William Optics ZenithStar 61II
William Optics
William Optics ZenithStar 61II is a 61 mm Doublet APO refractor for wide-to-mid-field nebulae and general deep-sky imaging.
Best Current Offer
Specifications
Optics
- Optical design
- Doublet APO refractor
- Aperture
- 61 mm
- Focal length
- 360 mm
- Focal ratio
- f/5.9
- Dawes limit
- 1.9"
- Glass / elements
- Doublet APO objective
Imaging
- Image circle
- 42 mm
- Camera format
- APS-C / Micro 4/3 with corrector
- Full-frame coverage
- No
- Back focus
- Depends on selected William Optics flattener/reducer
- Reducer / flattener
- Optional Flat61A / Flat61R reducer-flattener options
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 61II sits in the telescope slot for wide-to-mid-field nebulae and general deep-sky imaging. The useful headline specs are aperture 61 mm, focal length 360 mm, f/5.9.
Camera coverage: APS-C / Micro 4/3 with corrector. Image circle: 42 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.
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
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| Retailer | Price | Availability | View Offer |
|---|---|---|---|
| Cloud Break Optics Cloud Break Optics | $599.00 | In stock Updated 5/11/2026 | View Offer - $599.00 |