the serious lunar/planetary observer (although many people find it unobjectionable in any case). Once you have scanned your way through the solar system and the Milky Way, you can use the AstroMaster to look at things closer to home. The altazimuth mount will let you easily track objects on the ground and allow you to get a sharply-detailed closer look at nature and your surroundings. The AstroMaster 90 is an economy-priced scope that can open new worlds for you, both on the ground and in the sky.
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