Updated 27 November 2001
Aperture fever has set in and you're beginning to wonder how you will mount that 5" short-tube refractor on your NexStar 60GT mount. Or maybe it is that old C5 tube sitting in the closet. Or perhaps that TeleVue 102 that you've had your eye on. The answer is this bracket from Baader Planetarium.
As of this update, I received the final product from Baader Planetarium and they are now available for purchase in the United States from Alpine Astronomical at: http://www.alpineastro.com. The costs are $65 for the N60/80 mount and $75 for the N114 mount. They are available in Europe directly from Baader (www.baader-planetarium.de). Additional dovetail brackets are available for quickly mounting additional telescope tubes with just a twist of the locking knob. The dovetail brackets are the same dimension as the commonly available brackets on mounts such as the Celestron CG-5, Vixen GP and GP-DX and the various Orion equatorial mounts.
The fit and finish of this product is first-rate. Mechanically it is extremely smooth and the tolerances are much better than the NexStar itself. The final model (these pictures are the prototype) is fully anodized and sports a red locking knob rather than the black knob shown here. This is a good feature to hopefully prevent you from accidentally loosening the locking knob and watching in horror as your $2000 TeleVue slides towards the ground in slow motion!
Installation of the bracket is simple, but you will need a socket wrench to reach the mounting nut. First you begin by opening the tube ring and setting your existing optical tube assembly (OTA) to the side. Then you remove the single large nut holding the tube ring to the mount; note the order of the washers. Remove the tube ring and look for the large fiber washer on the side that mates to the fork arm. You need this washer to provide the necessary slip and friction between the bracket and the fork arm. Use a razor knife or similar to carefully remove the washer. Set the tube ring to the side. These four figures show the N114 mount as through the full assembly:
After removing the tube ring you install the mounting plate (Figure 5) on the NexStar mount. The fiber washer will be positioned on the back side of the mounting plate. If the large gear has any grease in the area where the plate rests you will have problems with slippage, so clean any excess grease if necessary. Same for both sides of the fiber washer. If the gear comes off, you will find three nylon disks on the other side. These must go back into their holders in the fork arm. If you have the N114, you will need to insert the spacer shown in Figure 6 before the plate. Secure the plate using the washers and nut previously removed; tighten a moderate amount - we will adjust the friction setting later. Be sure to at least tighten the nut until the top of the nut is flush with the end of the bolt.
Next, using the two hex bolts provided, attach the dovetail mount (Figure 7) to the plate you previously mounted. Don't bother to tighten these bolts more than hand-tight as we will need to remove the dovetail mount when we adjust the friction of the axis. You can now attach most any OTA desired to the dovetail bracket (Figure 8). The dovetail bracket slides into the dovetail mount (Figure 7) and is held in place by tightening the large knob by hand. You can remove or mount the OTA on the tripod in seconds. You can also slide the OTA back and forth to help balance heavy accessories.
The last remaining step is to adjust the friction of the altitude axis. In addition to the nut securing the Baader Bracket mounting plate (Figure 5), a second nut is found on the end of the altitude axis located on the outside of the fork arm under the plastic cover. To access this second nut, look at the side of the fork arm where the hand controller and power connectors are located. Remove the two screws holding this plastic cover to the the fork arm. It will still be connected by a set of wires, which can remain attached. Look for the large nut at the top end of the fork arm.
To adjust the altitude axis, first, loosen the nut we uncovered on the outside of the fork arm. Then tighten the nut on the OTA side as much as possible - note that you will need to remove the Baader Bracket dovetail mount (Figure 7) to access this nut. Next, tighten the nut on the outside of the fork arm just tight enough that the Baader Bracket mounting plate no longer rocks back and forth. Too tight and the mount may not move freely, tracking will suffer and battery life will be shortened. Apply power to the mount and ensure free movement for 360 degrees. Adjust the nut on the outside of the fork arm again if necessary.
Reattach the Baader Bracket dovetail mount and the OTA and try moving the OTA up and down by pushing on the end of the OTA. It should require moderate force to move the OTA or it might not move at all unless you hear the motor spinning. If it moves easily, pull off the OTA and Baader Bracket dovetail mount and tighten the nut a quarter turn and try again. Continue tightening or loosening until you feel the OTA will stay in place when accidentally pushed.
You will also note that the mounting plate has a dimple stamped on one side. This is to allow you to more easily mark the correct 'orthogonal' position described in the NexStar Alignment Guide available on the home page of this site. You might find it useful to fill the dimple with a contrasting color of paint (black perhaps) to make it more visible under your red flashlight at a dark site.
How well does it work? Baader Planetarium has created another great product! Now for just a few hundred dollars (less if you find an N60GT for sale) you can have a proven and accurate goto mount for just about any moderate-sized telescope tube. Orion is selling good quality, inexpensive Maks up to 127mm as well as a nice short tube 120mm refractor. The Megrez 80 is an extremely hot item at a good price. The various Stellarvue short tube refractors are highly prized. Then there are the aforementioned TeleVue and small SCTs. With the introduction of this bracket, the possibilities are endless.
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