There's a moment in every refractor owner's life when the view snaps into focus and the background goes black — truly black, the way only a well-corrected triplet delivers it — and whatever you're looking at just hangs there in space, pinpoint and still, with a clarity that makes you forget you're looking through glass at all. The AT115EDT is a 115mm f/7 ED triplet that exists to deliver that moment, night after night, without costing what a premium APO costs. It won't do everything. It won't hunt down magnitude-14 galaxies or replace a 12-inch Dob for faint fuzzies. But for planets, the Moon, double stars, bright deep-sky, and serious astrophotography, it does what refractors do better than any other optical design — and at 115mm, it gathers over 27% more light than the 102mm refractors it often sits next to on the shelf.
The Optics
Triplet apochromatic with an FK-61 ED center element — that's Schott's FPL-51 equivalent, slow-polished for smooth surfaces and low scattered light. Three lens elements, fully multicoated on all air-to-glass surfaces. The result is what refractor people are actually paying for: high contrast, pinpoint stars, and virtually no chromatic aberration at the focal plane. At 805mm focal length and f/7, the AT115EDT is fast enough for efficient imaging but slow enough to be forgiving on eyepiece quality. The internal light baffles are knife-edge design, and the lens edges are blackened — both details that contribute to the deep, dark sky backgrounds this scope is known for. Ed Ting's review on Cloudy Nights noted the AT115EDT delivered excellent views of planets, the Moon, and double stars — and called it a strong recommendation.
The Focuser
This is where the AT115EDT quietly separates itself from competitors in its price class. The 3.2" dual-speed rack-and-pinion focuser has two coarse focusing knobs and a concentric 10:1 fine-focus microknob. Ninety-five millimeters of travel with a millimeter scale on the drawtube for repeatable photographic focus. A lock knob underneath holds your position. One Cloudy Nights member tested the focuser by loading a 2" diagonal, a 28mm UWA eyepiece, and an actual brick onto the drawtube — 8.2 pounds total. He could position the focuser anywhere and it held, with the fine-focus knob still raising and lowering the load with precision. You will not need to do this. But knowing you could says something about the mechanical quality.
The focuser rotates a full 360° for camera framing — loosen the knob on top, rotate to your desired angle, tighten. The 2" eyepiece holder includes a built-in camera angle adjuster for fine compositional tweaks without disturbing the heavier focuser body. Both 2" and 1.25" holders use compression rings, not thumbscrews, so your eyepiece and diagonal barrels stay unmarred. These are features that show up on scopes costing significantly more. On the AT115EDT, they're standard.
The Tube and Rings
The 114mm diameter optical tube is finished in white with grey anodized trim — clean, professional, durable. At 27.25" long (32.4" with the retractable dew shield extended), it's compact enough for travel and short enough to balance well on a mid-weight equatorial mount. Total weight with rings, handle, and Losmandy dovetail: 15.25 pounds.
The dual split hinged CNC tube rings are lined with white felt (not black, which can stain white tubes over time). A Losmandy-style dovetail bolts to the rings with a carry handle on top. Two Vixen-style finderscope shoes are mounted on the tube. A slip-on metal dust cap protects the objective, and a dust seal covers the eyepiece holder. The scope also has full collimation capability — three pairs of collimation screws sit under the silver collar at the back of the dew shield.
Astrophotography
At f/7 with 805mm of focal length, the AT115EDT is a serious imaging platform. The focal ratio is fast enough for reasonable exposure times on deep-sky targets but slow enough that stars stay tight across the field without a corrector for visual work. For imaging, pair it with the dedicated 0.8x reducer/flattener to drop to f/5.6 and 644mm — a faster, wider-field imaging configuration with a flat, corrected field across APS-C and full-frame sensors. A 1x field flattener is also available for full focal length imaging with flat stars to the corners.
The camera angle adjuster, compression rings, and rotatable focuser make photographic setup faster and more precise than scopes that lack these features. The focuser's 95mm of travel accommodates virtually any diagonal, camera, and accessory combination without running out of in-focus or needing extension tubes — a versatility that owners consistently praise.
What's Included
- Astro-Tech AT115EDT 115mm f/7 ED triplet refractor OTA
- Dual split hinged CNC tube rings with white felt lining
- Losmandy-style dovetail plate with carry handle
- 2" eyepiece holder with compression ring and camera angle adjuster
- 1.25" adapter with compression ring
- Retractable dew shield
- Metal dust cap and eyepiece holder dust seal
- Soft-sided heavy-duty nylon carry case with foam cutouts for 7 accessories
Features
-
115mm (4.53") FK-61 ED triplet optics — Over 27% more light-gathering than a 102mm refractor. Slow-polished triplet with fully multicoated surfaces for high contrast, pinpoint stars, and minimal chromatic aberration.
-
3.2" dual-speed rack-and-pinion focuser — 10:1 fine-focus ratio, 75mm travel, mm scale, lock knob. Proven to hold 8+ pounds without slipping. The mechanical heart of the telescope.
-
360° rotatable focuser — Frame your camera or position your diagonal at any angle without moving the scope.
-
Built-in camera angle adjuster — Fine-tune composition without disturbing the focuser. Standard equipment, not an optional extra.
-
Compression ring eyepiece holders — 2" and 1.25". No thumbscrews to mar your eyepiece or diagonal barrels.
-
Knife-edge internal baffles — Deep contrast and dark sky backgrounds. Blackened lens edges reduce internal scatter.
-
Retractable dew shield — Slows dew formation and shields the objective from ambient light. Stores flat against the tube for transport.
-
Losmandy dovetail and CNC tube rings — White felt lined rings, carry handle. Ready for Losmandy and compatible saddles out of the box.
-
Soft carry case with accessory storage — Heavy-duty nylon case with paper pockets and foam cutouts for 7 accessories. Everything travels in one bag.
-
Full collimation capability — Three pairs of collimation screws under the dew shield collar. You'll probably never need them, but they're there.
Under the Night Sky
Jupiter at 160x (5mm eyepiece) in the AT115EDT shows the two main equatorial belts with festoons, barges, and the Great Red Spot as a definite salmon-colored oval — not just a smudge, but a feature with shape and internal structure on a steady night. Push to 200x on the best evenings and the belts begin to show scalloping and rifts. Four or five belts become visible at the limits of the seeing. The Galilean moons show disks, not points. The contrast of a well-corrected triplet makes the difference here — the belts are sharply defined against the zones, with none of the scattered light that softens the view in lesser optics.
Saturn at 160x shows Cassini's Division as a clean dark gap, not a thin line. The shadow of the globe on the rings is crisp. The crepe ring is visible against the globe on transparent nights. Titan is obvious; two or three fainter moons show up with averted vision.
The Moon is where refractors earn their keep, and the AT115EDT delivers. At 200x, the terminator is alive with shadow detail — crater walls catching the first light, rilles threading across mare floors, the Straight Wall casting its knife-edge shadow. You're seeing the kind of sharpness and contrast that made refractors the instrument of choice for lunar and planetary observers for four centuries.
Double stars are a refractor specialty. Albireo splits into gold and blue at any magnification. Epsilon Lyrae — the Double Double — cleanly resolves all four components at 200x. At 1.01 arc seconds of resolution, the AT115EDT handles tight pairs that would challenge many 4-inch scopes.
Deep-sky is real but bounded by aperture. The Ring Nebula (M57) shows its annular shape clearly. M13 resolves to individual stars across the face. The Andromeda Galaxy stretches across the field at low power with dark lanes visible on a good night. The Double Cluster in Perseus is a showpiece — dozens of stars scattered across the field with a clarity that only a refractor delivers. What you won't get: the faintest galaxies, the dimmest planetary nebulae, the deep structure in large faint objects. For that, supplement with a larger reflector. The AT115EDT is not trying to be everything. It's trying to be excellent at what refractors do best.
Community Says
"It's difficult for me to consider another refractor that offers this much value. I am completely satisfied with the image quality of this well-built refractor. But most importantly, this refractor compares extremely well to some of the supposedly, more expensive refractors that I have owned and used." This owner's video review of the AT115EDT has been followed by 111 replies and widespread agreement from the Cloudy Nights community. — Cloudy Nights AT115EDT review thread. This owner has experience with multiple refractors at higher price points.
"I am an AT loyalist because of the fine refractors I have always gotten from them. Every review I have seen of the AT115 is very positive." This owner chose the AT115EDT over an Askar 120 APO — not just for the price, but because of long-term trust in the Astro-Tech line. — Cloudy Nights AT115EDT discussion. This owner is a returning Astro-Tech customer.
Observing Tip
The AT115EDT's 15.25 pounds puts it right on the edge of what many mid-weight mounts can handle well. An HEQ5/EQ5-class mount will carry it for visual observing, but for imaging — especially with a camera, guidescope, and accessories — you'll want an EQ6 or Losmandy G11 class mount for stability. Match the mount to the job: if you're visual-only, the lighter mount saves setup time and backache. If you're imaging, don't compromise on mount capacity. The scope deserves a steady platform.
FAQ
How does this compare to a 102mm ED refractor?
The AT115EDT gathers over 27% more light than a 102mm — that's a meaningful jump. You'll see fainter stars, resolve tighter doubles, and collect more signal in less time when imaging. At f/7, the AT115EDT is also faster than most 102mm f/7.8 or f/8 doublets, which means shorter exposures for astrophotography. The dual-speed 3.2" focuser, compression rings, and camera angle adjuster are features that many 102mm scopes at the same price don't include.
Is the FK-61 glass as good as FPL-53?
Different, not lesser — for most uses. FK-61 (FPL-51 equivalent) in a triplet design provides excellent chromatic correction. You might see a faint violet halo on bright stars at high power that an FPL-53 or FCD-100 scope would eliminate. In imaging, it's a non-issue with narrowband or modern broadband filters. In visual use, most owners don't notice it under normal conditions. If absolute chromatic perfection is your priority, look at the AT150EDL (FCD-100 glass) or the AT72EDII (FPL-53 glass, smaller aperture). For the vast majority of observers, the FK-61 triplet gives you more aperture for your money — and more aperture means more resolution, more light, and more capability.
What mount do I need?
For visual observing: an HEQ5-class equatorial mount or a solid alt-az mount handles the AT115EDT well. Total payload with diagonal and eyepiece is around 17 pounds. For astrophotography: step up to an EQ6 or Losmandy G11 class mount to get the stability you need for guided long exposures. The Losmandy dovetail is included, so you're ready for Losmandy-compatible saddles out of the box.
What do I need for astrophotography with this scope?
At minimum: the scope, a sturdy equatorial mount with tracking, a camera (DSLR/mirrorless or dedicated astronomy camera), and a field flattener or reducer/flattener. The AT115EDT's 0.8x reducer/flattener takes you to f/5.6 and 644mm — faster and wider for deep-sky imaging. The 1x flattener keeps you at f/7 and 805mm with flat stars to the corners. Dedicated CMOS and CCD astronomy cameras connect directly via 48mm T-threads; DSLR and mirrorless cameras need a T-ring for your specific mount (sold separately).
Is this OTA only? What else do I need?
Yes — no mount, eyepieces, diagonal, or finder are included. Plan on a 2" star diagonal, a set of eyepieces (a 25mm for wide field, a 10mm for medium power, and a 4–5mm for planetary is a good starting trio), and a finderscope or red dot sight. If you're new to refractors, budget for the complete system. A telescope like the AT115EDT deserves quality accessories to match its optics.
Does it come with a case?
Yes — a soft-sided heavy-duty nylon carry case with paper pockets in the lid and foam cutouts for 7 accessories. The scope travels in one bag.
Optional Accessories
-
Astro-Tech 2" 99% Reflectivity Dielectric Mirror Diagonal — The companion diagonal for this scope. Dielectric coatings reflect more light than standard aluminum, and 2" barrels handle the wider fields of view the AT115EDT can deliver.
-
Astro-Tech 0.8x Reducer/Field Flattener for AT115EDT (Version II) — Drops the focal ratio to f/5.6 and focal length to 644mm for faster, wider-field imaging with flat stars to the corners. Designed specifically for this scope.
-
Astro-Tech 1x Field Flattener for AT115EDT — Full focal length, flat-field imaging at f/7 and 805mm. For when you want the full reach of the telescope with corrected star shapes across the field.
-
Astro-Tech V3 0.8x Reducer/Field Flattener for AT115EDT with 3.2" Focuser — The latest version, optimized for the 3.2" focuser.
-
Astro-Tech V3 1x Field Flattener for AT115EDT with 3.2" Focuser — Full focal length flat field, V3 version for the 3.2" focuser.
Final Thoughts
The AT115EDT is the refractor that Cloudy Nights members call "the telescope that punches way above its price range" — and after 56 reviews averaging 4.9 stars and an 846-reply owners thread that's still active four years in, the consensus is hard to argue with. It's 115mm of triplet APO with a focuser that holds a brick, optics that compare favorably to scopes at significantly higher prices, and a package of features — compression rings, camera angle adjuster, Losmandy dovetail, carry case — that most competitors charge extra for or skip entirely. It won't replace a 10-inch Dob for hunting the faintest deep-sky objects. It will show you planets, the Moon, double stars, and bright deep-sky with a clarity and contrast that no reflector at any price can match. If you've always wanted to know what the refractor fuss is about, this is where you find out.
