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Accessories and Options Mounts Mount Control Systems Telescopes


The two most important considerations in mount design and construction are maximum strength and rigidity for a given size and accuracy of the drive system. Without this basic foundation, all other features of a mount are just superfluous frills.

The Astro-Physics mounts are all available with either the Servo Micro-Drive Control (SMD) or the Astro-Physics "GTO" computer keypad (and "DigitalSky Voice" software) control electronics. These systems have been engineered incorporating the advantages of years of experience and design of synchronous and stepper electronics with geared drive systems, combined with the latest innovations in servo motor and controller circuitry.

The "SMD" controller is intended for those observers who enjoy searching for objects in traditional ways: star hopping, engraved setting circles, or digital setting circles / aids to Celestial Navigation, etc. Basic functions that are included are: selection of tracking and guiding (or centering) rates, PEM (Permanent Error Memory) to reduce periodic errors typical of worm gears to virtually an imperceptible amplitude, declination backlash control, N-S-W-E directional control buttons with control switch reversal, user selectable ability to operate in either North or Southern hemispheres, adjustable power output for accessories such as guiding eyepiece illuminators. The hand controller contains a Telescope Interface Connector ("TIC") socket for CCD Star Tracker/Imaging Camera Systems such as our Santa Barbara Instrument Group (SBIG) "ST" series. Most of the SBIG CCD systems will allow you to auto-guide astronomical film photos, and explore CCD imaging thereby rendering the invisible - obvious.

The Astro-Physics SMD electronics feature a new low current draw, reversible servo motor drive system on both the Right Ascension (R.A.) and the Declination axes. These motors and gears systems are the same as those furnished with the GTO computer control system with hand held keypad controller and "DigitalSky Voice" control system software (PC computer optional). So one can purchase the SMD version of a mount head with the furnished SMD hand controller, and then later at your convenience can upgrade to the GTO full computer control with keypad hand control (for use in the field independent of a personal computer) and also employ the "DigitalSky Voice" control system - all without the need to return the mount head to Company Seven or to Astro-Physics for any modifications.

It will be possible in the future to retrofit the QMD stepper motor driven mounts with the SMD and GTO motors and electronics. However, as the cost s likely to exceed $1,400. (U.S) then it is likely to be more cost effective to trade in or to sell the older mounts and then apply the proceeds to buy the new mount. As the SMD and GTO mount drive motors and controller cost more than the QMD (the QMD mounts had not experienced a price increase in the two years prior to the introduction of the SMD):

  1. As the demand for good used mounts tends to remain high, and the Astro-Physics products remain very well regarded and durable, then the resale value of an older mount might be discounted only 10-15% off of the original selling price.

  2. The model 400 QMD mount will remain in production for now.

    We suggest that if you are interested in employing furnished encoders with our optional digital displays such as our JMI "Max" series of CPU's, then you might find the cost and performance differences may favor upgrading your choice of the "SMD" mount to the "GTO" system at the outset.


  • Hand held push-button controller. Usable even when wearing gloves.
  • Professional quality components (aircraft grade PC board, etc.).
  • Operable in all conceivable temperature ranges.
  • Zero cogging servo motors on both R.A. and Decl. axes.
  • Gears and motors are fully enclosed.
  • Directional N-S-E-W control buttons.
  • User selectable fine guiding or slewing speeds (of up to 64x sidereal).
  • R.A. and Declination reversing switches for consistent object orientation and movement in the eyepiece.
  • PEM - Periodic Error Memory correction; user programmable to correct for any worm induced periodic errors.
  • User selectable Declination Backlash Control.
  • Adjustable voltage output for accessories such as a guiding eyepiece illuminator.

Controller Dimensions 7.25" x 3" x 0.9"
Drive Rates King, Lunar, Sidereal, Solar
Guide/Slew rates 0.25x, 0.5x, 1x, 8x, 64x Sidereal
Hemisphere of Operation North or South (user select able)
Power Consumption 0.4 amps at Sidereal rate
Power Requirements 12 Volts, DC
Power Supplies AC to 12 Volts DC Converter (3 Amp Min.)
Portable Power Packs 12vdc (Minimum 6 Amp Hr.)


Please see the accompanying information sheets for descriptions:


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