Astro Tutorial #1.6: THE F-RATIO "fast" vs "slow" scopes
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Astro Tutorial #1.5: Focal Length and Aperture
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Stellarium erklärt! Welches Teleskop/Brennweite?
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Astro Tutorial #1.11: Telescope Mounts - ALT/AZ vs EQ
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Focal Length vs. Focal Ratio: What They Do Conceptually! #astronomy #science #telescope
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Are Fast Telescopes Really Better? | Demystifying Astrographs
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The WO Zenithstar 73/430 - A good beginner apochromatic refractor?
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Telescope Optics Testing
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