Secondary Mirror Skywatcher 150/750 SW-5514 1.25 inch – for 150 mm f/5 Newtonian

Secondary Mirror Skywatcher 150/750 SW-5514 1.25 inch is a replacement secondary mirror element designed for the Skywatcher 150/750 (150 mm, f/5) Newtonian telescope. It redirects the focused light from the primary mirror to a 1.25" focuser and eyepiece, restoring or improving the optical path for visual observing and basic astrophotography. The mirror is compatible with standard 1.25" focuser assemblies used on many Newtonian setups and is intended for tasks such as repair, maintenance, or optical alignment upgrades.

Advantages

This secondary mirror provides a direct and mechanically simple solution to replace or upgrade an existing secondary diagonal in a 150 mm f/5 Newtonian telescope. It supports standard 1.25" eyepieces and accessories without additional adapters, maintains a compact light path suited to fast focal ratios, and helps recover optical performance after damage or wear to the original secondary mirror. The component is straightforward to install and aligns with typical Newtonian secondary holders.

Suitable for

• Replacing a damaged or worn secondary mirror in a 150 mm f/5 Newtonian telescope
• Routine maintenance and optical realignment of Newtonian reflectors
• Upgrading an older diagonal to a standard 1.25" secondary for eyepiece compatibility
• Basic astrophotography where a correct secondary alignment is required

Key specifications

• Mirror size: 1.25 inch (secondary element sized for 1.25" focuser compatibility)
• Intended telescope type: Newtonian reflector with 150 mm aperture and f/5 focal ratio
• Optical function: Redirects light to eyepiece/focuser; functions as secondary diagonal element
• Mount compatibility: Fits standard 1.25" focuser assemblies and typical Newtonian secondary holders
• Primary uses: Visual observation and basic astrophotography support

How to use

Remove the original secondary mirror or diagonal according to your telescope's disassembly instructions, taking care to mark and preserve the existing alignment if desired. Mount the replacement secondary mirror in the telescope’s secondary holder or diagonal assembly and perform a careful collimation procedure to align the secondary with the primary mirror and focuser axis. Insert a 1.25" eyepiece or camera adapter into the focuser and verify focus and field illumination. If necessary, repeat fine collimation steps while observing a star or using a collimation tool.

Recommendations

Handle the mirror by the edges and avoid touching the optical surface. Use a soft blower and lens tissue or dedicated optical cleaner for any dust or smudges. After installation, always perform full collimation on the Newtonian optical train, especially for fast f/5 systems where alignment tolerance is tighter. For imaging, confirm backfocus and camera spacing to maintain proper focus and field coverage.