The Orion ED80 is an 80mm (3.1”) ED doublet refractor with a focal ratio of f/7.5 and a focal length of 600mm. It uses the same optics as the Sky-Watcher Evostar 80ED (formerly ProEd 80). The ED80 has a relatively simple apochromatic doublet design, with an FPL-53 lens element. This design is pretty much the gold standard for most inexpensive ED doublets. Pricier scopes will either use fluorite in place of the FPL-53, or add an additional lens element—either will provide better color correction, and the latter can improve edge-of-field aberration control, which is crucial for astrophotography. But the ED80’s design works just fine, and there’s not much chromatic aberration. Compared to a cheap FPL-51 or FK-61 triplet or doublet, the ED80 is vastly superior optically.
The ED80’s slower focal ratio of f/7.5 may not make it quite as suitable for wide-field views or imaging, but at the same time it has much sharper high-power images, doesn’t need super-short focal length eyepieces or a Barlow for high magnification use, and the reduced chromatic aberration means less bloat on your stars in images. Additionally, the longer focal length allows you to do a little better imaging of small objects like globular clusters and galaxies (though they’re still not ideal targets for a small refractor).
The ED80’s focuser is a relatively proletarian single-speed 2” Crayford. It uses a simple set screw to hold your diagonal/adapter and is, of course, all-metal; the lack of fine adjustment or easy locking/tension adjustment makes it far from ideal for imaging purposes, but it will suffice for a simple DSLR/mirrorless camera or diagonal and eyepiece combination. The focuser also has a Vixen/Synta-style shoe molded-in for a finderscope/red dot sight to be attached.
The ED80 comes with a simple foot on the bottom with a ¼ 20 hole for use on a photo tripod, which is fine for birding or casual astronomy use. However, for almost anything else, you’ll want to buy Orion’s 100mm ID tube rings and a compatible Vixen-style dovetail plate, which will allow you to put the ED80 on almost any mount you could possibly want.
For visual use, we would choose a lightweight alt-azimuth mount for the ED80 like the Vixen Porta II or the Explore Scientific Twilight I. An equatorial mount is really only necessary for astrophotography with the ED80 and can easily double or triple the weight of the whole setup.
For astrophotography, you’ll of course want a computerized German equatorial mount with autoguider compatibility. Orion sells this scope bundled with their Sirius HEQ5, and this is really the best choice all around (Sky-Watcher’s HEQ5 Pro is identical apart from the fit and finish). Celestron’s Advanced VX will work too if that’s all you can afford, but its tracking accuracy is inferior, and you will rely more on autoguiding to pick up the slack, which kind of ruins the cost savings.
Should I buy a Used Orion ED80?
It is unlikely to encounter any substantial issues with the ED80 when buying a second-hand unit, and anything wrong will be immediately apparent, such as damage to the objective lens or focuser, as this telescope is so straightforward in design. A used ED80 might make sense to buy where a new one doesn’t; e.g. equipping it with tube rings and a dual-speed focuser may be more economical than buying a new equivalent scope if the seller does not already have such things supplied.
Aftermarket Accessory Recommendations
For visual use, a field flattener is not needed, but for astrophotography, a field flattener or combination reducer-flattener, such as Orion’s 0.85x unit, is a must-have for the ED80. Almost any eyepiece will work well with this telescope at f/7.5, such as a set of “redline” or “goldline” eyepieces, though we’d definitely recommend a 2” star diagonal such as the Apertura 2” Twist Lock Dielectric unit and a wide-angle 2” eyepiece. The Apertura 38mm SWA (16x) will provide the maximum possible field of view with the ED80 – about 4.5 degrees, or nine times the apparent diameter of the full Moon in the sky – allowing you to see even the largest deep-sky objects like the Hyades or the Sagittarius Star Cloud in one field of view with ease. Additionally, a UHC nebula filter such as the Orion UltraBlock filter will help bring out objects like the Veil Nebula under dark skies and improve views of brighter emission nebulae like Orion from light-polluted locales.
You’ll also want Orion’s 100mm tube rings, a Vixen or Losmandy-style dovetail plate for attaching the ED80 to a mount, and some kind of red dot finder for visual use (or a guide scope for astrophotography).
With 600mm of focal length, the Orion ED80 is best for wide-field imaging of nebulae and open clusters. However, you can get surprisingly good images of globular clusters as well as bright galaxies like M51 with the ED80, the latter provided you can get good integration time/signal-to-noise ratio to reduce noise as much as possible.
On most EQ5 and EQ6-class mounts, you can get away with exposures between 30 and 60 seconds unguided with the ED80 and a DSLR. Guiding is of course necessary for longer exposures.
For guiding, we would recommend just taking advantage of the ED80’s built-in shoe and just putting a 30mm or 50mm guide scope in. A dual-scope style mounting plate and larger guide scope are overkill, and the hypothetical increase in guiding accuracy is probably going to be offset by the increased strain you’re putting on the mount, in addition to the high cost of obtaining said hardware.
For obtaining satisfactory images of planets with the Orion ED80, a 3x Barlow lens and suitable planetary camera setup may be used. However, due to the limited resolving power of an 80mm instrument, it is preferable to opt for a larger telescope for this task, usually a catadioptric or Newtonian of 8” or greater aperture.
What can you see?
The Orion ED80 offers a wide field of view with its 600mm focal length paired with a quality 2” diagonal and wide-angle eyepiece. Deep-sky views are similar to a small 100mm or 114mm reflector, though you don’t get diffraction spikes on stars – which helps with splitting the countless doubles that can be observed with this telescope. Open star clusters like M35, the Pleiades (M45), and others appear stunning in the ED80. Unfortunately, globular star clusters and planetary nebulae tend to be featureless smudges that require larger instruments to resolve; 80mm of aperture is simply not able to gather enough light even with the unobstructed high-contrast performance of a good ED refractor. Bright emission nebulae like Orion (M42) and the Lagoon (M8) look great in the ED80, particularly so with dark skies and/or a UHC filter – while fainter and very large nebulae like the North America Nebula will need both dark skies and a filter to be visible at all. Galaxies are mostly detail-less smudges—or groups of them—with only an 80mm aperture, though hints of dust lanes in the brightest Messier catalog galaxies may just barely be glimpsed under optimal conditions with the ED80.
The ED80 is great for viewing the Moon and planets in spite of its small aperture, with the ED glass objective delivering sharp views with fairly little chromatic aberration. The phases of Mercury and Venus are clearly visible, as are the polar ice caps on Mars and possibly a few surface features under ideal conditions. The Moon looks stunning, and Jupiter’s four Galilean moons are of course easy to see at low power. Jupiter’s equatorial cloud bands, the Great Red Spot, and other atmospheric details look stunning. Saturn’s rings and the Cassini Division in them, along with some of the ringed planet’s moons, can also be seen. However, a larger telescope is needed to see the Galilean moons’ disks and shadows or reveal all of Saturn’s moons. Uranus and Neptune appear as fuzzy blue dots, requiring more aperture than the ED80 possesses to clearly resolve or see their moons, and Pluto is also too dim to see with only 80mm of aperture.