These are the best prime lenses for astrophotography when you want pin-point stars, disciplined coma and sagittal astigmatism, even illumination, and coatings that keep contrast under light pollution—whether you’re shooting Milky Way landscapes, tracked mosaics, or telephoto nebulae—and here’s what to look for as you buy: prioritize fast apertures with clean corners at working stops (ƒ1.4–ƒ2.8, usually best 1/3–1 stop down), tight coma control in the extreme corners, low sagittal flare around bright stars, gentle field curvature, repeatable infinity focus with a long, smooth MF throw (or a reliable hard stop), minimal focus breathing if you film, and a practical filter plan (front 67/77/82mm threads or proven rear gels/holders for bulbous fronts); for tracked telephoto work, favor primes with low longitudinal CA and robust collars for balance on a star tracker. Full-frame wide/ultra-wide prime heroes (Milky Way/nightscapes): Sigma 14mm ƒ1.4 DG DN Art (astro specialist with superb corner stars), Sony FE 14mm ƒ1.8 GM (tiny, disciplined coma), Sony FE 20mm ƒ1.8 G and FE 24mm ƒ1.4 GM (versatile, threaded, high contrast), Nikon Z 20mm ƒ1.8 S and Z 24mm ƒ1.8 S (neutral color, tidy corners), Canon RF 24mm ƒ1.8 Macro IS and RF 16mm ƒ2.8 (budget night pair), Laowa 15mm ƒ2 Zero-D and 12mm ƒ2.8 (manual “straight-line” classics), and Samyang/Rokinon 14mm ƒ2.8, 20mm ƒ1.8, 24mm ƒ1.4 (great value once you learn their best apertures). Full-frame mid/tele primes for tracked deep-sky and compressed nightscapes: Sony FE 35mm ƒ1.4 GM (clean for panoramas), FE 50mm ƒ1.4/ƒ1.2 GM (bright star fields), FE 85mm ƒ1.8 / ƒ1.4 GM and FE 135mm ƒ1.8 GM (beloved for nebulae with trackers), Nikon Z 85mm ƒ1.8 S and Z 135mm ƒ1.8 Plena (round stars across the frame), Canon RF 85mm ƒ2 IS and RF 135mm ƒ1.8L IS (IS helps for static foreground blends), Sigma 85mm/105mm/135mm ƒ1.4 DG DN Art (crisp stars with modern flare control), and the Samyang 135mm ƒ2 (legendary astro value); classic 200mm ƒ2.8 primes (Canon EF 200/2.8L II, Nikon 200/2.8) also shine on trackers. APS-C standouts: Sony E 11mm ƒ1.8 (compact ultrawide), E 15mm ƒ1.4 G (sharp 22.5-eq with threads), Sigma 16mm ƒ1.4 DC DN and 30/56mm ƒ1.4 DC DN (clean stars for panoramas and short tele), Viltrox 13mm ƒ1.4 (fast, wide), Fujifilm XF 16mm ƒ1.4, XF 18mm ƒ1.4, XF 23mm/33mm ƒ1.4 LM WR (quiet linear AF, strong wide-open contrast), XF 56mm ƒ1.2 R WR (portrait + astro), and Samyang 12mm ƒ2 (value legend). Micro Four Thirds picks: OM SYSTEM/OLYMPUS 12mm ƒ2 (pocket nightscaper), 17/25/45mm ƒ1.2 Pro (rounded discs, weather-sealed), Laowa 7.5mm ƒ2 (ultralight astro beast), Panasonic Leica 10–25mm ƒ1.7 used as primes across stops, and Panasonic/Leica 42.5mm ƒ1.2 for tracked tele fields. Practical buyer tips: if corner stars matter most, study coma/astigmatism tests—not just MTF; prefer lenses with long, smooth MF throw and clear infinity marks (or reliable hard-stop behavior); standardized front diameters simplify NDs for twilight blends; apodization lenses (e.g., STF) look gorgeous but cost light—better for urban nights than Milky Way; for tele primes on trackers, add an Arca foot/collar for balance and consider a compact guide scope once you pass ~85–135mm. Night-field technique that keeps stars tight: use the NPF rule (more accurate than the 500-rule) to set shutter by focal length and pixel pitch; shoot RAW, disable IBIS/OSS on a tripod, use magnified live view on a bright star and “rock” focus for peak micro-contrast, then tape the ring; start with a high-ISO test frame to nail composition, then drop ISO and expose to the right without clipping foregrounds; stop 1/3–1 stop down from wide open for cleaner corners, run a dew heater or hood to prevent fogging, and bracket a low-ISO foreground at dusk/blue hour for noise-free blends; stack multiple sky frames (Sequator/DeepSkyStacker/Siril) and add calibration frames (darks/flats/bias) for deep-sky with teles; plan around new moon and core rise with a photo-planner, set WB ~3800–4200K for natural skies, and keep cables tidy on trackers. Whether you’re framing a lone tree under the arch, layering tracked mosaics over desert mesas, or isolating nebulae with a fast 135, the best prime lenses for astrophotography combine big apertures, coma-taming optics, and reliable manual focus—so your night images stay bright, sharp, and beautifully star-strewn.