KIT TO ADD
flat frames.
We also noted that optical distortion was present towards the edge of frame. It was by no means terrible, but it would get in the way of serious astrophotography. This can be addressed using an optional field-flattener, such as the William Optics Flat 61A which is designed for use with this scope – although this will set you back an extra £170. At the time of the review the flattener wasn’t available.
As a reworked model of the ZS61, the ZS61-II also offers many thoughtful touches, including the Bahtinov focus-assist mask mentioned earlier, an extendable dew shield and the dual-speed rack and pinion focuser. What’s new is the mounting cradle, which has a mounting point for an optional guidescope. We tested the William Optics UniGuide guidescope with a 50mm aperture and a 200mm focal length, an optical specification that’s not far from the ZS61-II itself. Of course, the UniGuide’s optics aren’t as refined, nor are its focuser or eyepiece holder.
The UniGuide costs a further £125, but it’s worth it if you’re serious about auto-guided long-exposure imaging. It’s designed to accept a modern, small format guide camera, such as those produced by QHY, ZWO and Altair, with the camera fitting into a 1.25-inch Rotolock adaptor – a 1.25-inch focuser that uses an external rotary screw collar for locking the camera in place. Focusing is achieved by adjusting the front section of the UniGuide and locking it with a ring. The UniGuide is fast at f/4 and delivers a big, wide field of view. Typically, this means you should have a good number of guide stars to choose from.
In summary, the ZS61-II is an attractive scope for wide-field viewing and astrophotography. It’s highly portable and feels as if it would survive a bump or two, plus it’s easy to use and doesn’t compromise on functionality. It would also make a high-quality guidescope for a larger instrument.
William Optics adjustable field flattener for Zenithstar 61
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William Optics Copper M48 T mount for Canon EOS / Nikon cameras
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ZWO ASI120MM Mini Monochrome USB 2.0 Camera
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A high frame-rate capture of the Moon, taken with a ZWO ASI174MM camera attached to the ZS61-II. The image is small but highly detailed ▼ The field of view through the UniGuide guidescope, using a ZWO ASI174MM camera for guiding