What is an Erecting Eyepiece?
An erecting eyepiece or image erector is an accessory which compensates for the upside-down and backwards image that a telescope normally delivers, producing properly oriented images (as seen with the naked eye), best suited for land or terrestrial viewing. Most image erectors also increase the effective focal length of the objective lens or mirror of the telescope by the accessory’s stated factor. The erecting eyepiece, like the Barlow lens, is placed between the objective and the eyepiece (in the eyepiece holder), effectively increasing the magnification power of the eyepiece used by the factor stated (1.5X or 2X, for example).
