You buy a refractor for imaging, and the first thing you learn is that you need a field flattener. Then you learn that the flattener has to match your scope's focal length and field curvature, and the spacing from flattener to sensor has to be precise, and the whole assembly adds weight and length and one more potential source of tilt. It works — but it's a workaround for a problem that the optical system itself created.
The AT106EDQ builds the correction into the optical system. Four elements in two groups: an apochromatic ED triplet objective handles color correction and image formation, and a separate internal ED field-flattening group flattens the field. The result is a 44mm corrected image circle — flat, sharp, round stars from center to the corners of a full-frame sensor — with nothing between the focuser and your camera but air. No external flattener. No spacing guesswork. No adapter stack.
At 106mm of aperture and 742mm f/7, the AT106EDQ sits in the middle of the EDQ line — more aperture and reach than the AT86EDQ, more portable and mount-friendly than the AT126EDQ. It's the size where you start seeing real deep-sky structure in your images and at the eyepiece, without needing a pier-mounted equatorial to carry it.
The Quad Optical Design
The AT106EDQ uses a four-lens, two-group optical system. The front group is an apochromatic triplet with one ED element — this controls chromatic aberration and forms the primary image. Behind it, a separate group containing a second ED element flattens the focal plane. The two groups are designed as a matched system: the triplet delivers a sharp, color-corrected image, and the flattener ensures that image lands flat across sensors up to 36×24mm.
All lens surfaces carry fully multicoated antireflection coatings matched to their specific glass types. The result is high light transmission, excellent contrast, and images free of the faint color halos that show up around bright stars in less-corrected optics. At f/7, chromatic aberration is tightly controlled — bright stars are clean, the lunar limb is crisp, and planetary discs show color fidelity that does justice to what's actually there.
Built-In Flat Field — No Flattener Required
This is the core advantage of the EDQ design. With a standard triplet or doublet refractor, the focal plane curves. Stars are sharp in the center but stretch toward the edges as the curved focal surface diverges from the flat chip. You add a field flattener to fix it — an extra piece of glass, an extra connection, extra spacing to get right.
The AT106EDQ eliminates that step. The internal ED field-flattening group is optically matched to the objective because it was designed as part of the same system — not added after the fact by a third-party manufacturer. The 44mm corrected image circle covers full-frame sensors with round stars from center to corners. Bolt the camera to the focuser and shoot.
If you want a faster system, the dedicated ATEDQR 0.8× reducer drops the AT106EDQ from 742mm f/7 to approximately 594mm f/5.6 — a 56% increase in light per pixel, shorter exposures, and a wider field. Because the field is already flat at the native focal length, the reducer's job is straightforward focal reduction rather than trying to correct and reduce simultaneously.
Under the Night Sky
106mm of aperture in a well-corrected refractor puts you in a productive range for both visual observing and imaging. The resolution limit is 1.3 arc seconds — enough to split moderately tight doubles and resolve fine structure on the Moon and planets.
Moon: The AT106EDQ shows the Moon in impressive detail. Plato's craterlets begin to emerge under steady seeing. The Straight Wall is a clean, sharp feature at any power. Copernicus shows terraced walls and the central peak cluster. The Alpine Valley is resolved as a distinct channel, and the smaller rilles across the maria show up under good conditions at 150× and above.
Planets: Jupiter shows the two main equatorial belts with internal detail — festoons, barges, and the Great Red Spot with visible structure on the best nights. Shadow transits are clean black dots. Saturn's Cassini Division is a crisp, dark gap at moderate power, and the planet's belted disc shows subtle banding. Mars at opposition shows dark surface markings and the polar cap with the clean color rendition that a well-corrected refractor delivers.
Double stars: With a 1.3 arc second Dawes limit, the AT106EDQ splits the classic doubles cleanly. Epsilon Lyrae (the Double Double) separates at 150×. Albireo is a dramatic color-contrast pair at low power. Castor splits easily. Tighter pairs like Zeta Herculis (1.4") are within reach under steady seeing. The clean Airy discs and high contrast of a good refractor make doubles one of its best visual subjects.
Deep sky: 106mm gathers enough light to show real structure in the brighter Messier objects. M13 shows individual stars resolving across its face at 100× and above. M42 delivers the four Trapezium stars crisply with nebulosity streaming outward. M57 (the Ring Nebula) shows its annular shape clearly. Open clusters like the Double Cluster, M35, and M37 are spectacular — and the flat field means stars at the edge of the eyepiece are as sharp as those in the center. That flat field is a visual advantage too, not just an imaging one.
For the Imager
The AT106EDQ was designed with imaging in mind. At 742mm f/7 with a flat field to full frame, it frames deep-sky targets at a versatile image scale — enough focal length that mid-size targets like the Crab Nebula, the Leo Triplet, and the Veil Nebula East or West arcs fill an APS-C frame with detail, and enough field of view on full frame that larger targets like the Rosette or the North America Nebula fit comfortably.
Add the ATEDQR 0.8× reducer and the system drops to approximately 594mm f/5.6. The wider field frames bigger targets — M31 with both companions, the Heart and Soul complex, wide Milky Way fields — and the faster focal ratio cuts exposure times. The 56% increase in light per pixel means shorter subs or deeper signal in the same integration time.
The camera angle adjuster is standard equipment — rotate the camera to frame your target in landscape, portrait, or any angle in between. The focuser drawtube has a millimeter scale for recording focus positions, and the focus lock prevents shift during long exposures. The focuser is compatible with electronic focusers like the ZWO EAF for remote focusing.
The Mid-Size Sweet Spot
The EDQ line spans three apertures: 86mm, 106mm, and 126mm. The AT86EDQ is the grab-and-go — light, compact, airline-friendly. The AT126EDQ is the heavyweight — maximum aperture and resolution, but 17.67 pounds on the mount. The AT106EDQ sits between them, and that middle position is its strength.
At 14.33 pounds with rings and dovetail, the AT106EDQ rides comfortably on a ZWO AM5, an iOptron GEM28, or an HEQ5-class equatorial mount — the mounts most amateur imagers actually own. It doesn't demand a pier-mounted EQ6 or a permanent setup. At 23.6 inches retracted, it's manageable to carry out to the backyard in one trip. And 106mm of aperture gathers 52% more light than the 86mm version — enough to make a visible difference in exposure times and the faintness of structure you can reach.
If you're looking for a refractor that images flat out of the box, works on a mid-weight mount, and gives you enough aperture to do serious work without the weight and cost of the 126mm, this is the one that threads that needle.
The Focuser
The AT106EDQ's 3.2" rack-and-pinion focuser is built for imaging loads. The right focus knob has a concentric 10:1 fine-focus knob for precise control during critical focusing. The focuser drawtube terminates in a built-in camera angle adjuster that rotates a full 360° and locks at any position — standard equipment, not an extra-cost accessory.
Thread options include M63, M54, and M48 — connecting reducers, filter wheels, and cameras without stacking adapters. The 2" accessory holder uses non-marring brass compression rings, and a 1.25" adapter is included for smaller eyepieces.
The drawtube has a millimeter scale for recording focus positions. A lock knob under the focuser secures focus during imaging. The focuser is compatible with electronic focusers like the ZWO EAF for motorized, software-controlled focusing.
Build and Mechanical
The AT106EDQ is finished in matte black anodize with black-anodized focuser and red accent appointments. The retractable dew shield slides forward from 23.6" retracted to 29.3" extended — functional for dew prevention and stray light control, and self-storing so there's nothing extra to track.
The scope ships with felt-lined hinged split mounting rings with M6×1 thread mounting holes in the top and bottom of each ring. A Vixen-style dovetail and a handle with a mini Vixen saddle plate are included. For heavier equatorial mounts, the rings accept a Losmandy-style D-plate dovetail (sold separately). A dovetail shoe on the upper focuser accepts optional finders or guide scopes.
At 14.33 pounds with rings, dovetail, and handle (heaviest single component 12.6 pounds), the AT106EDQ is manageable for one-person setup on mid-weight mounts.
What's Included
- AT106EDQ 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
- 2" accessory holder with brass compression ring
- 1.25" accessory adapter with brass compression ring
- Retractable dew shield
- Finderscope mounting shoe
- Slip-on metal dust cap
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 — not bolted on as an afterthought.
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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. Stars are round from center to corners across full-frame (36×24mm) sensors. No separate flattener to buy, no spacing to calculate.
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106mm aperture at 742mm f/7. The mid-size EDQ — enough aperture for serious deep-sky imaging and visual observing, at a weight and size that works on mid-range equatorial mounts.
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Fully multicoated optics. All air-to-glass surfaces carry antireflection multicoatings matched to their glass types. High light transmission, excellent contrast, and clean images free of color fringing.
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Compatible with the ATEDQR 0.8× reducer. Add the dedicated reducer (sold separately) to drop from 742mm f/7 to ~594mm f/5.6 — 56% more light per pixel, shorter exposures, wider field — while preserving the flat field.
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3.2" dual-speed rack-and-pinion focuser with 10:1 fine focus. Precise, imaging-capable, with ribbed knobs operable in gloves. Focus lock, mm-scale drawtube markings, and EAF compatibility.
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Built-in camera angle adjuster. 360° rotation standard — not an extra-cost accessory. Frame targets in any orientation without disassembling the imaging train.
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M63, M54, and M48 focuser threads. Multiple thread options for connecting reducers, filter wheels, and cameras without adapter stacks.
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Non-marring brass compression rings. Both 2" and 1.25" accessory holders grip without scratching your eyepiece or accessory barrels.
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Retractable dew shield. Self-storing — slides forward for use, retracts for transport. Controls dew and stray light.
Observing Tip
The AT106EDQ's flat field makes it a natural for visual sweeping of star-rich Milky Way fields and open clusters. Drop in a wide-field 2" eyepiece — a 30mm or 35mm — and sweep through Cygnus, Sagittarius, or the Perseus arm. Stars are sharp to the edge of the field, not just in the center. That's the visual payoff of the built-in flattener: you see stars as points everywhere in the field of view, which makes rich star fields and open clusters noticeably more satisfying than through a conventional refractor where the edge stars stretch.
Frequently Asked Questions
Do I need a separate field flattener with this scope?
No. The AT106EDQ has a built-in ED field-flattening group that delivers a flat, corrected field across full-frame sensors. No external flattener needed. The only optional optic is the ATEDQR 0.8× reducer if you want a faster focal ratio and wider field.
How does this compare to the AT86EDQ and AT126EDQ?
Same optical design in three apertures. The AT86EDQ (86mm, 602mm f/7, ~11 lbs) is the grab-and-go — lightest, shortest, airline-capable. The AT126EDQ (126mm, 882mm f/7, ~17.7 lbs) has the most aperture and resolution but needs a heavier mount. The AT106EDQ (106mm, 742mm f/7, ~14.3 lbs) is the middle ground — 52% more light than the 86, manageable on mounts like the AM5 or HEQ5, and $700 less than the 126. If you want one EDQ that balances aperture, portability, and mount compatibility, this is it.
What mount do I need?
At 14.33 lbs with rings and dovetail, the AT106EDQ works well on a ZWO AM5, iOptron GEM28, or HEQ5-class equatorial for imaging. For visual use, a solid alt-az mount or lighter equatorial will handle it. This is manageable for backyard one-person setup — no permanent pier required.
Can I use this visually, or is it imaging-only?
The AT106EDQ works beautifully for visual observing. 106mm of well-corrected aperture delivers excellent planetary, double star, and deep-sky views. The flat field is a visual advantage too — stars are sharp to the edge of wide-field eyepieces, which makes open clusters and Milky Way sweeping particularly rewarding.
Does this come with a finder?
A finderscope mounting shoe is included on the focuser housing, but you'll need to add your own finder or guide scope. This lets you choose the setup that matches your use — a red-dot finder for visual, or a guide scope for autoguided imaging.
Accessories
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ATEDQR 0.8× Reducer: Drops the AT106EDQ from 742mm f/7 to ~594mm f/5.6. Faster exposures, wider field, full-frame coverage. Designed specifically for the EDQ series.
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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.
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Finder or guide scope: The AT106EDQ ships with a finderscope shoe but no finder. Add a red-dot finder for visual use or a guide scope for autoguided imaging.
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ZWO EAF electronic focuser: Compatible with the AT106EDQ's focuser for motorized, software-controlled focusing during remote imaging sessions.
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ATDUP13 Losmandy D-Plate ($79.95): Upgrade from the included Vixen dovetail for heavier equatorial mounts with Losmandy saddles.
Final Thoughts
The AT106EDQ is the mid-size quad in the Astro-Tech EDQ line — 106mm of aperture at 742mm f/7 with a built-in ED field flattener that delivers round stars across full-frame sensors without an external corrector. For imagers, it means a shorter, simpler optical train and one less thing to get wrong on setup night. For visual observers, it means 106mm of clean refractor aperture with a flat field that makes wide-field sweeping and open clusters look the way they should. At 14.33 pounds, it rides comfortably on the mounts most amateur imagers already own. Add the 0.8× reducer and you have two focal lengths in one scope — f/7 for image scale, f/5.6 for speed. If you want a refractor that images flat out of the box, doesn't demand a heavy mount, and sits at a price point between the compact AT86EDQ and the full-aperture AT126EDQ, the AT106EDQ is the one that balances all three.
