Explore Scientific focal extenders work like a premium Barlow lens, multiplying the effective focal length of your telescope to increase the magnification of any eyepiece you own. A 2x focal extender, for example, doubles the magnification of each eyepiece, effectively doubling the size of your eyepiece collection and giving you close-up views of lunar craters, planetary detail and tight double stars.
Unlike basic Barlow lenses, our focal extenders use a telecentric design that helps maintain eye relief and field illumination, so eyepieces stay comfortable to use at higher power. Available in 1.25-inch and 2-inch sizes and multiple magnification factors, they are also useful for planetary imaging, where a longer effective focal length helps capture finer detail on Jupiter, Saturn and Mars. Adding a quality focal extender is an affordable way to expand your magnification range without buying additional eyepieces.
When choosing a focal extender, consider the focal lengths of eyepieces you already own and avoid duplicate magnifications. For example, a 2x extender turns a 24mm eyepiece into the equivalent of a 12mm, so pairing it with 24mm and 14mm eyepieces gives you four useful magnifications. Higher factors such as 3x and 5x are best for planetary viewing and imaging on steady nights. Focal extenders work with refractors, reflectors and catadioptric telescopes, and they are one of the most cost-effective accessories for expanding your observing options.
