Refractor:

Advantages:

1. Great classic design 
2. No obstruction 
3. Good contrast 
4. Collimation almost never necessary
5. No thermal degradation

Disadvantages:

1. Expensive at larger apertures
2. Unwieldy with large refractors
3. Chromatic aberration and blurring if it not corrected

Newtonian:

Advantages:

1. Cheap to manufacture 
2. Large apertures possible
3. No chromatic aberration
4. Good contrast 
5. Obstruction is fairly low
6. Light
7. Many variants are available 
8. Dobsonian construction possible

Disadvantages:

1. Bildfehler je nach Öffnungsverhältnis
2. Durch Obstruktion geringerer Kontrast als bei Refraktor gleicher Öffnung
3. Da nicht geschlossen, sind thermische Luftströmungen möglich, die die Abbildung beeinträchtigen.
4. Muss hin und wieder justiert werden
5. Schmutzanfälliger als ein geschlossenes System

Schmidt-Cassegrain, ACF and Edge HD:

Advantages:

1. Short length 
2. Very practical handling 
3. Portable 
4. Viewing is always comfortable
5. The SC thread allows a wide range of accessories to be connected
6. Instruments with a fork mount can be set up extremely rapidly 

Disadvantages:

1. More expensive than a Newtonian of comparable aperture
2. Larger secondary mirror than with a Newtonian telescope

Maksutov:

Advantages:

1. More expensive than a Newtonian of comparable aperture    
2. Short overall length
3. Almost no chromatic aberration
4. Closed system, therefore no thermal degradation
5. Good correction of spherical aberration
6. Very good contrast
7. No spider vanes
8. Inexpensive models available

Disadvantages:

1. Heavy due to the meniscus lens

2. Long cool-down time 
3. Larger apertures (above 8") are rather expensive
4. Obstructed by the secondary mirror
5. Small fields of view due to aperture ratio of about f/13

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Achromatic refractors

Newton reflectors

Maksutov-Optic