Tandem Guidescope Aiming Device (TGAD) For Tandem and Triad Telescope Mounting Bars Alighning two telescopes can now be easy. No need for shims and endless trial and error. With a TGAD you just aim while looking through the one scope and tighten the knobs. Done. Learn More Sorry, Sold Out Due to changes at the machine shop with my cousin's retirement, I will be selling off existing stock, but not replacing it. Sold Out TGAD with integrated Dove8 Saddle: $485.00 Black Anodized New version of the Tandem Guidescope Aiming Device (TGAD) that has a Dove8 machined into the top to save weight and cost Sold Out TGAD with integrated Dove8 Saddle: $485.00 Clear Anodized New version of the Tandem Guidescope Aiming Device (TGAD) that has a Dove8 machined into the top to save weight and cost Sold Out TGAD with Standard Top: $365.00 Black The top has mounting holes for my standard saddles, or a Takahashi clamshell ring. Image Not Available Sold Out TGAD with Standard Top: $365.00 Clear The top has mounting holes for my standard saddles, or a Takahashi clamshell ring. Sold Out Dove8 Top Only: $130.00 Black New TGAD top that has the Dove8 saddle machined into it. Use this to replace the top on an older TGAD. Sold Out Dove8 Top Only: $130.00 Clear New TGAD top that has the Dove8 saddle machined into it. Use this to replace the top on an older TGAD. New: TGAD with Dove8 saddle integrated into top plate. See Larger Image: Clear Anodized, Black Anodized The new top for the TGAD has a Dove8 saddle integrated into it. The top plate and saddle are machined out of one piece of aircraft aluminum. Instead of bolting a saddle on top of the standard TGAD this one is ready to hold Losmandy D compatible dovetail bars. This design saves weight, lowers the OTA slightly, and saves a little money. If you want to mount a Takahashi clamshell, order the TGAD with the standard top. If you have an Astro-Physics sliding bar on your OTA (SB800, SB1000, SB1500), order the TGAD with the standard top, and my DoveAP saddle. The Tandem Guidescope Aiming Device (TGAD) is designed to be used for aiming a guidescope or second imaging OTA on a tandem bar or triad bar. It can also be used to align an OTA* to be orthogonal to a mount for accurate goto pointing. *The OTA should be mounted on a tandem bar. The TGAD was not designed to attach directly to a mount because there would not be room for the adjustment knobs. For the same reason, it will not work in a piggyback position. Note: The illustrations below were taken sometime ago. Since then, there have been a few changes. The TGAD now comes with short knobs in positions A & B (below). This is to solve a clearance problem on some setups. The images above show the current knob sizes. If you already have a TGAD and want short knobs, order them here. A and B knobs are for altitude adjustment. There are two precision balls (from ball bearings) between the bottom and middle plate. The balls act as a fulcrum for the upper plates -- allowing them to tilt, but remain solidly in place. The link G connecting the bottom and middle plates prevents the plates from coming apart if A and/or B were to become too loose. To raise the altitude of the OTA, loosen knob A and tighten B. To lower the altitude, tighten A and loosen B. All three anodized aluminum plates are milled with a web pattern to reduce weight and maintain strength. Brass seats are used in the bottom and middle plates to capture the fulcrom balls. The illustration below is of the top side of the bottom plate. The four holes forming a square pattern are used to bolt it to a tandem bar. M in the illustration below points to the four holes for mounting the TGAD on a tandem bar as seen from the bottom side of the bottom plate. C, D, and E control Azimuth. C & D clamp the middle and top plates together to lock the azimuth position. E controls the azimuth adjustment with stainless steel threads and a brass pusher. Loosen C & D and turn E to adjust azimuth. The F nuts allow you to adjust the backlash in the azimuth adjustment threads. This is only important for the aesthetics of using the adjustment knob. The azimuth rigidity during imaging is assured by the lock-down knobs C & D. To attach an OTA to the TGAD, mounting holes are provided form my saddles (M) and Takahashi EM clamshell rings (EM). The illustration below shows a Dove12 with red knobs attached to the top of the TGAD. Note the clear anodized azimuth adjustment knob of the TGAD showing from behind the Dove12.

Sample Photos from Gary Law Gary tested one of the prototypes of the Tandem Guidescope Aiming Device (TGAD). Here are a couple images created while using it. Click on images for larger versions. M31 "...a composite image taken with an FSQ106 and BRC-250 of M31. At the time I had both scopes mounted side by side with the FSQ on the [TGAD prototype] aiming device. I collected the data for the composite over two nights simultaneously." "The Rossette nebula from the BRC-250 with the same set-up using the aiming device for the guider."

Early astro image by Bill Patterson using prototype TGAD "It [TGAD] presents an excellent and solid platform for the scope. The adjustments were smooth and precise allowing me match the FOV's on my two scope/ccd combinations." -- Bill Patterson

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