We are very exciting to announce All New 2019 Super ZenithStar 81 F6.9 imaging APO!!!
Innovative Bahtinov Mask Cover (Patented) included!
This beautiful scope is everything you always wanted in a refractor, starting from extreme sharpness for clear details, and APO color correction.
It has all the benefits of the ZenithStar family at a price that is truly unbelievable.
William Optics ZS81 Features
F/6.9 FPL53 Doublet air-spaced APO, in CNC machined ultra-high precision lens cell;
F5.5 with x0.8 Flattener.
2.5”R&P Ultra robust focuser with 1:10 dual speed: a treat to use during astrophotography. No image shifting! Heavy duty: perfect for your accessories.
An in house Zygo interferometer test & report is available with this telescope. Click here to read about the interferometer test in more detail. There are various packages available on this model. Please select from the packages above. The optical test and enhance includes a full inspection of the telescope, including optics, focuser, paintwork and other mechanical parts. A precise optical check is then performed then the scope is enhanced to ensure you get the best possible optical performance from your new instrument.
The interferometer is essentially a measuring instrument. Within the interferometer is a calibrated laser that is pointed through the optical test surface, then onto a high quality reference sphere, then back through the test subject then to an internal camera which gives us the measurement on the screen. From this, we can adjust the position of the test optic and the reference sphere to obtain a perfectly calibrated system. The more central the laser to the test optic and then on return, the better and more accurate reading and measurement we can take. This takes a lot of adjustment to get the best results from the optical surface. Once the measurement has been taken, we are provided with a series of results that show the optical quality of the surface plus other information. We will aim to provide 0.95 Strehl or higher. 
Do-all instrument
Despite its 81mm 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 possible with proper additional equipment.
Standard Package：
• Mounting Rings
• New 2019 CNC Carry Handle Bar
• New DuelSide Dovetail plate (DSD 210)
• 2.5” R&P Focuser
• Innovative Bahtinov Mask Cover (Patented)
• Two-year, no fuss warranty and constant customer service!
Retracted Length：456mm
Tube with Rings and Dovetail Weight：3.50kg
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