Product Description
This Astro-Tech AT70ED refractor has:
• 70mm f/6 fully multicoated doublet optics using FK-61 ED glass
• dual-speed 2" Rack and Pinion focuser
• 2" and 1.25" brass compression ring eyepiece holders
• Single ring with a foot that has a 1/4" 20 thread hole for easy attachment to a dovetail.
Length: 11.8" dewshield retracted
Weight: 4lbs 13.6 oz with the ring
The AT70ED is bringing ED optics to you at a fantastic price. You get a 2" Rack and Pinion focuser with a microfine 11:1 fine-focusing ratio finished in our Aston Martin Grey trim. You get a single ring with a built in foot. The foot has a 1/4" 20 thread hole for easy attachment to a photo tripod or a dovetail of your choice. The finely-machined Astro-Tech AT70ED comes with both 2" and 1.25" eyepiece holders using non-marring brass compression rings that won’t scratch your star diagonal or eyepiece barrels. The AT70ED also comes with a retractable dew shield to make it as compact as possible at a tad under one foot.
As with all Astro-Tech scopes, the AT70ED gives you fully-multicoated ED optics that are essentially free of the annoying halo of unfocused violet light (chromatic aberration) that mars the bright-object images of lesser scopes, despite the fast focal ratio, and even at very high magnifications.
Features of this Telescope . . .
• ED doublet refractor optics: 70mm (2.8") aperture, 420mm focal length, f/6 focal ratio doublet optical system using an FK-61 ED (Extra-low Dispersion glass) element to reduce spurious color halos and fringing to vanishingly low levels.
• Fully multicoated optics: The AT70ED objective lens has the latest state-of-the-art antireflection multicoatings on all air-to-glass surfaces for high light transmission and excellent contrast. This can easily be seen by looking into the objective lens of the scope. Virtually no reflection of your face will be seen. It’s a sure sign that the high transmission coatings are doing their job, by letting virtually all the light enter the scope, rather than reflecting some light back to your eye.
• Dew shield: A retractable dew shield slows the formation of dew on the lens in cold weather to extend your undisturbed observing time. It also improves the contrast, similar the lens shade on a camera lens, when observing during the day or when there is excessive ambient light at night, such as a neighbor’s backyard security light. A slip-on metal dust cap for the dew shield is standard.
• 2" Rack and Pinion dual-speed focuser: The precision-made no-backlash dual speed 2" rack and pinion focuser is based off our EDT line of telescopes. Very smooth, and very robust. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with an 11:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during high magnification visual observing and critical 35mm or CCD imaging. The focus knobs have ribbed gripping surfaces so they are easy to operate, even while wearing gloves or mittens in cold weather.
• Long focuser travel: The long 92mm (3.62") travel of the focuser drawtube helps keep the overall scope length reasonable for convenient travel and storage. The long drawtube length also permits switching between visual or photographic use with no add-on extension tubes needed. The drawtube has a scale marked in 1mm increments so you can note individual focuser positions for easy return to the correct focus when switching between visual use and photography. A drawtube lock knob underneath the focuser lets you lock in your photographic focus.
• Compression ring eyepiece holders: The focuser’s drawtube terminates in a 2" eyepiece holder that uses a non-marring soft brass compression ring to hold a 2" star diagonal and/or accessories in place. The compression ring won’t scratch the barrel of your star diagonal and accessories as an ordinary thumbscrew can.
A supplied 1.25" accessory adapter slips into the 2" eyepiece holder to let you use a 1.25" star diagonal, image erecting diagonal, or photographic accessories. Like the 2" eyepiece holder, the 1.25" adapter also uses a non-marring soft brass compression ring to hold 1.25" star diagonals and accessories in place. If you are partial to 1.25" eyepieces and need an outstanding diagonal for this scope, consider the 99% reflectivity Astro-Tech 1.25" dielectric diagonal #AT1D. It's a Sky & Telescope Hot Product for 2007. An optional Astro-Tech 2" dielectric star diagonal #AT2D will give you the same 99% reflectivity performance with 2" eyepieces.
• Tube finish: The optical tube and lens shade are finished in a white powder coat while he focuser and trim are Aston Martin Grey anodized.
The AT70ED comes in a 16" x 9.5" x 7" padded cordura nylon case to help keep your scope nice and safe.
Tech Details
| Aperture | 70mm |
|---|---|
| Focal Length | 420mm |
| Focal Ratio | f/6 |
| Heaviest Single Component | 4 lbs 13 ounces |
| Optical Coatings | Multi-coated |
| Supplied Eyepiece | None |
| Telescope Type | Refractor |
| View Finder | None |
| Warranty | 1 year |
Reviews
1. To rotate the foot for side mounting you have to completely un-hinge the ring, and then reposition the foot as desired, then close the ring and retighten the screw.
2. The telescope is very hard to balance. After attaching a 5 inch vixen style dovetail to the foot and attempting to use it side mounted, you just could not slide the scope forward far enough to balance a 2 inch diagonal + eyepiece. You cannot just use a longer dovetail because it would interfere with the two speed focusing knobs. I had to construct a counterbalance that weighs 2lb. 2oz. and rides forward of the dovetail to balance the telescope in a side mounted position. This makes the whole package hanging on the mount just break 8 lbs.
Optically nothing exciting to report, and that is as it should be. Nice wide field with pinpoint stars to the limit of the eyepiece. The instructions included with the telescope state the maximum practical magnification is 138x. I have tried it with a 6mm wide angle 68 degree eyepiece for 70x with excellent results, then used AT's Telecentric 2X for 140x which resolved Jupiter and Saturn to the limit of that night's seeing, which was very steady indeed.
I know it sounds like I'm nitpicking , after all, this is only $329! which is an amazing low price for a telescope built like this, the focuser alone is a work of art.
I am a visual observer only so cannot give any opinion about it's suitability for AP. (Posted on 12/6/2023)
The build quality is amazing, it has a good amount of structure which is mostly (if not all) metal. I doubt it would break if I dropped it, though I am not sure I want to test this durability. Even though the mounting plate is more of a mounting shoe, it is solid and seems to attach well to the makeshift plate I fashioned. 5/5.
The focuser is great; I would explain it as a 2-speed pinion. I can see no reason it would need to be upgraded at any point in the scope's life. It also accounts for 2/3 the scope's weight. It may be difficult for some eyepieces to come to focus without a diagonal, but this is a feature of every refractor I have used so far. I doubt it would be possible to put a focuser with more focus travel on this scope – it would either cause vignetting or impact the lens cell. I could see someone buying this scope for the focuser alone… 5/5.
Image quality I will divide into 2 parts - high-resolution (i.e. star test) and general-purpose (Jupiter, Saturn, star clusters, and terrestrial viewing).
For general-purpose viewing, this scope is very good. The stars are pinpoints, and even zooming in to see more (80-100x) remains, for the most part, fairly sharp. Star clusters such as the Pleiades look amazing at night, as does the landscape surrounding my home during the day. It is difficult to see any chromatic aberration below 80x zoom, and when it was visible it is not particularly obvious – CA is dimmer for this scope than a 100mm f10 achromat I looked through at similar power, and when used terrestrially, I have not noticed it. There is some field curvature, though that seems to be the nature of short focal-length refractors. The two main cloud bands (and hints of a third, fourth, and fifth) were visible on Jupiter, and Saturn was crisp to observe – though I could not quite make out the Cassini division (this may be due to aperture and seeing limits). 4.5/5.
For high-resolution viewing, the scope has a couple minor issues. Mine is not in perfect collimation (one side of the defraction rings is slightly brighter than the other) and shows slightly pinched optics (defraction rings hint at a triangular shape). This would not be an issue if it were easy to adjust collimation, but on this scope it is not a simple task. Astronomics offered to change out the lens cell, though I have not decided whether to have that done as of this writing. These issues may not be present in other samples of this scope, and they mostly affect the maximum performance of this scope. Unless I am trying to split a double star I do not notice them. 3.5/5.
Overall optical quality 4/5.
Overall I am pleased with this scope and would likely buy it again. The optical quality is good, but the difficulty in tuning it makes this a 4/5 instead of 5/5. It is a step up from the entry level wide-field achromats (e.g. ST80) and makes a good travel scope, especially since it costs 30% less than other ED scopes its size.
(Posted on 11/23/2022)
Just recently I've started using it for solar observation using a Herschel wedge with very pleasing results.
The AT70ED is an excellent first refractor. It's inexpensive (yes there are cheaper refractors but not with these optics and build quality) and the quality is so high that it will be a first scope that will stay with you for a long time. I now own a Takahashi refractor but I will never be parted from my AT70ED. (Posted on 9/14/2022)
I also own the Astro-Tech 50mm right angle finderscope and this has an outstanding optic, finish and mechanicals as well.
Great quality, superb function, appearance and price.
Thanks Again, Astronomics...
(Posted on 12/8/2021)
I just got my new AT-70ED ($299.00)from Astronomics today. My intention was to use my Nexstar 6SE GOTO mount and tripod to mount the OTA and start doing some simple astro photography with it. To this end, I have also ordered a ZWO ASI224CS camera for it. My main intention for the scope is AP or EAA and not much visual astronomy use since it is a small aperture scope.
The scope arrived on time from FEDEX Home Delivery in excellent shape. I ship a lot of heavy and pricey items so I was impressed to see the little scope was triple boxed. Great Job Astronomics! I opened the boxes to get a look at it and discovered that it looked exactly like in the online store photos...no surprises there.
I took the scope out and attempted to mount it to the Nexstar 6SE mount I have but it would not seat and tighten up properly in the dovetail clamp. A little visual checking and I decided to attempt to attach the original OTA bracket to a heavy 8” dovetail I had laying around. At first I used the 1/4-20 bolts I had which were hex head. It bolted up fine but the hex heads caused interference in the mount clamp so I decided to get a set of 1/4-20 Allen wrench bolts with smaller and rounded heads. These use a 5/32 Allen wrench to tighten. This solved the problem right away and now the OTA clamps right up to the Nexstar mount without any problems.
Once I got the OTA mounted, I also added a 6x30 finder scope to the accy bracket provided on the top of the OTA. I went outside and set the scope up for a test and align the finder. I popped in a 20mm WA eyepiece and removed all the OTA and finder scope caps so I could see thru it. I focused in on a bird house out in my side yard and I was happily impressed with the view. It was the clearest view I have ever had of that bird house from my drive way. I have had all kinds of scopes here mostly CATS and NEWTS but none of them produced a tack sharp view as well as this little 70ED. Then I tried my Celestron 8-24 Zoom eyepiece to see how well the image held up under more power. It remained sharp all the way up to the 8mm setting, albeit somewhat dimmer. I should say, I am not a refractor person. That is I have had some APO’s before 80 and 100mm, but just for a very short time. I never gave them a chance to satisfy me. They just seemed too small to be of any visual use to me. But now, since my plans are for mostly AP, I can see how this will fit in my routine such as it is and provide some quick grab and go visual use also. As a matter of fact, I may save up and get the AT-102ED version in the future. I will also probably have to get a heavier mount probably a GOTO GEM in the future also. Time will tell if all this takes place or not. Will attempt to use it out at night ASAP especially when the camera arrives.
All in all, seems like a very nice OTA for the money. Time will tell.
Tom H (Posted on 6/24/2021)
I just got my new AT-70ED ($299.00)from Astronomics today. My intention was to use my Nexstar 6SE GOTO mount and tripod to mount the OTA and start doing some simple astro photography with it. To this end, I have also ordered a ZWO ASI224CS camera for it. My main intention for the scope is AP or EAA and not much visual astronomy use since it is a small aperture scope.
The scope arrived on time from FEDEX Home Delivery in excellent shape. I ship a lot of heavy and pricey items so I was impressed to see the little scope was triple boxed. Great Job Astronomics! I opened the boxes to get a look at it and discovered that it looked exactly like in the online store photos...no surprises there.
I took the scope out and attempted to mount it to the Nexstar 6SE mount I have but it would not seat and tighten up properly in the dovetail clamp. A little visual checking and I decided to attempt to attach the original OTA bracket to a heavy 8” dovetail I had laying around. At first I used the 1/4-20 bolts I had which were hex head. It bolted up fine but the hex heads caused interference in the mount clamp so I decided to get a set of 1/4-20 Allen wrench bolts with smaller and rounded heads. These use a 5/32 Allen wrench to tighten. This solved the problem right away and now the OTA clamps right up to the Nexstar mount without any problems.
Once I got the OTA mounted, I also added a 6x30 finder scope to the accy bracket provided on the top of the OTA. I went outside and set the scope up for a test and align the finder. I popped in a 20mm WA eyepiece and removed all the OTA and finder scope caps so I could see thru it. I focused in on a bird house out in my side yard and I was happily impressed with the view. It was the clearest view I have ever had of that bird house from my drive way. I have had all kinds of scopes here mostly CATS and NEWTS but none of them produced a tack sharp view as well as this little 70ED. Then I tried my Celestron 8-24 Zoom eyepiece to see how well the image held up under more power. It remained sharp all the way up to the 8mm setting, albeit somewhat dimmer. I should say, I am not a refractor person. That is I have had some APO’s before 80 and 100mm, but just for a very short time. I never gave them a chance to satisfy me. They just seemed too small to be of any visual use to me. But now, since my plans are for mostly AP, I can see how this will fit in my routine such as it is and provide some quick grab and go visual use also. As a matter of fact, I may save up and get the AT-102ED version in the future. I will also probably have to get a heavier mount probably a GOTO GEM in the future also. Time will tell if all this takes place or not. Will attempt to use it out at night ASAP especially when the camera arrives.
All in all, seems like a very nice OTA for the money. Time will tell. (Posted on 6/24/2021)
