William Optics Zenithstar ZS81 WIFD ED Doublet Apochromatic Refractor Telescope
Introducing the WILLIAM OPTICS Internal Focus Design (WIFD) Apochromatic Series. This innovative and revolutionary design combines a precision (Patented) internal focusing mechanism with the highest quality optics available, providing the ultimate Apochromatic refractor for astrophotography. Designed from the ground up with the ability to handle the newest generation of large, heavy, high-resolution cooled cameras, the rock-solid optical tube assembly is uncompromised in quality. The movement of the focuser is integrated inside the main tube assembly, so there are no movements of a focuser drawtube visible from the outside. The user can enjoy the benefits of a traditional two speed fine focuser, while not worrying about limitations typically found in traditional rear mounted focusers.
Parts:
- A. Rear dust cap (M63)
- B. 120mm saddle handle bar
- C. WIFD focuser
- D. Dew shield locking screw
- E. Dew shield
- F. Lens cover with Bahtinov mask
- G. Front Bahtinov mask cover
- H. M6 screw holes for finder bracket
- I. Camera angle rotator
- J. 210mm Vixen-style dovetail
- K. 2-speed 10:1 ratio fine focus knob
- L. M4 screw holes for finder bracket
- M. Locking screws on saddle handle bar (M4)
- N. Camera angle rotation locking screw
- O. Mounting rings/knobs
- P. Focuser adjusting knob with thermometer
- Q. M92 to M63 adapter
Telescope Diagram:
R&P Gear Spacing Screws
Adjust the focuser ONLY when necessary by progressively pushing and pulling the screws until you reach the desired smoothness.
Note: Do not adjust without permission from ourselves or WO.
EAF Installation
NEW internal focuser.
Our new design includes the Patented WO centre focuser with precise internal sliding of fixed optics to prevent image shift. The integrated position viewing window on the focuser provides instant verification of the graduated numerical display. The smooth rack and pinion design is incorporated into the focuser to provide super fine adjustability for critical focus. The internal movement of the optical elements is protected from the elements and can’t come out of alignment. The redistribution of weight allows for better balance during imaging sessions.
The smooth rack and pinion design is incorporated into the focuser to provide super fine adjustability for critical focus. The user can enjoy the benefits of a traditional two speed fine focuser, while not worrying about limitations typically found in traditional rear mounted focusers. The redistribution of weight allows for better balance during imaging sessions. Compatible with ZWO EAF. Also new Electric Rotator will be available in near future.
DESIGN PRINCIPLE
Scaleable Design. The WIFD series will allow for many sizes and is not limited to smaller refractors. Additional optical designs are possible to meet various photographic requirements enhancing the line to include a number of apertures and fast focal ratios.
Inspired by the tremendous success of the WO CAT series of astrographs, William Optics has advanced the capabilities of astrophotography to the next level with this “no weight limit on photo accessories” design. The solid tube where accessories are attached, has a rigid design, and will not flex or exhibit any change in the optical path regardless of the weight of the camera and filter wheel attached to it.
CAT DESIGN
Improved “CAT” design ring tubes and dovetail base are lighter while remaining equally rigid. The new design allows for better balance with heavy accessories, and has integral placement of the focuser knobs, providing easy access to focusing during imaging. Included is the popular WO Saddle Bar Handle, critical for rigid guidescope mounting and autoguiding performance.
Super Smooth Field Rotator. Our field rotator design features smooth camera rotation with markings for degrees and a locking thumbscrew to prevent accidental camera movement, also new Electric Rotator will be available in near future.
Specifications: William Optics Zenithstar ZS81 WIFD
- Focal length: 559mm
- Aperture: 81mm
- Focal ratio: f/6.9
- Focuser: WIFD (WO Internal Focuser Design, compatible with EAF)
- Image circle: >Full frame
- Retracted length: 526mm
- Extended length: 607mm
- Dew shield circumference: 382mm
- Dew shield diameter: 121mm
- Weight: 7.82lbs / 3.545kg (OTA only), 10.05lbs / 4.560 (OTA with ring, dovetail and saddle)
NOTE: We are using a new lens cell design that includes FPL-53 glass in the WO two element designed APO refractor (Zenithstar series). This design is perfect for temperature compensation to better prevent pinched optics, that can occur in cold weather conditions Before storing your telescope, you must leave it uncovered, with the tube opened for enough time to allow it to adjust to the room temperature. You must make sure the telescope is completely dry of any dew or moisture before it can be safely stored. The telescope should always be stored in a dry location, with a consistent temperature.
At The Widescreen Centre, we prioritize prompt order processing and dispatch. We strive to dispatch all orders on the same day or the next working day, depending on the time of your order. We hold extensive stocks to ensure that your items are ready for immediate despatch. Please note that the cut-off time for same-day dispatch is usually 1:30 p.m.
For delivery within Mainland UK, we use reputable couriers to provide efficient service. You can expect your package to arrive in 1-2 working days. Please note that a signature may be required upon delivery to ensure a secure receipt.
In the case of special order items, the delivery time may be longer. If you have any concerns or questions about the delivery of your item, please don't hesitate to Contact Us. We are here to assist you.
Should there be any delay in dispatching your order, we will notify you to keep you informed.
Please be aware that The Widescreen Centre cannot be held responsible for any postal or third-party delays that may occur. We are committed to providing a reliable and efficient delivery service for our valued customers.
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