Alan Dyer reviewed the AT86EDQ for Sky & Telescope (July 2025) and called it one of his picks for a desert-island telescope — the one scope he'd take if he could only take one. That's a statement worth unpacking, because this is an 86mm refractor. It's not trying to be the biggest aperture on the field. What it's trying to be is the most versatile small refractor you can buy, and it gets there by doing something most small refractors don't: delivering a flat, corrected field straight from the focuser, with no external flattener required.
The AT86EDQ is a four-element, two-group quadruplet. The front group is an apochromatic triplet with one ED element for color correction. Behind it, a separate internal group containing a second ED element flattens the field. The result is a 44mm corrected image circle — flat, round stars from the center to the corners of a full-frame sensor — with nothing between the focuser and your camera but the included photographic extension tube. No separate field flattener to buy. No spacing to calculate. No wondering whether a generic corrector is well-matched to your scope's optical system. It's done.
At 86mm of aperture, 602mm f/7, and 18.2 inches retracted, the AT86EDQ is genuinely grab-and-go. It fits on lightweight mounts. It fits in overhead airline compartments. It sets up in minutes and delivers images and views that belie its compact size.
S&T Tested
Alan Dyer's Sky & Telescope review (July 2025) put the AT86EDQ through rigorous visual and photographic testing. His star test at 200× on Capella showed a well-defined central Airy disc with a clean first diffraction ring — he noted the optics passed the star test by a margin that matched or exceeded any telescope he'd reviewed in recent years. Visually, he found no blue or magenta halo from chromatic aberration — the optics were clean on planets, bright stars, and wide-field deep-sky targets alike. At f/7 on a Canon R5 (full-frame, 45 megapixels), the internal flattener delivered sharp stars to the corners of the frame with no astigmatism or color flaring. The quad design also proved forgiving of backfocus spacing — within a couple of millimeters either direction, Dyer saw no significant degradation.
The Quad Optical Design
The AT86EDQ uses a four-lens, two-group optical system. The front group is an apochromatic triplet with one ED element — this handles color correction and primary image formation. Behind it, a separate group containing a second ED element flattens the focal plane. All lens surfaces carry fully multicoated antireflection coatings matched to their specific glass types. The blackened tube interior has five knife-edge baffles, and the focuser includes additional ribs for stray-light suppression.
The two groups are designed as a matched system: the triplet delivers a sharp, color-free image, and the flattener ensures that image lands flat across sensors up to full frame. This is not a triplet with a generic corrector bolted on — the field-flattening group is integral to the optical design, which is why the correction is as clean as it is.
Built-In Flat Field — No Flattener Required
This is the defining advantage of the EDQ design. With a conventional triplet or doublet, the focal plane curves. Stars in the center are sharp, but stars toward the edges elongate as the curved focal surface diverges from the flat sensor. An external field flattener corrects this — but it's a separate purchase, a separate connection, and a separate spacing calculation.
The AT86EDQ eliminates that step. The 44mm corrected image circle covers full-frame sensors (36×24mm) with round stars from center to corners. Alan Dyer's imaging tests on a Canon R5 confirmed excellent field illumination at f/7 — only gradual, minimal vignetting across the frame. Bolt the camera to the extension tube and shoot.
If you want a faster system, the dedicated ATEDQR 0.8× reducer (sold separately) drops the AT86EDQ from 602mm f/7 to approximately 482mm f/5.6 — almost a full stop faster, shorter exposures, and a wider field. The reducer attaches directly to the focuser's M69 threads (the step-down ring is removed first). Dyer's tests showed the reducer preserved the flat field well, with only minor elongation visible at the extreme corners at pixel-peeping magnification.
Under the Night Sky
86mm of aperture in a well-corrected refractor is more capable than many people expect. The resolution limit is 1.35 arc seconds, and the clean optics deliver high-contrast views that punch above their aperture class.
Moon: The AT86EDQ shows crisp lunar detail — crater walls, central peaks, and the larger rilles are well-defined. At 86× (7mm eyepiece), you're seeing the full disc with sharp detail across the field. Push to 150× with a 4mm eyepiece and the terminator comes alive — Copernicus shows terraced walls, Plato's floor shows texture, and the Straight Wall is a clean, sharp shadow line.
Planets: At 150× with an Astro-Tech 4mm 82° UWA, Dyer reported Mars showing the North Polar Cap and Syrtis Major clearly during the January 2025 planetary alignment. Jupiter's dark belts showed hints of fine structure, and the Galilean moons were tight points of light. Venus presented a clean white crescent phase with no false color — none of the blue or magenta halo that lesser optics produce. Saturn's Cassini Division is visible at moderate power under steady seeing, and the planet's disc shows subtle banding.
Double stars: With a 1.35 arc second Dawes limit, the AT86EDQ splits the classic visual doubles. Epsilon Lyrae (the Double Double) resolves at 150×. Albireo is a striking color-contrast pair at low power. Castor separates cleanly. Dyer noted that Rigel showed its 7th-magnitude companion 9.4 arc seconds from the brilliant primary — a test of contrast as much as resolution — and that Castor split cleanly into its slightly unequal components at 5.6 arc seconds.
Deep sky: The flat field is a visual advantage as well as a photographic one. Stars are sharp to the edge of the eyepiece field, which makes open clusters and Milky Way sweeping noticeably better than through a conventional refractor. Dyer paired the AT86EDQ with an Astro-Tech 20mm 100° XWA and reported sharp stars to the edges of the field across wide Milky Way vistas. M42 framed beautifully in the 3.3° field with surrounding nebulosity and clusters. The Messier open clusters — M35, M36, M37, M38, the Double Cluster — are spectacular subjects for this scope, with pinpoint stars across the field.
For the Imager
The AT86EDQ was designed around imaging, and the S&T review confirmed it delivers. At 602mm f/7 on a Canon R5 (full-frame, 4.4-micron pixels), Dyer found no astigmatism or color flaring in the corners of the frame. The internal flattener was doing its job — flat field, round stars, clean correction.
At this focal length, the field of view on a full-frame sensor is roughly 3.4° × 2.3° — wide enough for the Orion Nebula complex, the Rosette, large open clusters, and widefield Milky Way shots. Add the 0.8× reducer and the field opens to approximately 4.2° × 2.8° at f/5.6 — nearly a full stop faster with a significantly wider framing.
The scope includes a photographic extension tube that threads into the camera angle adjuster when you're ready to image. The extension tube provides M63, M54, and M48 thread options for connecting cameras and accessories. A set of camera adapter rings (M54 and M48 sizes) is also included, along with 0.5mm and 1mm backfocus shims for fine-tuning sensor spacing. The recommended backfocus is forgiving — Dyer tested ±2mm from the nominal spacing and saw no significant degradation at either f/7 or f/5.6.
The camera angle adjuster rotates a full 360° and locks with a large knob — frame your target in landscape, portrait, or any angle between without disassembling the imaging train. The focuser is compatible with electronic focusers like the ZWO EAF for remote, software-controlled focusing.
Grab-and-Go
At 18.2 inches retracted, 22 inches with the dew shield extended, and approximately 11 pounds with rings and dovetail, the AT86EDQ is the smallest and lightest scope in the EDQ line. It rides comfortably on a ZWO AM3 or AM5, an iOptron GEM28, or any equatorial mount in that class. For visual use, a sturdy alt-az mount or a light equatorial handles it easily.
The scope fits in airline overhead compartments — not all refractors can say that. If you travel to dark sky sites or want a scope that sets up in minutes for a quick session from the backyard, the AT86EDQ's size and weight are a genuine advantage. The included cordura carry case protects it in transit.
The Focuser
The AT86EDQ's 3.2" (81mm) rack-and-pinion focuser has 85mm of travel — enough for most eyepiece and camera configurations. The right focus knob has a concentric 10:1 fine-focus knob for precise control. The focuser locks solidly with no image shift when tightened, and Dyer noted it didn't slide out of focus or slip when aimed straight up while carrying a heavy eyepiece and diagonal.
The focuser drawtube terminates in a built-in camera angle adjuster — standard equipment, not an extra-cost accessory. The drawtube has a scale marked in 1mm increments for recording focus positions. Thread options include M63, M54, and M48 via the included adapter set.
The 2" and 1.25" accessory holders use non-marring brass compression rings. The existing Astro-Tech 1.25" dielectric diagonal is a good pairing for visual use — the product page recommends it specifically.
Build and Mechanical
The AT86EDQ is finished in matte black anodize with red-anodized focuser and camera angle adjuster appointments. Five knife-edge baffles inside the tube control stray light, and the focuser adds additional suppression ribs. The retractable dew shield slides forward 95mm for dew protection and stray-light control.
Felt-lined hinged split mounting rings with M6×1 thread mounting holes come standard, along with a Vixen-style dovetail and a handle with a mini Vixen saddle plate. The rings accept a Losmandy-style D-plate dovetail (sold separately) for heavier mounts. A single Synta-standard finderscope shoe is included on the focuser housing.
What's Included
- AT86EDQ optical tube assembly
- Felt-lined hinged split mounting rings (pair) with M6×1 mounting holes
- Carrying handle with mini Vixen saddle plate
- Vixen-style dovetail plate (24cm)
- Photographic extension tube (M63, M54, M48 threads)
- Camera adapter ring set (M54 and M48 sizes)
- Backfocus shims (0.5mm and 1mm)
- 2" accessory holder with brass compression ring
- 1.25" accessory adapter with brass compression ring
- Retractable dew shield
- Finderscope mounting shoe (Synta-standard)
- Slip-on metal dust cap
- Cordura nylon carry case
Community Says
"Build quality is excellent. Baffling of both the OTA and focuser assembly is well executed. Quite impressive actually. The focuser is beefy and..."
— Cloudy Nights AT86EDQ discussion. This owner logged over 80 hours behind the AT86EDQ for visual observing and found it impressive on solar, Venus, and planets.
"On open clusters, it delivered pinpoint stars edge to edge."
— Cloudy Nights AT86EDQ Owners Thread. This owner used the scope visually on Scorpius and Sagittarius summer targets and also noted: "I cannot see that it gives up anything to my FCD-100 or FPL-53 triplets."
"I have used this scope quite a bit and have found it to be excellent. The build quality is outstanding and the optics are quite good. With and without the reducer, the stars are sharp all the way to the edge of an aps-c sized sensor."
— Cloudy Nights AT86EDQ discussion. This owner tested the AT86EDQ both visually and photographically.
"Sharp and clean and I could see faint bandings on the disc of Saturn, something I'm not sure I've noticed on the 14-inch dob."
— Cloudy Nights AT86EDQ Owners Thread. This owner came to the AT86EDQ from a 14" Dobsonian and was struck by the refractor's planetary contrast.
Features
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Quadruplet optical system with two ED elements. Four-lens, two-group design: an apochromatic ED triplet objective plus a separate internal ED field-flattening group. Color correction and flat field are built into the optical system. S&T star test: at least ¼-wave, with no false color on planets or bright stars.
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Built-in flat field to full frame — no external flattener required. The internal ED field-flattening group delivers a 44mm corrected image circle. Round stars from center to corners on full-frame sensors, confirmed by S&T testing on a Canon R5.
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86mm aperture at 602mm f/7 — grab-and-go size. 18.2" retracted, ~11 lbs with rings. Fits on lightweight mounts and in airline overhead compartments. Sets up in minutes.
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S&T reviewed (July 2025). Alan Dyer: "one of my picks for a desert-island telescope." Passed the star test by a margin matching or exceeding any scope recently reviewed.
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Forgiving backfocus spacing. S&T testing showed ±2mm from nominal had no significant effect on image quality at either f/7 or f/5.6. Less fiddling on setup night.
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Compatible with the ATEDQR 0.8× reducer. Add the dedicated reducer (sold separately) to drop from 602mm f/7 to ~482mm f/5.6 — almost a full stop faster, wider field, shorter exposures.
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3.2" dual-speed rack-and-pinion focuser with 10:1 fine focus. 85mm of travel, solid lock with no image shift, mm-scale drawtube markings. EAF compatible.
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Built-in camera angle adjuster. 360° rotation standard — frame targets in any orientation without disassembling the imaging train.
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Photographic extension tube and adapter set included. M63, M54, and M48 thread options. Camera adapter rings and backfocus shims included in the box — not sold separately.
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Five knife-edge baffles plus focuser suppression ribs. Thorough internal stray-light control for high contrast on planets and deep sky.
Observing Tip
The AT86EDQ at 602mm f/7 with a wide-field eyepiece is one of the best open-cluster scopes you can own. Drop in a 20mm 100° eyepiece (30×, 3.3° true field) and sweep through the Milky Way from Cygnus to Sagittarius. The flat field means every star in that 3.3° field is a point — not a smear — from center to edge. Open clusters pop against the background in a way that scopes with curved fields don't quite match. For M35, M36, M37, M38, and the Double Cluster, this is hard to beat at any price.
Frequently Asked Questions
Do I need a separate field flattener?
No. The AT86EDQ has a built-in ED field-flattening group that delivers a flat, corrected field across full-frame sensors. No external flattener needed — this is one of the primary advantages of the quad design. The only optional optic is the ATEDQR 0.8× reducer if you want a faster focal ratio and wider field.
What mount do I need?
At ~11 lbs with rings and dovetail, the AT86EDQ is light enough for mounts like the ZWO AM3 or AM5, iOptron GEM28, or a Sky-Watcher HEQ5. For visual use, a sturdy alt-az mount handles it well. This is a genuinely portable scope — it doesn't demand a heavy mount.
How does this compare to the AT90EDX or AT90CFT?
Different designs for different priorities. The AT90EDX/CFT is a 90mm f/6 FCD-100 triplet with a guaranteed .95 Strehl ratio — premium optics with the highest-grade glass. But it needs a separate field flattener for imaging. The AT86EDQ is a quad with a built-in flat field — you give up 4mm of aperture and the Strehl guarantee, but you gain a simpler imaging train and no external flattener. Both are excellent visual scopes. CN users who own both report comparable visual performance on planets and double stars.
Can I use this just for visual observing?
Absolutely. Multiple CN owners use the AT86EDQ exclusively for visual and report excellent results on planets, double stars, open clusters, and deep sky. The flat field is a visual advantage too — stars are sharp to the edge of wide-field eyepieces, which makes sweeping and cluster observing noticeably better.
How does the AT86EDQ compare to the AT106EDQ and AT126EDQ?
Same optical design in three aperture sizes, all f/7. The AT86EDQ (86mm, 602mm, ~11 lbs) is the grab-and-go — lightest, shortest, airline-capable. The AT106EDQ (106mm, 742mm, ~14 lbs) is the mid-size option with 52% more light grasp. The AT126EDQ (126mm, 882mm, ~17.7 lbs) is the big one — most aperture and resolution, heaviest mount requirements. All share the ATEDQR 0.8× reducer and the built-in flat field.
What did S&T note as drawbacks?
Alan Dyer noted three things: the focuser tube itself doesn't rotate (the camera angle adjuster handles rotation instead, but lacks index markings for repeatable positioning), and threading 48mm filters into the adapter ring was difficult. These are minor mechanical issues — the optics and optical performance drew no complaints.
Accessories
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ATEDQR 0.8× Reducer (sold separately): Drops the AT86EDQ from 602mm f/7 to ~482mm f/5.6. Almost a full stop faster, wider field, full-frame coverage. Threads directly to the focuser's M69 threads (remove the step-down ring first).
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T-ring for your camera mount: Required for connecting DSLR and mirrorless cameras. Dedicated CMOS/CCD astronomy cameras typically have 48mm T-threads built in and connect directly via the included adapter rings.
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Astro-Tech 1.25" Dielectric Diagonal (AT1D): Recommended on the product page for visual use. High-reflectivity dielectric coating.
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Finder or guide scope: The AT86EDQ ships with one finderscope shoe. Add a red-dot finder for visual use or a guide scope for autoguided imaging. Consider a second shoe if you want both.
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ZWO EAF electronic focuser: Compatible with the AT86EDQ's focuser for motorized, software-controlled focusing.
Final Thoughts
The AT86EDQ is the smallest flat-field quad in the Astro-Tech line — 86mm of aperture at 602mm f/7 with a built-in ED field flattener that delivers round stars across full-frame sensors without an external corrector. Alan Dyer put it through a full S&T review and found optics that matched or exceeded anything he'd tested recently, with a star test that was textbook-clean and imaging performance that held up on a 45-megapixel full-frame camera. The CN community calls it excellent for visual, excellent for imaging, and built like it means business. At 18.2 inches retracted and roughly 11 pounds, it goes where you go — backyard, dark sky site, or the overhead bin of a 737. If you want one refractor that does visual and imaging without compromise and without needing a separate flattener, and you want to actually carry it out to the backyard on a weeknight, this is the scope that earns that job.
