The slotted mounting holes in the base of the piggyback allow it to be installed in pre-drilled threaded holes at the 12 o'clock position on the rear cell of any of these scopes. Existing short screws capping these holes in the rear cell must be removed (and saved) before the piggyback can be installed using the new longer screws provided with the piggyback. Because of the larger radius of curvature of the 11" and 14" optical tubes, there will be a slight gap between the rear cell and the center of the underside of the piggyback. This does not affect performance and is of no consequence if the piggyback mounting screws are threaded firmly in place.

The camera platform of the piggyback is 2.75" tall and there is a standard 1/4"-20 thread bolt with a hand-tighten knob in the platform to hold the camera in place. The camera can be pivoted from side to side to keep the telescope barrel out of the field of view of a wide-angle camera lens, but cannot tilt up and down.

Two sets of mounting screws are provided with the piggyback. The smaller #8-32x1/2” machine screws are used to mount the piggyback on the 8” and 9.25” Celestron scopes. The larger #10-25x5/8” machine screws are used to mount the piggyback on the 11” and 14” Celestron scopes. If the piggyback is removed, the short screws that sealed the rear cell (that were saved when the piggyback was installed) should be used to reseal the mounting holes on the rear cell. Do not use the mounting screws that came with the piggyback to reseal the rear cell holes! These screws are long enough to obstruct the movement of the telescope’s primary mirror and possibly chip it. Damage caused by using incorrect length screws to reseal the rear cell holes is not covered by warranty.

Exposure times with a digital camera will be limited by the build-up of thermal noise within the camera’s electronics, so some experimentation will be needed to see how long an exposure you can take before the image begins to get noisy and show excessive grain. The amount of light pollution in your area may also limit your exposure times.

Generally, with the normal lens on a camera, and the scope tracking in an altazimuth mode, exposure times will be limited to a maximum of five minutes or so for good full-frame images. After that, assuming your digital camera image has not become excessively noisy, the stars at the corners of the image will start to turn into short curved streaks because of the field rotation inherent in an altazimuth mount.

The field rotation and star trails in long exposures can be eliminated by using an optional equatorial wedge to convert an altazimuth-mounted scope to an equatorial tracking mode. In all cases, noise build-up in a digital camera would still limit your exposure times.