REVIEW: William Optics 32mm Slide-base Uniguide Scope
First published November 2021
Last updated January 2026
Intro
Guiding is an important part of astroimaging, ranking highly in my own list of the most useful upgrades for astrophotography. By improving a mount’s tracking accuracy, guiding allows you to follow targets precisely across the night sky and enables dithering, which is widely considered essential for clean, high quality results. One way to achieve this is with a guidescope and guide camera. For several years I used the William Optics 32mm slide base Uniguide Scope, reviewed here, and found it to be an excellent and surprisingly affordable option at just £99.
Vital statistics
First off, the vital statistics. It has a lens diameter of 32mm, an aperture of f3.75, and a focal length of 120mm. Its overall weight is just 240g. I like small and light accessories, so we’re off to a good start! From the specifications alone we can see that it’s well-suited to wide-field astrophotography and portable set-ups. It’s even available in a few different colours; I bought a red version, which matches well with the livery of my Askar FRA400 astrograph and ZWO-branded accessories.
A guidescope such as this needs a guidecam to function. Fortunately, attaching one quite easy. An M42 thread is provided, and if your guidecam has a cylindrical 1.25” connection then just pop it in the back and tighten the three metal thumbscrews. Some adjustment may be needed to get the correct backfocus (20.1mm), but this doesn’t take too long. I use my William Optics 32mm Slide-base Uniguide Scope with a ZWO ASI 120MM Mini, which is a perfect match.
Focussing
Focussing is achieved by twisting the dew shield until an image is sharp, and then tightening a locking ring. It’s a fairly simple operation, and the locking ring mechanism means that focus will be held with no slippage. I focussed my William Optics 32mm Slide-base Uniguide Scope almost a year ago, and have never needed to adjust it.
Image quality is a-ok, with sharp stars across the image. The wide field of view is useful for finding a multiple guide stars, a boon given that my ASIAIR Plus now uses multi-star guiding as standard.
Slide-base
The “slide-base” mentioned in the name is a built-in Vixen-style base. This is designed for attaching to the saddle handle bar used with many Williams Optics telescopes, but importantly for me it’s also compatible with traditional finderscope brackets too. The slide-base provides a rock-solid foundation for the guidescope, and also allows it to be mounted close to a telescope’s optical tube assembly. This reduces flex and makes balancing an imaging rig a little easier.
If you’ve got a long focal length imaging system then this guidescope probably won’t cut it, and you may want to go down the route of an off-axis guider instead.
Summary
In summary: if you have a wide-field or portable imaging rig and need a guidescope, the William Optics 32mm Slide-base Uniguide Scope will do you proud.
Where to buy
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William Optics 32mm Slide-base Uniguide Scope
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ZWO ASI 120MM Mini
Read my review
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I’m surprised that the stars are good across the image for you, the corners of mine are terrible as if it needs more backfocus but after measuring/ not really having much more room to achieve more backfocus I haven’t had any luck there (yes I have the extension on the ZWO cam). Wondering if my copy is just a bad copy, was looking into the 50mm but I image pretty widefield. Just checked your review out of curiosity and was surprised to see that about your stars.
I had no complaints with mine, the quality was fine across the field. Maybe you do just have a bad copy, but you’d hope that William Optics would be tight on quality control! I switched to a 50mm to couple with my Askar 130PHQ, so don’t have the 32mm anymore.