William Optics Gran Turismo 81 APO Refractor Kitw Internal Focus Design and 32mm UniGuide - Red
| Article number: | WO-GT81-IFD |
| Availability: | In stock |
| Delivery time: | In Stock! |
THE NEW GAMECHANGER!
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.
FOCUSER DESIGN
NEW internal focuser. Our new design includes the Patented WO center 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.
DESIGN PRINCIPLE
Scalable 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.
ZYGO TEST REPORT
GRAN TURISMO 81 WIFD Technical Specification
- Lens Type
- Triplet Apochromatic Prime Lens
- Focal Length
- 478mm
- Diameter
- 81mm
- F/ Ratio
- f/5.9
- Optional Flattener
- FLAT6AIII 0.8x
- FLAT68III 1.0X (Require WIFD Extension Adapter)
- Focuser
- WIFD
- Compatible with EAF
- Color
- Red
- Lens Material
- FPL-53
- Strehl Ratio
- 0.95+
- Camera Format
- Full Frame
- DSLR
- Mirrorless
- CMOS
- CCD
- Test Report
- Included
- T-Mounts Supported
- Canon EF, RF
- Nikon F, Z
- Sony E
- Pentax K
- Micro Four Thirds (M4/3)
- FUJI X
- OTA Weight
- 7.3 lbs (3.3 kg)
- Total Weight
- 9.9 lbs (4.5 kgs)
- Tube Length (Retracted)
- 420mm
- Tube Length (Extended)
- 500mm
The William Optics Gran Turismo 81 is an apochromatic triplet refractor with a unique focuser design.
Unlike other focusers, the mechanism is internal to the tube of the scope, making it much more stable when cameras and other accessories are attached. This design also virtually eliminates vignetting!
The Gran Turismo 81 provides 81 mm of aperture. The optical configuration is a triplet design. The apochromatic glass is FPL-53. All of this combines to produce crisp, clean, high contrast, and sharp images without chromatic aberration. The focal length of the system is 478 mm, yielding a focal ratio of f/5.9.
In addition to the Gran Turismo 81, this package also includes the William Optics Flat6AIII field flattener/reducer which provides 0.8x reduction, as well as the William Optics 32 mm UniGuide Finder Scope with a focal length of 120 mm and a focal ratio of f/3.75, which mounts onto the handle of the GT81.
A Technically Capable and Stylish Astrograph
In addition to the patented "William Optics Internal Focus Design" focuser, many high quality components and accessories are included. The red highlights provide a stylistic flourish to the scope. The triplet refractor design provides high quality optics in a triplet configuration. The included Bahtinov mask aids in achieving focus. The versatile tube rings with handle provides an easy way to carry the tube, as well as doubles as a shoe for the mounting of small accessories, such as a finder scope. In all, the William Optics Gran Turismo 81 is stylish, capable, and innovative astrograph!
Introducing the William Optics Internal Focus Design (WIFD)
This new focuser design includes the patented William Optics center 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 cannot come out of alignment. The redistribution of weight allows for better balance during imaging sessions.
Outstanding Optics
The Gran Turismo 81 features excellent optics to get the most out of your images. The optical assembly of this refractor is in a triplet configuration, made of FPL-53 apochromatic glass to reduce chromatic aberration and provide excellent contrast, color correction, and sharpness. As mentioned in more detail above, the unique internal focuser design slides otherwise fixed optics to prevent image shift and virtually eliminate vignetting.
Included Reducer/Flattener
The included William Optics 2" Field Flattener/Reducer has been designed to optimize the flat-field imaging performance of the GT81. The APO triplet optics of the Flat6AIII are made with Ohara glass and fully multi-coated to provide good illumination and a beautifully flat field across 97% of full frame sensors. The reducing factor is 0.8X. Designed with M63 threads on the telescope side, this flattener/reducer threads directly into the telescope. The Flat6AIII has 2" threads on the opposite side to accept a 48 mm (Wide) T-ring for your DSLR. There is even a slot behind the 2" threads to accept an M48 filter.
Included Slide-Base 32 mm UniGuide Finder Scope
The included 32 mm UniGuide guide scope has a focal length of 120 mm and a focal ratio of f/3.75 and mounts into the handle of the Gran Turismo 81. The back of the UniGuide comes with an M42 thread for attaching 1.25" cylindrical-type guide cameras such as those by QHY, SBIG, and ZWO. Tightening knobs will ensure a stable fit for the attached guiding equipment.
Additional Accessories
The William Optics Gran Turismo 81 WIFD comes with several accessories to improve performance and convenience. In addition to the included flattener/reducer, UniGuide finder scope, and internal focusing mechanism, the GT 81 includes a Rotolock field rotator which allows for precise and convenient orientation of a connected camera. The Bahtinov mask aids in focusing. The optical tube rings and dovetail allow for easy mounting. The included handle doubles as a shoe for attaching small accessories, such as a finder scope. Lastly, a soft carrying case is included to make transportation a breeze!