and short exposure photos, but not good enough for serious astrophotography. Alt-Az mounts require star alignments for the OTA to track stars and they do not have adjustment components on the mount. Equatorial mounts require alignment of the mount components as well as star alignments for accurate OTA tracking.
In order to provide the required Polar Axis alignment, equatorial mounts use a combination of both mount types described above. The adjustable part of the mount moves in the Alt-Az mode in order to align the R.A. axis, also known as the mount’s Polar Axis, with the CNP. These Polar Axis adjustments do not involve any rotations of the OTA about the R.A. or DEC axes and can be performed without the OTA installed. The first step is to make an approximate azimuth alignment of the Polar Axis by aligning the specified tripod leg or reference point toward True North using a compass for reference (you must allow for the variation between True and Magnetic North at your location). Precise horizontal alignment of the Polar Axis is accomplished with azimuth adjustments on the mount. The second step is to adjust the Polar Axis vertically (altitude) above the North horizon by setting the observer’s latitude on the provided latitude scale. This procedure is based on the fundamental geometry of the Earth’s coordinate system in conjunction with the concept of the celestial sphere. You can verify this by visualizing yourself at the North Pole (latitude N90°) and Polaris will be 90° from the horizon, or directly overhead. These steps will place the Polar Axis very close to the CNP. Both of the above adjustments can be enhanced by the use of an opening along the R.A. axis that allows direct viewing of the North Star and the use of a polar scope to view through this opening. If you are going to get the most out of your equatorial mount it is essential to understand the concept of the Polar Axis and how the equatorial mount helps you establish and maintain a true Polar Axis alignment. Now, you are ready to perform star alignments using the equatorial mount’s electronic controller and enjoy the night sky.
The iEQ75-GT is a next-generation equatorial mount that provides the precision alignment capabilities required for today’s complete astronomy solution. The following sections of this manual provide the detailed steps required to successfully set up and operate the iEQ75-GT.
2.5. iEQ75-GT Assembly
NOTE: The iEQ75-GT is a precision astronomical instrument. It is highly recommended that you read the entire manual and become familiar with the nomenclature and function of all components before starting the assembly.
STEP 1. Setup Tripod
Expand the tripod legs and install the Tripod Support using the Tripod Lock as shown in Figure 7. Tightening the Tripod Lock will expand the tripod legs fully and provide maximum support for the mount and the Optical Tube Assembly (OTA). Adjust the tripod height by unlocking the tripod Leg Lock Screws, sliding the lower tripod leg to the desired length, and relocking the tripod Leg Lock Screws. It is recommended that you extend the legs fully during the first assembly and modify the length as required in subsequent adjustments. After the legs are adjusted and locked, stand the tripod with the Alignment Peg facing True South. If you are located in the southern hemisphere, face the Alignment Peg True North.
STEP 2. Attach the iEQ75-GT Mount
Locate the Azimuth Adjustment Knobs and retract them to allow enough clearance for the mount to fit on the tripod head. Unscrew the four (4) Azimuth Locking Screws shown in Figure 8. Place the mount onto the Tripod Head with the alignment notch on top of the Alignment Peg. Place the four (4) Azimuth Locking Screws back and tighten the screws. Level the tripod base by adjusting the individual legs. You need a level to check leveling.
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