Attaching the Telescope to the Mount

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Attaching the Telescope to the Mount

The next step is to attach the telescope (the OTA, or Optical Tube Assembly) to the mount. If you purchased OTA and mount together this will be straight forward. If you purchased them separately, you may have some one-time work to do to work out how to attach them, possibly including purchasing or making adaptor plates of various kinds.

Your attaching mechanism will probably be one of two broad types: rings or dovetail.

Mounting Rings

Mounting Rings are one or two circular clamps that surround and gently hold the optical tube. The rings are, themselves, drilled and threaded, and there will be threaded screws on the mount head to attach to the rings.

Mounting rings open like C-clamps, and are softly padded on the inside. Outside, they have multiple threaded holes to provide a variety of mounting options. rings-loose.jpg
They are designed to surround the OTA and hold it gently but firmly. rings-on-sv80s.jpg
On some scopes, a single, very wide ring is used instead of a pair of rings. Such a ring is called a clamshell. clamshell.jpg
Install the rings on the mount first, using the screws supplied. Make sure they are very well squared to the mount and securely tightened. rings-on-m4.jpg
Then gently place the OTA in the rings and gently tighten the clamps. sv80s-on-m4.jpg

Dovetail Mount

A dovetail mounting system is a quick-disconnect system that may be used alone or may be combined with mounting rings.

The top surface of the mount is a block of metal with a female dovetail slot and a locking screw.This photo shows the female dovetail found on Vixen, Synta, Celestron, EQ-5, and many similar mounts. cg5-dovetail-slot.jpg
A male dovetail plate is either fastened directly to the OTA, or to the mounting rings. cg5-dovetail-plate.jpg
This dovetail plate is attached directly to the OTA, . . . c925-dovetail-my.jpg
while this dovetail plate is attached to a set of standard mounting rings. cg5-dovetail-adapter.jpg
The dovetail plate, with OTA or mounting rings attached, is then inserted into the dovetail slot on the mount. cg5-dovetail-rings.jpg
When the locking screw is tightened, the result is a very secure attachment. sv105-on-cg5.jpg
On some systems, there is a "top" and "bottom" to the dovetail plate. The top has a safety screw, which protrudes from the plate and will prevent it from sliding downward out of the mount if you let go after forgetting to tighten the locking screw on the mount. G11-safety-screw.jpg
If your OTA and mount are mismatched, you can almost always buy or build some kind of adapter. For example, on this homemade adaptor an aluminum plate holds mounting rings on one side and a short section of dovetail stock on the other, allowing a Stellarvue refractor to be mounted on a Celestron CG-5 dovetail mount. Rings-to-cg5 adaptor


Caution: whatever the mechanism for attaching your OTA to the mount, be certain you don't let go of the tube until you are sure all the appropriate locking knobs are tight: both the lock holding the tube to the mount and the locks stopping the mount from rotating on either the Right Ascension or the Declination axes. If you don't tighten these, the mount may suddenly flop to the side, possibly damaging your telescope.


Back: Assembly
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