| This multi-scale/multi-purpose 12.5mm focal length guiding eyepiece is a true classical Abbé-type orthoscopic design for exceptional image sharpness and contrast. It is fully multi-coated for higher light transmission than other illuminated reticles that are merely “coated" or “fully-coated." Its ultra-fine laser-etched reticle allows you to guide on fainter and more sharply focused stars than conventional engraved crosshair reticles, where a guide star must often be defocused to make its seeing disc large enough to avoid being masked by the coarser conventional crosshairs. The reticle can be used for direct guiding on stars outside the center of the field of view, using its off-center single crosshair and quintuple concentric circle guiding reticle. It can also be used for indirect guiding on objects moving in orbits other than east to west, such as asteroids or comets. The elaborate laser-etched multi-function reticle pattern allows many more activities than simply photographic guiding, however. It has very precise reticle scales that allow easy measurement of position angles and linear sizes. For example, binary star separations can be measured to an accuracy of 2 arc seconds and position angles to an accuracy of 1 degree with a 2000mm focal length telescope. It has dual opposed circular scales for measuring position angles that are marked in 5 degree divisions and are labeled every 30 degrees for use with both inverting (reflector) and mirror image (star diagonal) telescopes. Its 60-division linear scales can be used to measure the diameters of lunar craters, cometary comas, sunspots, and planets; binary star separations or the length of a comet’s tail; as well as solar prominence heights, periodic error in a telescope’s drive, a telescope’s true focal length, and more. Unlike three-element Kellner or modified achromatic designs, the four-element Celestron has no internal reflections or ghosting to interfere with measurements of bright objects with high contrast, such as lunar crater diameters. The Micro Guide has a good 42 degree apparent field of view. Its 11mm usable eye relief, the longest of any illuminated guiding reticle that we carry, allows relatively unvignetted use by eyeglass wearers. It includes a removable soft rubber fold-down eyeguard to shield the observer’s eye from ambient light and improve his or her ability to see faint guide stars. Also included is a very detailed 12-page instruction manual. The supplied cordless LED illuminator has a rotary on/off switch with an integral brightness level control. The illuminator uses two common 1.5 volt LR-44 alkaline camera batteries (included) or their equivalent. The Celestron Micro Guide works with virtually any telescope or off-axis guider.
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