William Optics ZenithStar 103 f/6.9 with EQ35 Mount Package

    ZenithStar 103:
  • An f/6.9 FPL53 Doublet Air-Spaced APO
  • Housed in a CNC Machined Ultra-High Precision Lens Cell
  • An x 0.8 Flattener
  • 2.5-inch Rack-and-Pinion Robust Focuser, Dual Speed = 1:10
  • There is no image shifting!


  • Sale
  • Regular price $2,398.00

More on the Way* We do not currently have this in stock, but is a common item we carry. More are likely on the way as the manufacturer allows.
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William Optics ZenithStar 103 f/6.9 with EQ35 Mount Package

The ZenithStar 103 (4.06-inch) aperture f/6.9 imaging APO is made in three colors: Gold, Blue, and Red. It has an innovative Bahtinov Mask Cover (Patented) included!

This beautiful scope has everything you could want from a refractor such as extreme sharpness for clear details and APO color correction. It has all the benefits of the ZenithStar family at a price that is hard to beat.

The William Optics ZenithStar 103 features an f/6.9 FPL53 Doublet air-spaced APO in a CNC machined ultra-high precision lens cell. With an x0.8 flattener, this can also become an f/5.5.

Comes with 2.5-inch rack-and-pinion ultra-robust focuser with 1:10 dual speed

Thanks to its design, there is NO image shifting, making this a real treat to use in astrophotography!

Despite its 103 mm objective, the scope is still very compact and solid. Many airlines will accept it as carry-on luggage! Perfect size for serious observations of deep sky objects and planets. Solar observations are possible with proper additional equipment.

WO-EQ35 PRO Mount 

This mount offers the versatility of two specific mounts in one system as a fully computerized Go-To equatorial mount and a lightweight photo imaging mount. This is perfect for travel and DSLR imaging of the night sky for both beginners and experienced astronomers.

In the standard configuration mode with DEC and RA axes, you can use it as a computerized Synscan equatorial mount with Go-To and tracking in both axes with access to 42,900+ objects in the Synscan handset's database.

The payload capacity for visual use is an impressive 23lbs in this configuration, so many options on telescope tube assemblies are open to the user.

For traveling, you can remove the DEC Axis from the mount together with the counterweight shaft and counterweights, reducing the instrument's weight considerably.

In this configuration, you can use a simple 44mm dovetail plate with standard 1/4 tripod screw (not supplied) and fit your camera directly using a ball head (not supplied).

With the DEC axis removed the mount only tracks in RA and you can easily take photos. 


  • Positioning Accuracy up to 1 arc minute. Accuracy enhanced by software collimation error (mount mechanical error) compensation.
  • High Precision Stepper Motors with 1.8° step angle and 64 micro steps driven.
  • Resolution 0.28125 Arc Second
  • Slewing speed up to 3.4°/sec (800X).
  • ST-4 type Autoguider Interface: Supports 0.25x, 0.5x, 0.75x 1x guiding rate
  • Dual or Single Axis Tracking
  • Tracking Rate: Lunar, Solar or Sidereal
  • Synscan™ Hand Controller with 42,900+ Object database containing complete Messier, NGC, and IC catalogs.
  • Periodic Error Correction.
  • PC compatibility.
  • Synscan Handset Firmware Upgradeable via internet download.
  • Supplied with WO Polarscope
  • Latitude Adjustment 15° to 65°
  • R.A. Worm Gear 92.5mm Diameter, 180 Teeth
  • DEC Worm Gear 34.3mm Diameter, 65 Teeth
  • R.A. Worm Drive 25.5mm Diameter, Steel
  • DEC Worm Drive 20mm Diameter, Steel
  • Payload Capacity 23Lbs 
  • Stabiliser Bar 20mm Diameter, Steel
  • Counterweights supplied: 2 x 3.4kg
  • Weight of Mount Head: 4.38kg (3.28 kg with DEC & Bar removed)
  • Reflex tripod, Weight:6.3kg, Reflex length:59cm
  • Power Requirement DC12V 3A Tip Positive
  • PoleMaster Adapter



Aperture103 mm (4")
Camera/Eyepiece Connection1.25" Nosepiece
Dawes Limit1.13 arcseconds
Focal Length710.7 mm
Focal Ratiof/6.9
Free ShippingYes
Glass TypeFPL53
Highest Magnification206x
Light Gathering Power217x
Limiting Magnitude13.8
Optical DesignDoublet
Tube Diameter112mm
Tube Length615mm
Tube Weight9.61 lbs


    Standard Package:
  • Mounting Rings
  • Guiding Rings
  • CNC Carry Handle Bar
  • Long Vixen Style Dovetail Plate
  • 2.5-inch Rack-and-Pinion Focuser
  • Innovative Bahtinov Mask Cover (Patented)
  • Two-year, no fuss warranty and constant customer service!