refractor/reflector

Refractor

Uses a lens as the objective; suffers from chromatic aberration (different wavelengths focus at different points); large perfect lenses are heavy, expensive, and hard to build; generally better image quality, good for smaller telescopes

Reflector

Uses a paraboloid mirror as the objective; no chromatic aberration; cheaper and lighter than large lenses; secondary mirror and its support structure block some light and cause diffraction spikes; slightly lower image quality but standard for large telescopes

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