Refractor telescope Skywatcher Coma Concealer SW-5407 2 inch accessory

The Skywatcher Coma Concealer SW-5407 2 inch accessory is an optical corrector designed to reduce coma in fast refractor and parabolic mirror telescopes. Installed between the focuser and the eyepiece or camera, the coma concealer improves off‑axis star shape and field illumination, producing tighter, rounder stars toward the edge of the field. The unit fits a standard 2‑inch focuser and is intended for visual observing and astrophotography where improved image quality across the field is required.

Advantages

The coma concealer corrects off‑axis aberrations, particularly coma, so stars remain round and sharp from center to edge. It maintains full 2‑inch aperture and field while providing a flat, better‑illuminated image plane for cameras and eyepieces. The accessory is compact, mechanically robust, and simple to install in a 2‑inch focuser or visual back without additional adapters in many setups.

Suitable for

Key specifications

How to use

Insert the coma concealer into the 2‑inch focuser or visual back and secure it as you would a standard 2‑inch eyepiece or adapter. For visual use, place the eyepiece into the concealer and focus normally; some fine focus adjustment may be required to achieve optimal star shapes at the field edge. For imaging, attach the camera to the concealer using the appropriate T‑ring or camera adapter and adjust backfocus according to the camera‑maker’s specifications. Verify focus across the field and make small position or spacing adjustments between camera and concealer if needed to minimize residual aberrations.

Recommendations

Use the coma concealer on telescopes with fast focal ratios where coma is visible. Perform a series of test exposures or visual checks after installation to determine the best spacing for your specific camera or eyepiece. For astrophotography, check illumination and star shape across the sensor and, if possible, take calibration frames under similar conditions to maximize image quality.