Refractor telescope Skywatcher BK 909 AZ3 90 mm aperture 900 mm focal length

Skywatcher BK 909 AZ3 is a refractor telescope with a 90 mm aperture and 900 mm focal length mounted on an AZ3 alt-azimuth mount. The optical design and moderate focal ratio deliver clear views of the Moon and planets and allow useful results for bright deep-sky objects. The kit provides a stable, manually operated platform that is suited to visual observing and basic short-exposure astrophotography when paired with a compatible camera or eyepiece adapter.

Advantages

The 90 mm objective gathers enough light for crisp lunar and planetary detail while remaining portable for transport to observing sites. The 900 mm focal length balances magnification and field of view, making it practical for both high-contrast planetary observation and framing brighter nebulae and star clusters. The AZ3 alt-azimuth mount offers straightforward altitude-azimuth movement and a lightweight tripod for rapid setup. Manual controls and simple mechanics reduce maintenance and make the instrument accessible to beginners and hobbyists.

Suitable for

• Visual observation of the Moon and planets
• Viewing brighter deep-sky objects such as open clusters and some nebulae
• Portable backyard astronomy and field use
• Beginner to intermediate amateur astronomers
• Basic short-exposure astrophotography with appropriate camera adapters

Key specifications

• Optical type: refractor
• Aperture: 90 mm
• Focal length: 900 mm
• Focal ratio: f/10
• Mount type: alt-azimuth (AZ3)
• Manual pointing and tracking
• Included tripod: lightweight adjustable tripod
• Suitable for visual observing and short-exposure imaging

How to use

Set up the AZ3 tripod on firm, level ground and attach the optical tube securely. Start with a low-power eyepiece to locate targets and center them in the field of view; then switch to higher magnification for detailed lunar and planetary observation. Use slow-motion controls or manual adjustments on the mount to follow objects across the sky. For short-exposure astrophotography, attach a compatible camera or eyepiece projection adapter and use short exposures to avoid star trailing; ensure the camera is balanced and secured before imaging.