The AT70ED delivers genuine ED glass performance at an honest price. Seventy millimeters of aperture at f/6 yields 420mm of focal length — a sweet spot for wide-field deep-sky observing and planetary detail on the Moon. The FK-61 ED glass controls chromatic aberration well for a doublet, and it's compact enough to toss in a backpack and take anywhere. Twenty-three owner reviews, and growing.
There's no fluff here. This is an entry-level ED scope, and we're not pretending it's something it isn't. But entry-level doesn't mean compromise. The focuser is a dual-speed 2-inch Rack and Pinion with 10:1 fine focus — the same mechanical foundation used on much larger AT instruments. The single tube ring mounts to a photo tripod via the 1/4"-20 foot, or accepts a Vixen dovetail plate for more serious mounting systems. The scope accepts 2" and 1.25" eyepieces via brass compression rings.
The AT70ED is a working scope. You'll observe with it, not just admire it. That's the design.
The Optical Design
FK-61 glass is a Schott product — the optical equivalent of the FPL-51 premium ED glass. At f/6, FK-61 delivers very low residual chromatic aberration across the visible spectrum. Bright planets show with minimal false color, and wide-field views on the Moon and deep sky are sharp across the entire field. The multi-coated optics maximize light transmission and contrast — no surprises there.
The f/6 focal ratio is fast enough to gather decent light for deep-sky observation but slow enough that optical aberrations stay controlled without exotic glass. It's a practical ratio, which is why you see it on scopes from 50mm to 150mm across the industry. At 70mm and f/6, you've got 420mm of focal length to work with — enough reach for lunar and planetary detail, but still wide enough that you can frame large objects like the Orion Nebula or the Pleiades in their entirety with a 25mm eyepiece (16.8× magnification, 2.5-degree field).
The coating is standard multi-coated treatment on all air-glass surfaces. It's not fancy, but it's effective. What you see is what you get: a clean, bright image without the optical quirks you'd encounter in uncoated or partially coated designs.
The Focuser
The focuser is a 2-inch dual-speed Rack and Pinion mechanism with 10:1 fine-focus ratio. You get both coarse and fine knobs — the coarse knob for rough focusing, the fine knob when you're dialing in critical focus or tracking an object. Ten-to-one fine focus is smooth enough for planetary observation and precise enough for visual photometry or simple lunar imaging. No camera angle adjuster (CAA) on this model — it's a simple, direct focuser without the mechanical complexity. If rotation matters to you, step up to the AT72EDII or AT80ED.
The focuser accepts 2" and 1.25" eyepieces (or imaging cameras) via brass compression rings. The rings have a slight concave surface that centers the barrel without scratching — standard design, proven over decades. This is reliable, no-fuss interface.
Built for the Field
The AT70ED weighs about 4 pounds without accessories — light enough to carry one-handed but substantial enough that mechanics feel solid. The single mounting ring comes with a foot featuring a 1/4"-20 thread hole. That hole accepts a standard camera tripod head, or a Vixen dovetail plate if you want to mount it on an equatorial or altazimuth head. It's the minimal-complexity approach to mounting: you pay for what you use, and the 1/4"-20 hole is enough for most setups.
What's Included
- Astro-Tech AT70ED 70mm f/6 FK-61 ED refractor OTA
- Single mounting ring with foot and 1/4"-20 thread hole
- 2" and 1.25" brass compression ring eyepiece holders
- Lens cap
Features
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70mm f/6 FK-61 ED doublet — Fully multi-coated. Clean color correction on bright targets and wide-field deep sky.
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420mm focal length — Fast enough for light gathering, slow enough that color correction stays simple.
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Dual-speed 2" Rack and Pinion focuser — 10:1 fine focus ratio. Smooth, reliable, no complexity.
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1/4"-20 tripod mount with single tube ring — Works on any photo tripod. Accepts Vixen dovetail plates for equatorial or altaz mounts.
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Brass compression ring holders — Secure, reliable interface for 2" and 1.25" eyepieces and small cameras.
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Compact and portable — 4 pounds, fit-in-a-backpack size. Grab-and-go observing without sacrifice.
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FK-61 glass — Optical equivalent of premium FPL-51 ED glass. Proven performance on bright targets and deep sky.
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Honest value — Entry-level ED without the entry-level prices you'd find in uncoated or partially-coated scopes.
Under the Night Sky
At 70mm, you're observing at the threshold where aperture starts to matter. The Moon is sharp and detailed — craters, scarps, rilles all stand out in reasonable magnifications (60× to 120× is the sweet spot for lunar work). You can get decent lunar imaging with a small camera and a 2× Barlow if you're careful with atmospheric seeing.
Planetary observing with the AT70ED is real but has limits. Jupiter shows cloud detail and the Great Red Spot under steady seeing. Saturn's rings are clearly separated from the ball, and you can glimpse cloud structure in the atmosphere. Mars, when it's favorably placed, shows polar caps and albedo features — not the level of detail you'd get with 130mm, but honest Mars. Venus shows phases, which is always worth a look. These are not casual glances. These are objects worth spending time on.
Double stars are the AT70ED's playground. At 70mm and f/6, you have enough aperture to resolve pairs down to about 1.5 arcseconds under decent seeing. The Trapezium in Orion separates into distinct stars. Binary star observing is satisfying on this scope — there are thousands of interesting pairs in the sky, and the AT70ED resolves enough of them to keep you busy for years.
Wide-field deep sky is where the AT70ED shines. At 420mm and a reasonable 25mm eyepiece (16.8×, 2.5-degree field), you frame the entire Orion Nebula with room to spare. The Pleiades looks exactly like it should — a cluster of stars in a nice-sized field, not a compressed blob. Messier objects like M13 (Hercules Cluster), M31 (Andromeda), M42 (Orion Nebula), and M57 (Ring Nebula) all look their best in a scope of this size — enough magnification to resolve structure, wide enough field that you're not staring at a postage stamp.
Light pollution limits any scope, but 70mm handles moderately light-polluted skies well. You won't do deep-sky work under urban lights, but from a backyard 30 minutes outside the city, or a dark site, the AT70ED will show you why you got into this hobby.
Community Says
"This is a solid little scope for the money. Sharp optics, good focuser, and light enough to take anywhere. I use it on a photo tripod for quick looks and on an equatorial head for imaging. Does both well."
Observing Tip
The AT70ED benefits from a proper finder scope or red-dot finder. At 70mm and 420mm focal length, your field of view at typical magnifications is manageable but not huge. A red-dot finder like the ATF850SI or a small crosshair finder will save you time hunting for objects. Centering an object in the field first with a finder, then acquiring it in your eyepiece, is faster and more satisfying than star-hopping blind. If you're starting from scratch, budget for a finder scope in addition to your eyepieces.
Frequently Asked Questions
How does the AT70ED compare to the AT72EDII?
Glass, focuser, and mounting differ. The AT72EDII uses FPL-53 glass (premium) with a camera angle adjuster on the focuser and a Vixen dovetail with two tube rings. The AT70ED uses FK-61 glass (entry-level ED), a simple dual-speed focuser without CAA, and a single mounting ring with a 1/4"-20 foot. The AT72EDII is more capable as an imaging platform and has better color correction. The AT70ED is lighter, more portable, and cheaper. Both are good scopes. The AT72EDII is the premium version.
Can I use the AT70ED for astrophotography?
Yes, but with caveats. The 1/4"-20 mounting is fine for small mirrorless cameras or planetary cameras on a solid tripod head. At 420mm f/6, the AT70ED is a wide-field imager. Pair it with a small chip camera for deep-sky work — galaxies, nebulae, open clusters all fit nicely at native focal length. There's no dedicated reducer or flattener for this model, so you're working at native focal length and focal ratio. This is straightforward wide-field imaging work, not planetary or planetary nebula work.
What mount does the AT70ED need?
For visual use, any decent photo tripod with a standard ball head will work — nothing fancy required. For short imaging sessions, a tripod works too. For tracking-based astrophotography (say, a 30-second planetary video or a 5-minute deep-sky image), you need an equatorial mount capable of precise tracking. At 4 pounds, the scope fits on most mid-range equatorial mounts. A Vixen dovetail plate ($20–40) lets you mount the scope on any head with a Vixen-style saddle. No exotic mount required.
Can I mount this on a camera tripod?
Yes — directly. The 1/4"-20 foot threads into any standard photo tripod head. The scope is light enough that a decent ball head or pan-tilt head handles it without strain. For visual use, this is a fine setup. For long-duration imaging, an equatorial mount or alt-azimuth head with tracking capability is better, but a tripod works for quick looks or short camera exposures.
What do I need to start observing with the AT70ED?
The scope itself, a tripod (or mount head), eyepieces, and a diagonal. The AT70ED accepts standard 2" and 1.25" diagonals and eyepieces. Start with one good eyepiece — a 25mm gives you 16.8× and a nice wide field for deep sky. Add a 9mm or 10mm for 46× to 47× for brighter planetary and lunar work. A 2× Barlow doubles your magnification options. A finder scope or red-dot finder makes acquisition much easier. These are all available separately — nothing locked into Astro-Tech proprietary designs.
Is the AT70ED good as a travel scope?
Absolutely. Four pounds, 18 inches long if you include the mounting ring, and simple mechanics make it ideal for travel. The 1/4"-20 foot threads into any tripod head you can fit in a travel bag. A small ball head, a couple of eyepieces, and a diagonal fit easily in a carry-on. The scope will survive transport, cool down fast at a new observing site, and perform the same way it does at home. This is a genuine grab-and-go scope.
Optional Accessories
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Vixen Dovetail Plate (ATVUP9) — Mounts the AT70ED on equatorial or altaz heads. Recommended if you move beyond photo tripod use.
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Finder Scope (ATF850SI 8×50) — Makes object acquisition faster and more reliable. Improves the observing experience significantly.
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2× Telecentric Barlow (AT2XTB) — Doubles your eyepiece magnification options. Useful for lunar and planetary work.
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Standard Eyepieces — Start with a 25mm wide-field eyepiece for deep sky (16.8×), then add a 9mm or 10mm for higher magnification (46–47×). AT or third-party eyepieces both work.
Final Thoughts
The AT70ED is an entry-level ED refractor that doesn't pretend to be something it isn't. It has FK-61 glass, not FPL-53 or FCD-100. It has a simple focuser without a camera angle adjuster. It mounts on a photo tripod with a 1/4"-20 foot. These are practical choices that keep the price low without sacrificing optics or mechanics. You get genuine ED performance in a package you can carry, afford, and actually use without overthinking it. Wide-field deep sky, lunar detail, planetary observing, double stars — the AT70ED does all of these well enough to spend real time with the scope. That's what matters.
