William Optics ZenithStar 81 APO Doublet Refractor with WIFD - Gold
An Improved APO Doublet Refractor from William Optics!
The ZenithStar 81 APO WIFD is a choice refractor for both beginners and seasoned astrophotographers. Building on the proven performance of its predecessor, the ZenithStar 81 APO now features the William Optics signature Internal Focus Design (WIFD). Finished in an elegant gold, this doublet refractor will deliver exceptional performance for both visual astronomers and astrophotographers!
The ZenithStar 81 APO WIFD is a premium refractor that offers advanced optical precision and versatile imaging performance. The 2-element "doublet" design gives this scope a compact and lightweight build, and the durable CNC machined components feature a smooth gold finish. To make this scope resistant to optical distortion, such as “pinching”, William Optics engineered the ZenithStar with a unique lens cell construction that utilizes super low dispersion FPL-53 glass. The ZenithStar 81 APO WIFD also features a 10:1 precision internal focuser that maintains consistent alignment even under heavy loads. The focuser design also improves balance and can be integrated with the latest EAFs. For those who wish to further enhance this scope’s capabilities, you’ll find plenty of optional accessories, like the Flat6AIII and the 50mm Uniguider. With the glamorous gold finish, innovative improvements, and compact construction, this doublet refractor will certainly be a standout, stylish addition to your astro-imaging toolkit!
Advanced Design & Consistent Performance
Across its entire 559 mm of focal length, the ZenithStar 81 APO WIFD proves to be a dependable doublet! With its numerous enhancements and accessories, such as the refined internal focuser and unique lens cell construction, this thoughtfully crafted scope consistently delivers outstanding results! For deep dive into this scope’s impressive build and accessories, check out the key features below!
Opulent Optics
With a tried and true 2-element design, the ZenithStar 81 APO WIFD delivers dependable and consistent optical performance. At the heart of this scope lies two FLP-53 glass elements, providing remarkable color correction. With an 81 mm aperture and a 559 mm focal length, this scope supplies a focal ratio of f/6.9, which can be dialed back to f/5.5 with the Flat6AIII reducer and flattener. This optional accessory is crafted using Ohara glass and is fully multi-coated, ensuring it will produce crystal-clear views and beautiful flat field across the 97% of the 45mm image circle.
Please Note:To ensure the safety and longevity of the optics, William Optics recommends thoroughly drying the telescope to remove any moisture or dew, allowing it to slowly acclimate to room temperature, and then storing it in a dry space with a consistent temperature.
Signature Internal Focuser
The previous ZenithStar 81 APO utilized a rear mounted focus design, which had the possibility to cause misaligned optics when using heavier equipment. Understanding this concern, William Optics reworked the beloved ZenithStar series to include their signature internal focusing design. This innovative improvement relies on an internal focus mechanics, which allows the second element to move while any attached equipment remains fixed to the OTA. Beyond the performance refinements, the WIFD design further improves balance and eliminates vignetting of traditional focuser designs, all while maintaining the versatility of the 2 speed 10:1 Rack & Pinion focuser, which can be easily integrated with the latest EAFs, like the ZWO 5v EAF!
Included and Optional Accessories
When you purchase the ZenithStar 81 APO WIFD, you don’t just receive an outstanding doublet OTA. You’ll also receive numerous streamlined accessories and a soft padded carry case! Starting from the top, you’ll find a dual-use M121 dust cover/Bahtinov mask and a fully integrated, retractable dew shield. There are also two tube rings with a 210 mm Vixen-style dovetail plate below and a 120 mm saddle handlebar atop, perfect for mounting the optional 50mm (Gold) Uniguider. Additionally, you get an M92 threaded camera rotator with a fine-grained angle gauge for easy return, and an M92 – M63 adapter that can be used to attach the optional Flat6aIII reducer and flattener. Closing it off, you’ll find a CNC machined M62 dust cap, finished in the same elegant gold as the OTA and other included accessories. All this is easily stored in the signature William Optics soft padded carry case, along with any number of optional accessories!
Reliable and Ready-to-go!
The ZenithStar 81 APO WIFD is a powerful scope with a compact build, making it great for astrophotographers on the move! The OTA is just under 24" (607mm) when fully extended, and just over 20" (526 mm) when the retractable dew shield is withdrawn. The OTA only weighs 7 lb (3.54 kg) without the included accessories and a bit over 10 lb (4.56 kg) when fully loaded, making this scope a suitable match for any number of mounts, such as the ZWO AM5n! With the dual use saddle handlebar and included soft-padded carry case, this durable, yet lightweight scope ready-to-go wherever your next adventure takes you!