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Taurus-Tech Tracker III Off-axis Guider

Posted by Chris Provost   03/01/2005 12:00AM

Taurus-Tech Tracker III Off-axis Guider
First, a little background. I am part of a dying breed of film astrophotographers. To make my adventure even more difficult, I choose to use a Meade LXD 75 10" Schmidt Newtonian. My scope has very limited back focus which makes it impossible to use a conventional off-axis guider.

Yeah I know I can't be a serious astrophotographer with such limiting equipment. The LXD 75 mount is taxed with the big 10" O.T.A riding on top, not to mention the need for a guide scope and 36 lbs of weight to balance it all out. I have some good results using an ST-80 as a guide scope, but the weight issue was "heavy" on my mind. So what do I do?

Well, of course I do what any adult male would do in my situation. I ask Santa Claus to leave a magical astro gadget under the tree. Boy, did the big man ever deliver!

Ole' St. Nick's remedy to my cumbersome astrophotography rig was the Taurus Tech Tracker III. The Tracker III is a combination off-axis guider, focus aid, and view port. This nifty piece of hardware is available with a special mount for Schmidt Newtonians to compensate for the back focus problem.

The Base:

In my case the Tracker III body mounts in place of my focuser, with the ULPF (Ultra Low Profile Focuser) base. Now hold on, I know what you are thinking. You CAN reinstall the focuser very quickly and, as of yet, I have noticed no problems with removing and reinstalling the focuser. The ULPF kit comes with new hardware for the LXD 75 Schmidt Newtonians. This hardware makes it possible to switch between focuser and Tracker III body by only removing 4 short screws. There is no need to disassemble your scope after the initial installation. Collimation does not seem to be affected in any way; the focuser stays very square to the tube and secondary. Again, this means of attachment is only needed with a Schmidt Newtonian or other scope with very little back focus. Taurus Tech offers standard 2" focuser attachments with this model as well.

The Body:

The Tracker III body threads into the ULPF base, allowing you to focus your camera by simply twisting the threaded telescope adapter. It locks down via nylon thumb screw and is very secure. This adapter is held firmly to the body by 4 large nylon thumbscrews. This means of attachment allows you to rotate the body 360 degrees to search for guide stars without changing the focus. The meat of the body consist of two ports. One is a view port; the other is the guider port. The view port serves two very important functions. The first function of the view port allows you to see what the camera sees. This is a great luxury, as trying to frame a nebula with low surface brightness on a matte camera screen is an adventure in pure insanity. The other purpose of this view port and what really, in my opinion sets this off-axis guider apart from the rest is it allows you to make an eyepiece Para focal with your camera! The view port is also capable of extremely fine focusing. Once you have made your eyepiece Para focal with your camera, you use a supplied focus gauge which allows you the comfort of putting the eyepiece right back where it was. The view port must be slide out of the light path before you open the shutter or start imaging unless of course you need that all illusive shot of the back of an optical grade diagonal mirror.

The second port is the guider port. "Same old, same old" you say...wrong! The mirror is very well made. The mirror can slide in and out of the optical path allowing you a much greater selection of guide stars. Still can’t find a guide star? Well, loosen the four thumbscrews near the base, rotate the body a little and voile guide stars! Still nothing? O.k. slide the prism in or out a little...there you go now you should have something. You can use the sliding prism to position your guide star as well. Oh, yeah don't worry about either port falling out they have a channel interlock. No worries! At the head of the body is the T-thread insert. This insert also serves a special function. It like the base of the body is held in place by four large nylon thumbscrews. I see more twisting and turning in the future. Yes, you can loosen the screws and turn the camera mount as well to aid in framing. The T-thread insert and the base plate insert are channeled as well so they can be loosened and rotated and still remain rigidly in place.

Construction & Price:

The entire Tracker III body is constructed of lightweight, high impact formulation of PVC. The mirrors are optical quality 1/4 wave or better, and coated, according to Taurus-Tech. The body contains 2 internal nylon screws to allow you to secure 2" filters in the light path. Now for the price: My setup with the Tracker III body, the T-thread insert and the ULPF adapter for my scope cost around $394.00.


Well, I like almost everything about Taurus-Tech Tracker III. It is extremely well made, light and, so far, a good performer (check out my first photo with it). My only slight dislike is the price. It is a lot of money, but on the other hand it has made my scope lighter and happier, and has performed well. Plus Santa picked up the tab so it's no skin off my back.

Clear Skies,

Chris Provost