Astronomy Specialist



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The William Optics ZenithStar 61 II is a two element apochromatic refractor with a focal ratio of f/5.9 and a focal length of 360mm. Utilizing FPL-53 synthetic fluorite glass, this telescope provides excellent aberration correction.

The 2" 10:1 rack & pinion focuser is smooth, stable and reliable, providing no slippage over long imaging sessions. The new CNC-machined and anodized Cat handle bar with finder-style saddle is perfect for attaching a guide scope or other accessories. The ZenithStar 61 II also includes William Optics' innovative clear Bahtinov mask integrated into the lens cap.

For best imaging results, it is recommended to pair the ZenithStar 61 II with its matching Flat61A field flattener or the Flat61R 0.8x reducer.


William Optics ZenithStar 61 test report


Optical design

Apochromatic doublet

Objective diameter

61 mm

Focal length

360 mm

Focal ratio


Image circle

43 mm (with Flat61A field flattener)

Compatible flattener

William Optics Flat61A, Flat61R

Mount attachment

210 mm Vixen-style/Arca-Swiss dovetail bar


Rack & pinion dual speed (10:1) 2" diameter

Camera connection

M54 x 0.75, 2"


67.9 mm (with flattener/reducer)

Tube weight

2.2 kg (including accessories)

Tube length

245 mm (fully retracted), 315 mm (fully extended)

Tube diameter

75 mm

Dew shield diameter

80 mm


WO-A-Z61IIGD (Gold), WO-A-Z61IIRD (Red)


William Optics ZenithStar 61 backfocus


  • ZenithStar 61 II
  • Lens cap with Bahtinov mask
  • CAT finder saddle handle bar
  • 210 mm Vixen-style dovetail bar
  • M54 to 2" adapter
  • 2" to 1.25" adapter
  • Soft carry case

Customer Reviews

Based on 2 reviews
John Holgate

An excellent all-round scope. I wanted something that could handle astro & wildlife photography, finder scope, guide scope and occasional spotter scope duties and the Z61 fits the bill. But - you really do need the flattener. Without it, the Z61 has a lot of field curvature, particularly for an APSC DSLR or bigger. Without the flattener, my DSLR photos were only sharp from the center to halfway across the photo. Add the flattener and we're sharp to the edge. No chromatic abberation to speak of - even sunlit reflections only show a pure white reflection - much better than the ED72 or ED80. Contrast and sharpness are excellent. Built quality is top notch - everything is smooth and consistent. One mildly annoying design aspect is that the focus knobs don't quite clear the mounting foot - so every time I take it in and out of it's case, I have to release the scope from the ring, turn and replace so it fits back into it's padded bag. (If you're not worried about your focus knobs being parallel to the ground, this won't be an issue). Focus travel is smooth, consistent and generous at around 70mm. Focus with the flat 6A at infinity is around halfway through the travel - so plenty of scope (pun intended) for close-ish photography. While the focus unit does not turn, the flattener does have the ability to spin so you can adjust the camera's angle easily. Also makes for a nice sharp finder scope - although the field curvature does make it's presence felt. I am looking forward to lots of photography through this very nice bit of kit.

Pat Harrington
great scope

better than I thought. Great quality scope and light. Great grab and go scope.

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