iOptron Stereo Equalizer #3500, Stereo Equalizer #3520 User Manual


SkyGuider™ Tracking Equatorial Mount

Instruction Manual

Product #3500 and #3520




Looking at or near the Sun will cause instant and irreversible damage to your eye. Children should always have adult supervision while observing.

1.SkyGuiderTM Tracking Equatorial Mount Overview

Thank you for choosing the new iOptron SkyGuiderTM Tracking equatorial mount for astrophotography. This portable mount makes it easy to take long exposures of the night sky without streaking or star trailing.

The SkyGuiderTM mount is simple to set up. Just attach the mount to a tripod. Mount your digital camera or lightweight scope onto the mount and balance it. Align the mount to the Pole Star using the included AccuAligningTM dark field illuminated polar scope and an optional smart phone App. Then turn on the motor and it will keep your camera tracking at the same speed the earth rotates. The unique DC servo motor keeps your camera in motion to avoid star trails and allows you to take long exposures for beautiful images of the night sky. A built-in ST-4 compatible guide port will enable you to use autoguiding and make the tracking even better!


Accepts cameras weighing up to 11 lbs (5 kg)

Capable for dual mount application up to 11 lbs (5kg) + 7.7lbs (3.5kg), balanced

Spring loaded gear system with customer adjustable loading force

Auto-tracking for smooth camera motion perfect for long-term exposures

Four pre-set tracking speeds with northern/southern hemisphere selection

Includes iOptron AccuAligningTM dark-field illuminated polar scope for Quick Polar Alignment

Built-in ST-4 compatible guide port

Padded carry bag included

1.5” stainless steel short field tripod with padded carry bag (#3500 only)

Optional ball heads available separately (#3305)

Optional AC/DC adapter (#8417)

Optional 1.5” stainless steel regular height tripod (#3521)

DO NOT hold and swing the counterweight shaft rigorously. This will degrade the performance of the spring loaded gear meshing system and possibly damage it.

The Tension Adjuster is used as the last step to lock, and the first step to release the gears. When disengaging the gear system, release the Tension Adjuster first. Then turn the Gear Switch to OPEN position. When engaging the gear system, turn the Gear Switch to LOCK position first. Then tighten the Tension Adjuster.

Never fully tighten the Tension Adjusters during operations. Fully screw in the Tension Adjuster and then back out by from half a turn to about 2 turns. The optimum spot varies with actual conditions, but is mostly within 2 turns from the fully tightened position. Ideally, it should be at a position just deep enough to eliminate any free movement (“play”), while any force on the worm assembly is kept at a minimum.

2.SkyGuiderTM Tracking Equatorial Mount Assembly

2.1. Introduction

You have just purchased a tracking equatorial mount that is capable of taking you to a new level of astrophotography. When the polar axis of the SkyGuiderTM mount is aligned with the celestial North Pole (CNP), or celestial South Pole (CSP), the mount will evenly match the Earth’s rotation against the sky. Since all celestial objects appear to rotate around the CNP, or CSP—the polar alignment allows the mount to “track” with the celestial sphere and provide accurate tracking for visual observations and astrophotography.

The AccuAligningTM polar scope, along with the Quick Polar Alignment procedure, provides a fast and accurate polar alignment for the mount. A built-in ST-4 compatible guide port will enable you to use autoguiding for highperformance tracking.

The SkyGuiderTM mount is designed for wide field astrophotography. The following sections of this manual provide detailed steps to successfully set up and operate the SkyGuiderTM mount.

iOptron Stereo Equalizer #3500, Stereo Equalizer #3520 User Manual

2.2. Parts List1

The SkyGuiderTM comes with either a mount only (#3520) or as a package (#3500) with mount and a short field tripod.

#3520 SkyGuiderTM Mount Includes (Figure 1):

SkyGuiderTM Tracking equatorial mount with AccuAligningTM polar scope

Padded carry bag

Counterweight shaft

One 3.5 lbs (1.5kg) counterweight

A short latitude adjust knob for low altitude

#3500 SkyGuiderTM Mount Package Includes (Figure 2):

#3520 SkyGuiderTM mount

#3501 1.5” stainless steel short field tripod with padded carry bag

Figure 2. Parts for a #3500

SkyGuiderTM mount package

Figure 1. Parts for a #3520 SkyGuiderTM mount


The following parts are needed to take astrophotography but are not included in the package:

Power source provided by a battery pack or an AC/DC adapter (#8417)

Ball head adapter (#3305)

DLSR camera

Tripod (for #3520)


iPhone/iPad app for accurate polar alignment ( scope/id564078961?mt=8)

Or other application/program to calculate the pole star position. Please refer to the FAQ section under “Support” at for more information.

1 US market only. Actual contents and appearances may vary.


ONLINE CONTENTS (click under “Support” menu)

This manual

Tips for set up

Reviews and feedback from other customers

2.3.Assembly Terms

3/8” 16 screw

Tension adjuster

DEC adapter

Polar axis cover

Polar scope cover



lock screw


Az. Adj. Screw

CW shaft

Center rod with knob

Tripod support tray

Tray locking knob

Figure 3. SkyGuideTM mount with tripod

2.4. SkyGuiderTM EQ Mount Assembly

NOTE: The SkyGuiderTM mount is a precision astronomical instrument. It is highly recommended that you read the entire manual and become familiar with the nomenclature and functions of all components before starting the assembly.

WARNING: Please DO NOT hold and swing the counterweight shaft rigorously. This will degrade the performance of the spring loaded gear meshing system and possibly damage it.

WARNING: The new Gear Switch will allow you to have more precise weight balance. This also means the mount will swing FREELY when the Gear Switch is disengaged. Always hold the mount when releasing the Gear Switch or adjusting the gear tension.

NOTE: The mount is shipped with the latitude setting at high range (35º ~ 60º). If your site latitude is lower than 35º please switch the latitude range before using.

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