The answer to “what lens to buy?” will vary greatly depending on if you like to do landscape, macro, portrait or street photography. Some suggestions on lens types / focal lengths by purpose are listed below.
Architecture: Wide (17-19mm) Tilt-Shift Lens 17-40mm 28mm Prime 40mm Prime 50mm Prime
Astrophotography: A telescope and camera adapter for distant celestial objects. Telephoto (200mm or longer) for nearby celestial objects (such as the moon). Wide-angle (14mm) with a large aperture (f/2.8 or lower) for night sky photos.
General Use: 18-55mm 24-70mm 24-105mm 35mm Prime 50mm Prime
Macro: A macro lens. Ideally with at least 1:1 reproduction and a longer working distance (usually found in lenses 100mm and longer). Or use extension tubes in combination with a shorter focal length lens, or close-up filters in combination with a longer focal length lens, or reverse a lens.
Portraits: (Wider apertures are better. Look for f/2.8 and below) 50mm Prime 85mm Prime 100mm Prime 135mm Prime 70-200mm
Products, Food, Still Life: 50mm Prime 85mm Prime
Real Estate: 11-24mm 12-24mm 15-30mm 16-35mm 17-40mm 18-35mm 18-55mm 20mm Prime
Sports, Wildlife, Nature: 70-200mm 70-300mm 100-400mm 150-600mm 300mm Prime 400mm Prime 600mm Prime
Street Photography: 35mm Prime 50mm Prime 85mm Prime
Travel: 50mm Prime 70-200mm
Lens choice depends on what you want to shoot. Different lenses are suited for different purposes. Hope this article has helped you understand what to look for when you feel confused to buy lens.