Refracting Telescopes | Will the instrument be used primarily for lunar and planetary observing? | Will the instrument be used primarily for deep space observing? | Will the instrument be used for (1) lunar and planetary or (2) deep space photography? | Will the instrument be used for terrestrial viewing during the daytime? |
60mm (2.4") to 102mm (4") altazimuth mount refractors | Recommended, except can be difficult to find and manually track objects at high powers. | 60-70mm have limited capabilities. 80-102mm much more suitable. | (1) Lunar snapshots a possibility. (2) Not suitable. | Quite good, although field of view can be narrow. |
60mm (2.4") to 152mm (6") equatorial mount refractors | Highly recommended, but best in apertures above 70mm to 80mm. | 60-70mm have limited capabilities. 80mm and up are more suitable. | (1) Very acceptable with drive. (2) Very acceptable, if 4" and larger. | Usually unacceptable, as mount is inconvenient to use. |
Reflecting Telescopes | Will the instrument be used primarily for lunar and planetary observing? | Will the instrument be used primarily for deep space observing? | Will the instrument be used for (1) lunar and planetary or (2) deep space photography? | Will the instrument be used for terrestrial viewing during the daytime? |
4.5" to 8" equatorial mount Newtonian reflectors | Recommended, if focal ratio is f/6 and above. | Recommended, particularly 6" to 8" apertures. Best from dark sky sites. | (1) Recommended. (2) Recommended in 6” and 8” apertures at f/6 and below. | Not suitable. |
10" and larger equatorial mount Newtonian reflectors | Acceptable, if an aperture mask or eyepiece filter is used to reduce glare. | Highly recommended, if used from dark sky sites. | (1) Acceptable. (2) Highly recommended. | Not suitable. |
6" and larger altazimuth mount Dobsonian reflectors | Acceptable, but an aperture mask or eyepiece filter is recommended if 10" or larger. | Highly recommended, 10” and larger best used from dark sky sites. | (1) Not suitable. (2) Not suitable. | Not suitable. |
Catadioptric Telescopes | Will the instrument be used primarily for lunar and planetary observing? | Will the instrument be used primarily for deep space observing? | Will the instrument be used for (1) lunar and planetary or (2) deep space photography? | Will the instrument be used for terrestrial viewing during the daytime? |
5" to 9¼" Schmidt-Cassegrains | Recommended in all sizes, from all observing sites. | Recommended, particularly 8" aperture and larger from dark sky sites. | (1) Recommended. (2) Particularly recommended in larger sizes. | Suitable in smaller sizes, if it can be used in altazimuth mode. |
10" and larger Schmidt-Cassegrains | Acceptable, but performance usually limited by seeing conditions. | Highly recommended, but best if used from dark sky sites. | (1) Recommended. (2) Highly recommended. | Generally not suitable for daytime use. |
3.5" to 7" Maksutov-Cassegrains | Highly recommended. | Dark skies and 7" aperture needed for best performance. | (1) Excellent. (2) Acceptable in 7", but long focal ratio a drawback. | Suitable in smaller sizes, if can used in altazimuth mode. |
Binoculars | Will the instrument be used primarily for lunar and planetary observing? | Will the instrument be used primarily for deep space observing? | Will the instrument be used for (1) lunar and planetary or (2) deep space photography? | Will the instrument be used for terrestrial viewing during the daytime? |
35mm to 70mm binoculars | Acceptable to good for lunar. Not suitable for planetary. | Respectable performance in 50mm to 70mm sizes, adequate in 42mm and below. | (1) Not suitable. (2) Not suitable. | Very suitable in all sizes. |
80mm and larger astronomical binoculars | Acceptable to good for lunar if tripod mounted, somewhat usable for planetary in higher powers. | Good performance on large scale objects. | (1) Not suitable. (2) Not suitable. | Suitable, if tripod mounted. |
Spotting Scopes | Will the instrument be used primarily for lunar and planetary observing? | Will the instrument be used primarily for deep space observing? | Will the instrument be used for (1) lunar and planetary or (2) deep space photography? | Will the instrument be used for terrestrial viewing during the daytime? |
Refractor spotting scopes on photo tripod | Acceptable, except difficult to track at high powers. | Limited deep space use in small apertures; respectable in larger sizes. | (1) Marginally useful, but not recommended. (2) Not suitable. | Very suitable. |
Catadioptric spotting scopes on photo tripod | Acceptable, except difficult to track at high powers. | Limited deep space use in small apertures; respectable in larger sizes. | (1) Reasonably useful for lunar shots. (2) Not suitable. | Very suitable. |