Carson RedSight Red LED Flashlight Two Brightness Settings Glow-in-the-Dark Grip Stargazing (SL-33) Review (2026)

Who the SL-33 is for

The RedSight SL-33 is built for stargazers, campers and anyone who needs to read in the dark, such as star charts, maps or gear labels, without the white light that ruins night adapted vision. Its 650 nanometer red LED wavelength is specifically chosen to have minimal effect on rod cells in the eye, the receptors responsible for night vision, making it a purpose built accessory rather than a general flashlight with a red lens taped over it. It suits observers who want an inexpensive, dedicated red light to keep in an eyepiece case or jacket pocket alongside a primary white flashlight for setup tasks.

LED array and brightness settings

Rather than a single bright LED, the SL-33 uses nine smaller red LEDs arranged for even illumination across the beam, paired with two brightness settings that let the user choose a dimmer glow for close up chart reading or a brighter setting for walking around an observing site or campsite. Two fixed settings are less granular than a continuously variable thumbwheel dimmer found on some competing astronomy flashlights, so users who want fine tuned control over brightness level will find the step between the two settings more noticeable than a smooth dial.

Build, grip and portability

The flashlight measures about 1.2 by 1.2 by 3.8 inches and weighs about 2.4 ounces, making it small and light enough to clip to a bag or belt loop using the included carabiner rather than needing to be carried loose in a pocket. Its housing is plastic rather than metal, which keeps the weight and price down but makes it less rugged than aluminum bodied flashlights if dropped repeatedly on hard ground. A glow-in-the-dark green rubber grip is a small but genuinely useful feature for an astronomy flashlight, since it makes the light itself easy to spot on a dark observing table without needing another light source to find it.

Power and everyday reliability

The SL-33 runs on 3 AAA batteries, a very common and easy to replace battery size compared with some flashlights that need less common cells, and AAA batteries are light enough that carrying spares in a coat pocket or eyepiece case adds negligible weight for a multi night trip. Because the light output is modest and spread across nine LEDs rather than driven through a single high output emitter, battery life on typical intermittent astronomy use, such as brief chart checks, should be reasonable, though Carson does not publish an exact runtime figure that buyers can verify independently. The carabiner clip also means the flashlight can hang from a bag zipper between uses rather than being dug for at the bottom of a pocket, a small convenience during a cold, dark observing session.

Verdict and how it compares

This flashlight earns a strong score as an affordable, purpose built red light for protecting night vision, and it ranks just behind Celestron's 93588 Astro Night Vision Flashlight in the red flashlight comparison it belongs to, largely because that competitor offers continuously variable brightness rather than two fixed settings. Buyers drawn to its low price, common AAA batteries and glow-in-the-dark grip will find it a solid entry level choice, while anyone who wants finer brightness control or a more rugged metal body should look at the Celestron model or a headlamp style red light instead.

Frequently asked questions