William Optics WIFD GT81 81mm f/5.9 Apo Refractor Astrophotography Package - Space Gray
Ships by Next Business Day
Contiguous US Customers:
All items we sell ship for free within the Contiguous US. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. During checkout, you may also be shown other optional faster shipping choices.
US Customers in Hawaii and Alaska:
Free shipping applies to almost all products. A few large telescopes and mounts are excluded from this free shipping offer. For these items, please contact us to obtain a shipping quote before you check out using the online shopping cart.
International Customers:
Free shipping does not apply to international orders. During check-out, you will be presented with several shipping choices and costs. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions.
Introducing the first telescope in the William Optics Internal Focus Design (WIFD) Apochromatic Series: The WIFD Gran Turismo 81mm APO Refractor.
- 81mm f/5.9 triplet APO refractor telescope with WIFD
- Astrophotography package that includes a 0.8x reducer/flattener and 32mm guide scope
- Revolutionary new internal focuser design prevents sensor tilt and focuser slippage
- Temperature compensated lens design
- Also available as a standalone telescope
William Optics WIFD GT81 Review
Astrophotographer and Agena Affiliate Bray Falls recently created this William Optics WIFD GT81 review video:
William Optics WIFD GT81 Astrophotography Package
This special astrophotography package includes the following extra items:
- William Optics Flat6AIII 0.8x Reducer/Flattener
- The Flat6AIII is a tried and tested reducer/flattener that features an image circle of 44mm and was designed with full frame sensors in mind. It will reduce the GT81 from a 478mm focal length f/5.9 to a 382mm f/4.7 telescope for a 50% increase in light gathering ability.
- William Optics 32mm f/3.75 UniGuide Scope with Slide-Base - Red
- The 32mm f/3.75 UniGuide Guide Scope is a an excellent choice for autoguiding and will easily attach to the GT81's built in guide scope rail. Just add a guide camera, and you're ready to go.
Overview of the William Optics Internal Focus Design (WIFD)
If you are an astrophotographer, you've likely looked into upgrading your telescope's focuser at some point. The stock focusers on many telescopes are simply not capable of supporting the weight of today's heavy image trains that can include a rotator, off-axis guider, filter wheel, camera, and more. This can cause the focuser to slip out of focus, or even worse: cause dreaded sensor tilt, which can be daunting to fix.
The innovative team at William Optics has been hard at work trying to resolve this problem, and have now announced their patented solution: the William Optics Internal Focus Design, or WIFD for short.
The WIFD is a revolutionary telescope design that moves the focuser from the rear exterior of the telescope to the inside. The WIFD focuser drawtube stays housed in the main chassis of the telescope, which results in a dramatically more stable focuser:
The WIFD features a smooth rack and pinion design that is incorporated into the focuser to provide precise adjustability for critical focus. The internal movement of the optical elements is protected from the elements and can't come out of alignment. This redistribution of weight allows for better balance during imaging sessions.
New Temperature Compensated Lens Cell Design
Super Smooth Field Rotator
The included field rotator features smooth camera rotation with markings for degrees and a locking thumbscrew to prevent accidental camera movement.
Scalability of the William Optics Internal Focuser Design
The WIFD will not just be limited to the GT81, and will be adapted to many sizes of refractors. Additional optical designs are possible to meet various photographic requirements enhancing the line to include a number of apertures and fast focal ratios.
Please note: The focuser travel does not extend over the full range of the markings shown on the telescope tube. This is normal in all WO WIFD/Pleiades telescopes and not a defect in your particular unit.
William Optics WIFD GT81 Specifications
- Lens Type: Triplet Apochromatic Prime Lens
- Focal Length: 478mm
- Diameter: 81mm
- F/ Ratio: f/5.9
- Compatible Reducers & Flatteners: FLAT6AIII 0.8x Reducer/Flattener (included) | FLAT68III 1.0x Field Flattener (not included; also requires additional # AD-M80-45-M48 adapter)
- Focuser: WIFD, Compatible with EAF
- Back focus specifications:
- Telescope only: Available maximum backfocus is 183.4mm from the base of the M63 male thread. Telescope can focus as long as your image sensor is placed anywhere between the scope and 183.4mm.
- Telescope with P-FLAT6AIII flattener (included): 55mm with flattener adjustment scale set to 7.1mm
- Telescope with P-FLAT68III flattener (sold separately and requires use of an additional adapter): 55mm with flattener adjustment scale set to 10.9mm
- Image circle size (OTA only, OTA with FLAT6AIII, OTA with FLAT68III): All 44.4mm (full frame coverage)
- OTA weight: 7.3 lbs (3.3 kg)
- Total weight (with rings & dovetail plate): 9.9 lbs (4.5 kgs)
- Tube length (dew shield fully retracted): 420mm
- Tube length (dew shield fully expanded): 500mm
- Dew shield OD: 121mm / 4.76"
- Color: Space Gray
- Lens Glass Type: FPL-53
- Strehl Ratio: 0.95+
- Camera Format: Full Frame | DSLR | Mirrorless | CMOS | CCD
- Zygo Test Report: Included
- M48 T-Mounts Supported: Canon EF, RF | Nikon F, Z | Sony E | Pentax K | Micro Four Thirds (M4/3) | FUJI X
| Free Shipping Graphic | Free Contiguous US Shipping |
|---|---|
| Telescope Focal Length | 401 - 500mm |
| Hide Found a better Shipped Price on Frontend? | No |
- William Optics WIFD GT81 81mm f/5.9 Apo Refractor OTA - Space Gray
- William Optics Flat6AIII 0.8x Reducer/Flattener
- William Optics 32mm f/3.75 UniGuide Scope with Slide-Base - Space Gray
- Lens cover with Bahtinov Mask
- Zygo Test Report
- Soft Case
Introducing the first telescope in the William Optics Internal Focus Design (WIFD) Apochromatic Series: The WIFD Gran Turismo 81mm APO Refractor.
- 81mm f/5.9 triplet APO refractor telescope with WIFD
- Astrophotography package that includes a 0.8x reducer/flattener and 32mm guide scope
- Revolutionary new internal focuser design prevents sensor tilt and focuser slippage
- Temperature compensated lens design
- Also available as a standalone telescope
William Optics WIFD GT81 Review
Astrophotographer and Agena Affiliate Bray Falls recently created this William Optics WIFD GT81 review video:
William Optics WIFD GT81 Astrophotography Package
This special astrophotography package includes the following extra items:
- William Optics Flat6AIII 0.8x Reducer/Flattener
- The Flat6AIII is a tried and tested reducer/flattener that features an image circle of 44mm and was designed with full frame sensors in mind. It will reduce the GT81 from a 478mm focal length f/5.9 to a 382mm f/4.7 telescope for a 50% increase in light gathering ability.
- William Optics 32mm f/3.75 UniGuide Scope with Slide-Base - Red
- The 32mm f/3.75 UniGuide Guide Scope is a an excellent choice for autoguiding and will easily attach to the GT81's built in guide scope rail. Just add a guide camera, and you're ready to go.
Overview of the William Optics Internal Focus Design (WIFD)
If you are an astrophotographer, you've likely looked into upgrading your telescope's focuser at some point. The stock focusers on many telescopes are simply not capable of supporting the weight of today's heavy image trains that can include a rotator, off-axis guider, filter wheel, camera, and more. This can cause the focuser to slip out of focus, or even worse: cause dreaded sensor tilt, which can be daunting to fix.
The innovative team at William Optics has been hard at work trying to resolve this problem, and have now announced their patented solution: the William Optics Internal Focus Design, or WIFD for short.
The WIFD is a revolutionary telescope design that moves the focuser from the rear exterior of the telescope to the inside. The WIFD focuser drawtube stays housed in the main chassis of the telescope, which results in a dramatically more stable focuser:
The WIFD features a smooth rack and pinion design that is incorporated into the focuser to provide precise adjustability for critical focus. The internal movement of the optical elements is protected from the elements and can't come out of alignment. This redistribution of weight allows for better balance during imaging sessions.
New Temperature Compensated Lens Cell Design
Super Smooth Field Rotator
The included field rotator features smooth camera rotation with markings for degrees and a locking thumbscrew to prevent accidental camera movement.
Scalability of the William Optics Internal Focuser Design
The WIFD will not just be limited to the GT81, and will be adapted to many sizes of refractors. Additional optical designs are possible to meet various photographic requirements enhancing the line to include a number of apertures and fast focal ratios.
Please note: The focuser travel does not extend over the full range of the markings shown on the telescope tube. This is normal in all WO WIFD/Pleiades telescopes and not a defect in your particular unit.
William Optics WIFD GT81 Specifications
- Lens Type: Triplet Apochromatic Prime Lens
- Focal Length: 478mm
- Diameter: 81mm
- F/ Ratio: f/5.9
- Compatible Reducers & Flatteners: FLAT6AIII 0.8x Reducer/Flattener (included) | FLAT68III 1.0x Field Flattener (not included; also requires additional # AD-M80-45-M48 adapter)
- Focuser: WIFD, Compatible with EAF
- Back focus specifications:
- Telescope only: Available maximum backfocus is 183.4mm from the base of the M63 male thread. Telescope can focus as long as your image sensor is placed anywhere between the scope and 183.4mm.
- Telescope with P-FLAT6AIII flattener (included): 55mm with flattener adjustment scale set to 7.1mm
- Telescope with P-FLAT68III flattener (sold separately and requires use of an additional adapter): 55mm with flattener adjustment scale set to 10.9mm
- Image circle size (OTA only, OTA with FLAT6AIII, OTA with FLAT68III): All 44.4mm (full frame coverage)
- OTA weight: 7.3 lbs (3.3 kg)
- Total weight (with rings & dovetail plate): 9.9 lbs (4.5 kgs)
- Tube length (dew shield fully retracted): 420mm
- Tube length (dew shield fully expanded): 500mm
- Dew shield OD: 121mm / 4.76"
- Color: Space Gray
- Lens Glass Type: FPL-53
- Strehl Ratio: 0.95+
- Camera Format: Full Frame | DSLR | Mirrorless | CMOS | CCD
- Zygo Test Report: Included
- M48 T-Mounts Supported: Canon EF, RF | Nikon F, Z | Sony E | Pentax K | Micro Four Thirds (M4/3) | FUJI X
| Free Shipping Graphic | Free Contiguous US Shipping |
|---|---|
| Telescope Focal Length | 401 - 500mm |
| Hide Found a better Shipped Price on Frontend? | No |
- William Optics WIFD GT81 81mm f/5.9 Apo Refractor OTA - Space Gray
- William Optics Flat6AIII 0.8x Reducer/Flattener
- William Optics 32mm f/3.75 UniGuide Scope with Slide-Base - Space Gray
- Lens cover with Bahtinov Mask
- Zygo Test Report
- Soft Case
William Optics WIFD GT81 81mm f/5.9 Apo Refractor Astrophotography Package - Space Gray # T-GT-81SG-WIFD-AP