Browse by Manufacturers

More Information  · Recommended Accessories  · Images of Some Features Price $4,239.00 List Price $4,995.00 Weight 55 lbs. Warranty 5 years

• Payload capacity: The EM-200 USD has a maximum instrument payload capacity of 40 pounds (18kg), not including counterweights. This allows the use of catadioptric optical tubes up to 10" or 11" in aperture, along with refractors as large as 6" in aperture (such as the Takahashi TOA-150) and reflectors up to 10" in aperture (such as the Takahashi CN-212 or Mewlon 250). However, most astronomers will probably want to limit the instrument payload to about 33 pounds (15kg), to benefit from the increased stability of having a somewhat smaller instrument on an over-sized mount.

• Drive system details: The EM-200 USD has 180-tooth 3.62" diameter bronze drive gears in both right ascension and declination, with a steel right ascension worm and a brass worm in declination. The bronze right ascension and steel declination shafts are 1.6" in diameter.
      The standard equipment dual axis drive motors are built into the chassis to protect them from the elements and reduce maintenance to a minimum. The quartz-controlled r. a. and dec stepper motors operate at a 100 step per second rate, assuring an imperceptible stepping motion during visual observing and imaging. Careful design and machining keeps the periodic error to an exceptionally low +/- 5 arc seconds during each 8 minute rotation of the worm gear. A premium competitive equatorial head that specifies the same low periodic error costs more than twice the price of the EM-200 USD III.
      The motors can be powered by either 12 or 24 VDC. Takahashi has an optional 110/220VAC to 12VDC power supply (#TPS0012) available, as well an optional 110/220VAC to 24VDC power supply (#TPS0024). The 24VDC power supply gives you a faster slewing speed (particularly when used with a Temma-2 Jr or Temma-2 go-to system), but offers no other advantages.
      The supplied hand control provides a variety of user-selected drive correction rates for astrophotography, from 0.1x sidereal to 1.9x sidereal. Four pushbuttons in a diamond pattern control the motion in r. a. and dec, while a red/green LED shows which speed mode is engaged. A nearby switch and pushbuttons change the directional speed from normal/drive correction to slewing (at 50x sidereal when using the base USD III drive), change from northern to southern hemisphere operation, change the drive correction rates, etc.
      The USD III control panel built into the side of the mount contains an on/off indicator; an adjustable brightness control for the internal illuminator of the built-in polar alignment scope; a computer standby switch for connecting to an optional PC and software through the standard RS-232 port; a DC power input port; a hand control port; and an SBIG type ST4/7 autoguider port for self-guided astrophotography.

• Mount details: The EM-200 USD III’s die-cast body is built to be strong, yet reasonably light, to satisfy both stability and ease of portability needs. The complete head, including the two standard equipment 11 pound (5kg) counterweights, weighs only 33 pounds, making transportation and setup easy. Additional counterweights are recommended to balance payloads over 30 pounds. The counterweight shaft retracts into the mount head for more convenient transport. A positive lever lock holds the shaft vibration-free and firmly in place when it is extended for use.
      The mount is designed to operate in both northern and southern hemispheres at latitudes from 20° to 50°. A single large handle in the base of the mount adjusts the mount in altitude, while twin adjustment knobs let you fine-tune the azimuth alignment on the pole over a +/-15° arc.
      The standard equipment illuminated variable-brightness polar alignment finderscope can align the scope on either celestial pole with a 2 arc minute accuracy. The alignment scale on the polar finder’s reticle is accurate through the year 2030 and can be extrapolated beyond that point. There is a built-in bubble level for leveling the mount for the most accurate tracking.

• Setting circles and slow motion controls: Right ascension and declination setting circles, used to help point the telescope at a celestial object by dialing in its coordinates, are standard equipment. The right ascension circle is marked in hours and subdivided in 10 arc minute intervals, while the declination circle is divided into four 90° quadrants, each divided into 10° segments, with each 10° segment subdivided into 2° intervals.

• Tripod: No tripod is provided, but you have a choice of three Takahashi adjustable height wooden tripods that are designed for use with the EM-200 USD III. The #T6002 SE-M medium height tripod is best suited to reflectors and short focal length refractors. The #T6003 SE-L tall tripod is best suited to longer focal length refractors up to the 5.1" f/7.7 Takahashi TOA-130 in size. The #T6004 SE-LL extra-tall tripod is best suited to still longer focal length refractors up to the 6" f/7.33 Takahashi TOA-150 in size.

• Optical tube mounting method: The mount is designed primarily to be used with Takahashi tube rings, as the circular top of the mount has two holes on 35mm centers threaded to accept the M8 metric bolts supplied with Takahashi rings. However, for non-Takahashi scopes, Takahashi makes a saddle plate that mounts on the EM-200 head and holds standard Losmandy D-plate dovetails (#TJD0002). In addition, Losmandy also makes a similar saddle plate (#G11SPT).

• Computer control: The mount is also available with optional factory-installed Temma-2 Jr (#EM200TJ) and Temma-2 (#EM200T2) go-to computers that are designed to be controlled by an external PC or an optional H-P computer hand control (#TTC0001). Slewing speeds under computer control are considerably higher than the supplied USD III hand control. With the Temma-2 Jr system, the mount slews at 120x sidereal using the 12V power supply, and at 250x using the 24V supply. With the Temma-2 system, slewing is at 350x sidereal with the 12V power supply, and 700x with the 24V supply.

If you’re looking for an extremely accurate and capable equatorial mount for very serious big-scope astrophotography, the Takahashi EM-200 USD III equatorial mount should be at the top of your short list.