William Optics ZenithStar 81 WIFD
William Optics
William Optics ZenithStar 81 WIFD is an 81 mm Doublet APO refractor for wide-to-mid-field nebulae and general deep-sky imaging.
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Specifications
Optics
- Optical design
- Doublet APO refractor
- Aperture
- 81 mm
- Focal length
- 559 mm
- Focal ratio
- f/6.9
- Dawes limit
- 1.43"
- Glass / elements
- Doublet APO prime lens
Imaging
- Image circle
- 45 mm
- Camera format
- Full frame / APS-C / Micro 4/3
- Full-frame coverage
- Yes
- Back focus
- Depends on selected William Optics flattener/reducer
- Reducer / flattener
- Optional FLAT6AIII 0.8× reducer / flattener
Mechanical
- Focuser
- WIFD rack-and-pinion internal focuser
- Weight
- 3.55 kg / 7.82 lb
- Tube length
- 526-607 mm
- Dovetail
- Vixen-style dovetail
Astrophotography Fit
Best for wide-to-mid-field nebulae and general deep-sky imaging when the mount, camera format, and correction hardware are chosen as one system.
William Optics ZenithStar 81 WIFD sits in the telescope slot for wide-to-mid-field nebulae and general deep-sky imaging. The useful headline specs are aperture 81 mm, focal length 559 mm, f/6.9.
Camera coverage: Full frame / APS-C / Micro 4/3. Image circle: 45 mm. Back focus: Depends on selected William Optics flattener/reducer.
Refractors keep the field routine calmer: no regular collimation, predictable cooldown, and a clean path to autofocus and filtered imaging. The tradeoff is aperture and reach.
Weight matters here: 3.55 kg / 7.82 lb. Leave payload headroom for the camera, guider, focuser, dew control, and cables instead of judging the mount by bare tube weight alone.
Best paired with
- Corrected field flattener or reducer when the design requires one
- Cooled APS-C or smaller astro cameras matched to the image circle
- Autofocus, guide scope or OAG, and a mount with comfortable payload margin
Not recommended for
- Large full-frame sensors unless the corrected field supports them
- Very small travel mounts near their realistic imaging payload limit
- Buyers expecting one telescope to be ideal for every target size
Where To Buy
Some links on this page are affiliate links. Prices and availability are pulled automatically from each retailer and updated daily.
| Retailer | Price | Availability | View Offer |
|---|---|---|---|
| Cloud Break Optics Cloud Break Optics | $1,098.00 | In stock Updated 5/11/2026 | View Offer - $1,098.00 |
| High Point Scientific High Point Scientific | $1,098.00 | In stock Updated 5/12/2026 | View Offer - $1,098.00 |