FREE DELIVERY TODAY - 10% Discount for next 3 orders! Place your 1st order in.
Until the end of the sale:
00
days
00
hours
00
minutes
00
sec.
Hot DealsSALE
Soon stocks will run out
Dont miss this opportunity while supplies last.
William Optics ZenithStar 81 AP 81/559 Gold OTA Specs
| Brand | William Optics |
| Full Model Code | William Optics ZenithStar 81 Extra-Low Dispersion Apochromatic Refractor Optical Tube Assembly - Gold Edition |
| Country of Origin | Taiwan (Design, Precision Engineering, Structural Fabrication, and Optical Assembly) |
| Optical Design | Apochromatic Refractor (2-Element Air-Spaced Doublet Lens Layout with internal baffling rings) |
| Aperture | 81 mm (3.19 inches) |
| Focal Length | 559 mm |
| Focal Ratio | f/6.90 |
| Optical Coatings | Ultra-Pure Multi-Layer Anti-Reflective coatings (STM Coating) applied across all structural air-to-glass lens borders |
| Glass Material | Premium FPL-53 Synthetic Fluorite Extra-Low Dispersion (ED) Japanese Glass substrate for advanced chromatic balance |
| Secondary Mirror Obstruction | 0 mm (Unobstructed Optical Path Setup) |
| Secondary Mirror Obstruction by Diameter | 0% |
| Secondary Mirror Obstruction by Area | 0% |
| Resolving Power | 1.43 Arcseconds (Dawes), 1.71 Arcseconds (Rayleigh) |
| Limiting Visual Magnitude | 11.3 |
| Highest Useful Magnification | 162x |
| Lowest Useful Magnification | 12x |
| Optical Tube Material | CNC-Machined High-Grade Aluminum Alloy Tube Body finished in powder-white with premium hard-anodized gold accent panels |
| Focuser Style & Mechanism | 2.5-inch Heavy-Duty Rack and Pinion Focuser featuring a 10:1 dual-speed micro-adjustment drive wheel |
| Mirror Lock Mechanism | No (Fixed structural lens elements prevent manual cell shifting or focus mechanics tilt) |
| Optical Tube Dimensions | 93 mm x 456 mm (Tube Outer Diameter x Minimum Collapsed Structural Length with retracted dew shield) |
| Optical Tube Weight | 3.53 kg (7.78 lbs) (Total weight rating inclusive of standard dual CNC tube rings and Vixen-style dovetail bar assembly) |
| Mount Attachment Type | Dual CNC Mounting Rings linked to a standard combined Vixen-style and Arca-Swiss compatible Dovetail Mounting Plate |
| Finder Scope Specification | Integrated Patented Bahtinov Focus Mask configured inside the structural aluminum slide-out dew shield cap assembly |
| Included Accessories | 81mm SD Doublet Optical Tube, Dual CNC Tube Rings, Saddle Handle Bar, Arca-Swiss/Vixen Dovetail Rail, Integrated Bahtinov Mask Cap |
| Standard Warranty | 2-Year Limited Warranty |
| Application | Mid-range wide-field astrophotography and crisp lunar detailing, blending a generous 3.1-inch aperture profile with low-maintenance structural doublet ergonomics. |
Reviews
There are no reviews yet.