Telescope Maksutov-Cassegrain Sky-Watcher BKMAK 127 SP OTA — 127 mm aperture, 1500 mm focal length

The Sky-Watcher BKMAK 127 SP OTA is a Maksutov-Cassegrain optical tube assembly with a 127 mm clear aperture and a 1500 mm focal length. Its compact folded optical design delivers a long focal ratio in a short tube, making the instrument suitable for high-magnification visual observing of the Moon, planets and double stars, as well as for high-contrast imaging of smaller deep-sky objects when mounted on a stable tracking mount. The OTA includes a rigid tube, corrector lens, secondary mirror assembly and a focuser compatible with common mounting rings and dovetail bars.

Advantages

The Maksutov-Cassegrain design provides excellent on-axis sharpness and good correction of spherical aberration in a compact form factor, offering a long effective focal length without long physical tube length. The 127 mm aperture balances light-gathering ability and portability, while the optical configuration produces high-contrast images with reduced coma and minimal need for frequent collimation. The tube’s mechanical construction supports common accessory attachment and integration with standard mounts for visual use or astrophotography.

Suitable for

• High-magnification planetary and lunar observation
• Resolving close double stars
• High-contrast imaging of small planetary nebulae and compact deep-sky targets
• Portable observing sessions and field use with a suitable mount

Key specifications

• Aperture: 127 mm clear aperture
• Focal length: 1500 mm
• Optical type: Maksutov-Cassegrain (folded optics)
• Focal ratio: f/11.8 (approximate)
• Tube type: rigid OTA with corrector plate
• Focuser: visual/astrophotography compatible focuser (suitable for standard eyepiece holders and camera adapters)
• Typical uses: visual observing and astrophotography when used with an appropriate mount and adapters

How to use

Attach the BKMAK 127 SP OTA to a stable equatorial or alt-azimuth mount rated for the instrument’s weight and intended tracking. Use matching mounting rings or a dovetail plate to secure the tube. For visual observing, insert eyepieces into the focuser and achieve focus by adjusting the focuser knob; start with a low-power eyepiece for target acquisition, then move to higher magnification. For astrophotography, attach a suitable camera adapter and backfocus-correcting extension if required by your camera, balance the mount, and use guiding or accurate tracking to obtain long exposures.

Usage recommendations

For best results, use the OTA on a rigid mount with precise tracking for planetary imaging or long-exposure astrophotography. Allow the telescope to reach thermal equilibrium with the outside air before high-magnification observing to reduce image distortions. Use a planetary camera or small sensor DSLR with appropriate Barlow or focal reducer only if backfocus and image scale are correct; consult mount and camera specifications when planning astrophotography setups.