Celestron 10mm Plossl Reticle Eyepiece.

Guiding (or reticle) eyepieces are mandatory for guided astrophotography. They keep a guide star stationary during long exposures to avoid star trailing. This 5-element guiding eyepiece has a reticle pattern that is a .0075" double spaced line system. The optics are multicoated for increased contrast and have long eyerelief. The high power is ideal for guiding and it has a 50° apparent field of view. This type of reticle pattern allows you to position the guide star in the middle square or at the intersection of two lines, whichever is easier for you. An optional illuminator is required.