Refractors are popular telescopes, with lower maintenance and less cool-down time compared to reflectors. Their clear apertures also provide high-contrast views, especially when they are made with extra-low dispersion (ED) glass. But in apertures greater than 100mm they can be expensive.
The 80mm refractor is a good in-between size. It will work well on the moon and provide decent planetary views.
So, what can you see through an 80mm refractor?
Moon
80mm is enough to show exquisite lunar detail. Countless craters, mountain ranges, smooth volcanic plains: all of these are easy.
During full or gibbous phases, look for debris rays around large craters like Tycho. Using a short focal length eyepiece, and/or a barlow lens, (this one from Orion is a good choice) look for finer detail such as craterlets around Copernicus.
The lunar surface changes day by day and even hour by hour, as it gradually moves through its phases.
These cell phone captures show some of the lunar detail visible through my 80mm apochromatic triplet. An achromat would show some false color.
Planets
The planets of our solar system are small targets, better suited for larger-aperture instruments. Nevertheless, an 80mm refractor will easily show Jupiter’s four Galilean moons and two equatorial bands.
If you time it right, you might glimpse the Great Red Spot: Jupiter rotates on its axis every ten hours, so if you miss the GRS, you can always wait a while then try again.
On nights of steady seeing, you might even catch a shadow transit! Use as much magnification as conditions will permit.
Saturn is always a treat, even in a small telescope. At low or medium power, you can easily discern its rings.
At high magnification, you might notice the Cassini Division within the rings, though this is difficult with less than 100mm aperture and requires very good seeing.
Mars and Venus each go through phases which see them increasing or diminishing in size.
At its close approaches, Mars will show some dark shading on its surface, hinting at surface details. Venus is best during its crescent phase, appearing as a brilliant, featureless mini-moon.
Star and clusters
One of my favorite things to do with my 80mm refractor is mount it on an AZ4, put in a wide-angle eyepiece, and simply pan around the Milky Way, taking in the view. At f/6, an 80mm refractor offers a very wide field of view: a 19mm Panoptic, for example, yields 25x power with a 2.7-degree field of view, while a 27mm Panoptic puts you close to binocular territory in terms of angular field.
This article explains high quality and wide angle eyepieces if you would like more information about when to upgrade your eyepieces.
With no pressure to find a certain object, I like to roam around and take note of interesting asterisms and binary stars. You might even stumble on a cluster or nebula by accident, checking your smartphone app or star charts to see what you’ve caught.
Open clusters make ideal targets for small refractors. Sprawling clusters like the Pleiades and Beehive, for instance, favor the wide views from a telescope like the Orion ST80 (Affiliate link).
More compact clusters like M11 and M35 are still enjoyable but it will be more difficult to resolve stars in these compact clusters.
Globular clusters are also within reach of an 80mm refractor, but don’t expect to resolve many stars in those fuzzy gray balls.
Open clusters M37 and M11 shot through my 80mm refractor. Note than the image scale will be different depending on the eyepiece you use.
Nebulae
This is a broad category, comprising small, compact targets like M57, to huge, extended objects like NGC7000.
An 80mm refractor won’t show you anything close to the detail you see in photographs, but from a dark site there is still a lot to see.
The Orion Nebula, M42, appears as a ghostly green-grey flower through an 80mm, and is impressive at any magnification. A short-tube refractor like the ST80 can easily see the entire North America Nebula, an impossible feat with an 8-inch Dobsonian (a highly recommended beginner telescope, read our recommendations in the linked article). From dark skies, I was able to fit both the Lagoon and Trifid nebulas into the same field of view, but this will require a 2-inch eyepiece and less expensive models may not be able to accommodate these.
A long refractor with an EQ or auto-tracking mount would be more suitable for viewing targets such as the Ring and Dumbbell Nebula.
These can be enhanced with an OIII or UHC filter. These are available from High Point Scientific, Corey uses the linked filters.
Galaxies
Even distant galaxies are not out of range of an 80mm refractor, if you pick the right ones. M31, the Andromeda Galaxy, is huge and requires a very wide field of view.
Though 80mm is too small to see much detail, the bright core is a splendid sight and under dark skies you can start to detect the spiral arms and dark dust lanes so prominent in photographs, as well as its nearby companion galaxies.
Again, this is not possible with a more traditional deep-sky telescope like a large Dobsonian.
Another worthy target is M33, the Triangulum Galaxy. This galaxy is large and diffuse, meaning its light is spread over a large area.
My wide-field refractor picks it up well, showing as a broad, hazy patch against a dark sky. With galaxies, it is often an achievement just to see them at all.
Things to consider
The hobby of amateur astronomy is about getting under the stars and engaging with the universe on a personal level, using just a few pieces of glass.
No algorithms, no microprocessors, no editing software.
A small telescope like an 80mm refractor has its place just as much as a 16” Dobsonian and can do things the larger telescope can’t. Also, you can be set up an observing in minutes.
Even if you already own a larger telescope, an 80mm refractor is a worthwhile investment.
But what about deep-sky objects?
Though small refractors are not usually recommended for DSO viewing, if you set your expectations accordingly you can have a lot of fun viewing star clusters and nebulae with these telescopes.
But before we get to all that, let’s go over a few criteria for selecting an 80mm refractor.
How to Select an 80mm Refractor
Focal Length
What you can see with your telescope will depend a lot on its focal length. If you’re mainly interested in lunar and planetary viewing, look for something with at least 800mm focal length (f/10).
Note that longer focal lengths require a stable mount to minimize vibrations. Indeed, this is why so many beginner telescopes are difficult to use.
If your interest lies more in sweeping the expanse of the Milky Way searching for faint fuzzies, a focal length of 480mm (f/6) or less is ideal.
Type of Mount
The effectiveness of any telescope is limited by the quality of the mount.
For planetary viewing, many prefer equatorial (EQ) mounts with their smooth tracking. An altazimuth (AZ) with slow-motion controls would also work.
I wouldn’t recommend anything lighter than an EQ3 or AZ3.
With shorter focal lengths, slow-motion tracking isn’t necessary, and a mid-duty altazimuth mount like an AZ4 works well.
A Go-To AZ mount like the Celestron NexStar is also worth considering if you would prefer automatic tracking.
Type of glass
The view through your refractor will depend a lot on the quality of the objective lens.
This is especially true for short-focus refractors below f/6, where false color becomes increasingly apparent.
An objective using ED glass, especially a triplet, will improve your views dramatically but at a dramatic increase in price.
