William Optics has been a key producer of good-value small refractors in recent times, and its Pleiades 68 presents a highly desirable astrograph that ticks so many boxes that, after reviewing it, we were reluctant to send it back!
Everything about this little refractor just exudes attention to detail, from the matching logos on the carry case and telescope, to the quality of the machining.
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But these aren’t as important as its performance, so we were anxious to put it to the test.
With a focal length of 258mm, the 68mm apochromatic objective lens provides a speedy f/3.8 focal ratio.
This means a very wide field of view and a telescope designed for use with large, full-frame astronomy cameras.
Setting up the William Optics Pleiades 68 astrograph
We matched the William Optics Pleiades 68 astrograph to our full-frame Atik camera (with large 9µm pixels) using the supplied M54 connector.
However, we also required an Askar precision adjustable spacer, which was provided by the Widescreen Centre.
The WIFD focusing system requires camera back focus to be set to exactly 55mm, and we appreciated the detailed and informative manual on the William Optics website to assist with this somewhat fiddly initial set-up process.
With our camera attached, we found that the WIFD format made for a central balance position and it sat securely on its 210mm Vixen-style dovetail bar.
A matching 32mm Uniguide scope is available to purchase separately and sits atop the saddle handlebar.
Once the initial spacing is all finalised, this is a simple telescope to use and very desirable for travelling astronomy.
Almost everything is adjustable on the Pleiades 68, including camera rotation and focuser tension, and there’s even a tilt adjuster.
Each feature is explained clearly in the manual, with detailed diagrams. One side of the focuser knob contains a thermometer dial.
How it performs
During our review period with the William Optics Pleiades 68 astrograph, the nighttime temperatures were stable.
Once we initially focused only miniscule adjustments were necessary throughout our relatively short sessions, dictated by summer nights in the UK.
Reduced darkness notwithstanding, the late summer brought some of the most impressive nebulous regions around the Milky Way, and the Pleiades 68 is made for sucking these huge sky areas in and doing justice to them on camera.
To make the best of our clear sky time, we used narrowband hydrogen-alpha (Ha) and oxygen (OIII) filters and applied 2x2 camera binning for some targets to increase light sensitivity.
Our first session was on the Elephant’s Trunk Nebula.
The little scope easily framed the whole scene and when we saw the first image roll in, the Pleiades 68 put a big smile on our face.
Star shapes were very good and well handled in the corners.
Beautiful image results were achieved every time we had a clear spell: the North America Nebula and Pelican Nebula, the entire Veil Nebula in all its glory, the Heart and Soul Nebulae in Cassiopeia, the Butterfly Nebula near Sadr, and a sneaky early session on the Andromeda Galaxy.
We even managed to get some results on the Eagle Nebula and Swan Nebula, capturing all the swirling hydrogen regions surrounding them, though like Andromeda this target was very low in the sky.
It soon became obvious that this little telescope was allowing us to accomplish much more than we normally do in the way of night-sky imaging in a very short time.
Its ease of use, fast focal ratio and stable image production came together to help us rediscover our enjoyment of the night sky, after a cloudy and dismal start to the year.
The quality of the images was impressive and William Optics’ inclusion of FPL53 glass elements in the design, plus a new lens cell arrangement, have combined to produce, in our opinion, a highly capable, high-quality astrograph, desirable to newcomers to the hobby and veteran astrophotographers alike.
William Optics Pleiades 68 astrograph's seven lenses
The William Optics Pleiades 68 astrograph features an unusual septuplet optical system – no less than seven individual lenses, designed to eliminate the two biggest issues with refractors: chromatic aberration (CA), where the various colours of light tend to come to focus at different points; and field curvature, where stars at the edges of an image deform and stretch.
Fast focal ratios often exacerbate these issues.
Image results from a full-frame camera, with 36 x 24mm imaging area confirmed that the combination of four rear lenses produces reasonable star shapes right into the corners of the image.
Using parfocal RGB filters in turn, we photographed a star in a central position and then again with the star in each extreme corner, noting that there was no significant shift in colour focus across the image plane.
This demonstrated that the three objective lenses bring red, green and blue wavelengths into concentrated points throughout the image, which is crucial for overall sharp focus and essential for one-shot colour cameras.
William Optics Pleiades 68 astrograph best features
WIFD focuser
The patented William Optics Internal Focus Design is a welcome innovation, enabling large-format cameras to achieve full illumination without vignetting. No external movement is observed during adjustment, as the internal mechanism moves the four rear optical elements forward and back to achieve focus. The silky-smooth twin-speed setup offers outstanding performance.
Bahtinov mask
A favourite feature of ours, the dust cap has a removable plate that unscrews to reveal a Bahtinov mask. This makes precise manual focusing of the telescope a quick and simple task, even though miniscule movements of the fine-focusing knob are required for perfect sharpness at this focal length and f/ ratio.
Adaptors and spacers
The back spacing of the camera is critical with the Pleiades 68. This is made easier by the choice of rear camera fittings, with removable M48 and M54 threaded adaptors on the telescope, while a selection of thin Delrin rings make for millimetre-perfect adjustment to the required 55mm back focus.
Camera rotator/tilt adaptor
Finding the perfect camera position to best frame your target is easy, thanks to the rear camera rotator, which is secured in place with a chunky knurled thumbscrew. Removing the thumbscrew and the adjacent blue ring, which is handily marked in 1° increments, reveals the camera tilt adaptor screws.
Carry case
The branded soft carrying case is stylish, well padded and easily able to protect the telescope during storage or while travelling. It enhances the portability of the Pleiades 68 and makes it a practical size for carry-on aircraft luggage. A handy set of Allen keys is included within the case.
- Price: £2,098; £2,197 with guidescope
- Optics: FPL53 apochromatic septuplet
- Aperture: 68mm
- Focal length: 258mm, f/3.8
- Focuser: Internal rack and pinion
- Extras: Dovetail bar, tube rings, carry handle, padded case
- Weight: 3.83kg
- Supplier: The Widescreen Centre
- Tel: 01353 776199
- www.widescreen-centre.co.uk
This review appeared in the January 2025 issue of BBC Sky at Night Magazine
