| A visual back, or eyepiece holder, is a 1.25” metal tube that threads onto the 2” opening in the rear cell of catadioptric telescopes to hold 1.25” visual accessories (such as star diagonals and image erectors). A 1.25” visual back is supplied as standard equipment with some, but not all, catadioptric telescopes. A thumbscrew in the side of the 1.25” tube holds the visual accessories in place. The knurled ring that attaches the visual back to the telescope can be loosened to allow the visual back to be rotated to put the thumbscrew in the most convenient position. The outside of the 1.25” tube is threaded to accept a tele-extender for high magnification lunar and planetary photography. Those telescopes that are not supplied with a 1.25” visual back as standard equipment will require one if such photography is planned. For details on how the visual back is used with a tele-extender, see the introductory material under “tele-extenders” in the photo accessory section.
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