Factors to Consider
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from NightWatch, by Terence Dickinson

Telescope Type Will Telescope Usually Be Transported to Observing Site? Is the Main Observing Site an Urban Location or a Dark Rural Location? Will Telescope Be Used For Celestial Photography?
2.4″ to 4″ achromatic refractor generally easily transportable good performance in an urban environment, will not equal other types under dark skies not recommended except for shooting the moon
3″ to 7″ apochromatic refractor easily transported up to 5″ size; larger models are hefty a good choice if you are limited to mostly urban and some rural observing a favourite for astrophotographers
4″ to 8″ Newtonian reflector, equatorial mount easily transported, although some 8″ units are bulky good all-round performer astrophoto versions often have beefier mounts and specialized accessories
10″ or larger Newtonian reflector, equatorial mount 10″ units are about the limit for convenient transport performance limited in an urban environment; excellent performer under dark skies will yield excellent results but only with massive mount and proper accessories
4″ to 8″ Newtonian reflector, Dobsonian mount easily transported good all-round performer not recommended
10″ or larger Newtonian reflector, Dobsonian mount transportable, but van may be needed urban environment severely limits usefulness of this type, designed for use under dark skies not recommended
4″ to 8″ Schmidt-Cassegrain easily transportable in any vehicle good all-round performer excellent range of accessories for backyard photographer
3.5″ to 7″ Matsukov-Cassegrain exceptionally compact in smaller apertures often a favorite for urban astronomers, who occasionally observe from really dark sites long focal ratio limits photography to moon or ccd imaging
Telescope Type Will Telescope be Primarily Used For Observing Sun, Moon Planets and Other Bright, Easy-To-Find Objects? Will Telescope be Used For Viewing Nebulas, Star Clusters and Galaxies? Will Telescope Frequently Be Used For Daytime Land Viewing?
2.4″ to 4″ achromatic refractor excellent performance, long focal ratios and equatorial mount preferred not recommended suitable and recommended
3″ to 7″ apochromatic refractor unsurpassed for consistently fine lunar and planetary performance. The preferred choice if you can afford one excellent definition and contrast but limited by their aperture Tele-Vue “Pronto” and Astro-Physics “Traveler” especially recommended for daytime viewing
4″ to 8″ Newtonian reflector, equatorial mount generally good performance, used to be standard planetary telescope until advent of apochromatic refractors in 1980s 6- and 8-inch models especially recommended not recommended
10″ or larger Newtonian reflector, equatorial mount good results obtained in medium focal ratios with premium optics top-rated for deep-sky viewing not recommended
4″ to 8″ Newtonian reflector, Dobsonian mount generally good performance, although mounts not intended for continuous high-powered plantary viewing 6- and 8-inch models especially recommended not recommended
10″ or larger Newtonian reflector, Dobsonian mount these telescopes are not designed for viewing bright objects, and seldom produce satisfactory views compared with other types very popular as the most economical way to see the faint fuzzies. Excellent at low powers, which are used most of the time anyway not recommended
5″ to 16″ Schmidt-Cassegrain although apochromatic refractors are best in this category, the Schmidt-Cassegrain offers good planetary views deep-sky performance rivals that of any other telescope type suitable in smallest sizes
3.5″ to 7″ Maksutov-Cassegrain when well-made, this design seems to produce performance second only to the refractors in most common size(3.5 inch), these instruments are less effective than other types simply because of low light-collecting power ideal in 3.5-inch size

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