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A 111mm full-frame astrograph with internal focusing and no flattener to fuss with
The William Optics Pleiades 111 is a 111mm f/4.8 apochromatic astrograph built for deep-sky imaging with today's large, heavy cooled cameras. Its seven-element optical design, with three FPL-53 Super ED elements, produces a flat 45mm image circle straight out of the box, so it covers full-frame and APS-C sensors without a separate field flattener or back-focus guesswork beyond the standard 55mm.
It's part of William Optics' WIFD (William Optics Internal Focus Design) series: the focusing lens group moves inside the sealed tube, so there's no drawtube to sag or tilt under a heavy camera, and nothing changes length on the outside as you focus.
Why imagers choose the Pleiades 111
- Fast and wide: f/4.8 with a 528mm focal length frames large nebulae, galaxy groups and star fields, and gathers light quickly for shorter total integration times.
- Full-frame coverage, no flattener: the 45mm image circle covers a 36 x 24mm sensor, and the flattening is built into the seven-element design.
- WIFD internal focuser: a dual-speed rack-and-pinion focuser with 1:10 fine focus and 35mm of travel, a focus position window, and a removable knob for fitting an electronic autofocuser.
- Imaging train built in: an included camera angle rotator and tilt adjuster let you frame targets and correct sensor tilt without buying extra adapters.
- Solid mounting: a 400mm Losmandy-style dovetail, mounting ring and CNC handle with a mini Vixen base for a guide scope.
The Pleiades 111 is designed for astrophotography only and does not support visual observing with eyepieces.
Field of view with popular cameras
| Camera sensor | Field of view | Image scale |
|---|---|---|
| Full frame (36 x 24mm), e.g. ZWO ASI6200 | 3.9° x 2.6° | 1.47"/pixel (3.76µm pixels) |
| APS-C (23.5 x 15.7mm), e.g. ZWO ASI2600MC Pro or ASI2600MM Pro | 2.6° x 1.7° | 1.47"/pixel (3.76µm pixels) |
An APS-C sensor frames targets like the Rosette Nebula, the Orion Nebula with the Running Man, or the Triangulum Galaxy. Full frame takes in larger targets like the Heart Nebula or the North America Nebula.
What you'll need to complete your setup
- A mount: the OTA weighs 17.5 lbs (7.95 kg) and about 22.7 lbs (10.3 kg) with its ring, handle and dovetail. Before adding a camera and guiding, that puts it comfortably on mounts like the ZWO AM5N or the Sky-Watcher Wave 150i.
- A camera: a cooled astronomy camera such as the ZWO ASI2600MC Pro, or a full-frame DSLR or mirrorless camera with the right T-ring. M48 and M54 camera adapters are included.
- Autofocus: the WIFD focuser accepts an electronic focuser such as the ZWO EAFN or EAF Pro. The online manual below shows how to fit it.
- Guiding: the handle's mini Vixen base takes a UniGuide 32 or UniGuide 50 guide scope.
Pleiades 68 vs. 111 vs. 181
| Pleiades 68 | Pleiades 111 | Pleiades 181 | |
|---|---|---|---|
| Aperture | 68mm | 111mm | 181mm |
| Focal length | 260mm | 528mm | 998mm |
| Focal ratio | f/3.8 | f/4.8 | f/5.5 |
| Image circle | 48mm | 45mm | 55mm |
| OTA weight | 6.6 lbs (2.98 kg) | 17.5 lbs (7.95 kg) | 33.1 lbs (15 kg) |
| Best for | Very wide fields and the lightest setup | The balance of reach, speed and portability | Smaller galaxies and medium format cameras |
Why buy from Mile High Astronomy
- No surprise import duties: our price includes all import duties. Telescopes ordered directly from overseas are often listed without duties, which are then billed separately before delivery.
- Ships from the US: your Pleiades 111 ships from our Denver store, not from overseas.
- Expert help from astrophotographers: we can help you choose a mount, camera and focuser for your setup, and we're here to help after the sale.
What's in the box
- William Optics WIFD Pleiades 111 f/4.8 APO astrograph OTA
- Mounting ring and CNC carry handle with mini Vixen base
- 400mm Losmandy-style dovetail plate
- Camera angle rotator and tilt adjuster
- M48 and M54 camera adapters, plus spacer rings
- Bahtinov mask cover (patented)
- Soft carry case
Pleiades 111 FAQ
Do I need a field flattener or reducer?
No. The Pleiades 111 is a seven-element astrograph with the field flattening built in. Set your camera sensor 55mm from the rear flat surface of the telescope using the included adapters and spacers.
Can I use the Pleiades 111 for visual observing?
No. William Optics designed it for imaging only, and it does not support visual use with a diagonal and eyepieces. For a William Optics refractor that does both, ask us about the Gran Turismo and FluoroStar series.
Will it cover a full-frame camera?
Yes. The 45mm image circle covers a full-frame 36 x 24mm sensor, as well as APS-C and smaller sensors.
What does WIFD mean?
WIFD stands for William Optics Internal Focus Design. Instead of moving a drawtube in and out, the focuser slides an optical group inside the sealed tube. The camera stays fixed to the back of the telescope, which prevents image shift and sag under heavy cameras and keeps the optics protected from dust.
What mount do I need?
Plan for about 23 lbs for the telescope with its ring, handle and dovetail, plus your camera, filter wheel, guide scope and focuser. A harmonic or strain-wave mount like the ZWO AM5N or Wave 150i, or a mid-size German equatorial mount, is a good match.
Can I add an electronic focuser?
Yes. The coarse focus knob removes so an electronic focuser like the ZWO EAFN can drive the focuser directly. Installation steps are in the online manual.
Specifications
| Optical design | 7-element apochromatic astrograph |
| Glass | FPL-53 (3 Super ED elements) |
| Aperture | 111mm |
| Focal length | 528mm |
| Focal ratio | f/4.8 |
| Image circle | 45mm |
| Back focus | 55mm from the rear flat surface |
| Camera formats | Full frame, APS-C and smaller |
| Field flattener | None required |
| Focuser | WIFD internal dual-speed rack and pinion, 1:10 fine focus, EAF compatible |
| Focuser travel | 35mm |
| Included adapters | Tilt adjuster, rotator, M48 and M54 camera adapters |
| Dovetail | 400mm Losmandy style |
| Tube length | 645mm (dew shield retracted) to 785mm (extended) |
| Dew shield outer diameter (for solar filter) | 140mm |
| OTA weight | 17.5 lbs (7.95 kg) |
| Total weight with ring, handle and dovetail | 22.7 lbs (10.3 kg) |
| Visual use | Not supported (imaging only) |
| Manufacturer part number | T-P-111BU |
Online manual: back focus adjustment, electronic focuser installation, tilt adjustment and focuser tension.