Smart telescopes and EAA: what each model shows, computed

A smart telescope is a small refractor, a camera and a go-to mount run from a phone

Every smart telescope combines the same parts in one sealed unit:

• a short refractor, 30 mm to 152 mm across, with a fixed camera where the eyepiece would be;
• a computerized altitude-azimuth mount that points and tracks;
• plate solving: the telescope photographs the sky, matches the star pattern against a catalog and works out exactly where it is pointing, so no alignment is needed;
• live stacking: it takes exposures of 10 to 30 seconds, aligns them and adds them together, so the image on your phone gets cleaner and deeper as the minutes pass.

Electronically assisted astronomy (EAA) is the same idea built from separate parts: a regular telescope, an astronomy camera and live-stacking software such as ZWO's ASIAIR, SharpCap, N.I.N.A. or Siril's live stacking. It costs more and takes more setup, but it works with any aperture and focal length.

Current smart telescopes compared: the field of view ranges from 4° to under a degree

Prices are typical US prices checked in November 2026. Pixel scale is how much sky one pixel covers, in arcseconds; smaller means finer detail but a smaller field. Unistellar does not publish its sensors, so its fields and pixel scales (marked *) are worked out from the published field width and megapixel count, assuming a 4:3 sensor.

Above this range, Vaonis's Hyperia is a Canon-built observatory-class smart telescope at about $99,000. Prices change often, and US prices moved with 2025 tariffs.

China's ZWO (Seestar) and Dwarflab lead the budget end; France's Vaonis and Unistellar and the Synta-owned Celestron make the larger and more expensive models. See who makes which telescope.

Planets: Jupiter spans only 12 to 54 pixels in a smart telescope

Planets need focal length, and smart telescopes have very little. At opposition Jupiter is about 46 arcseconds across. Divided by each model's pixel scale, that gives the width of Jupiter in pixels:

At 12 to 20 pixels, Jupiter shows its two main belts and the four Galilean moons, and Saturn shows its rings, but no more. For planetary detail, an 8-inch telescope with a planetary camera gives 8 to 25 times the size (see astrophotography and what each telescope shows on the planets). The Moon, half a degree across, fits every model and fills the narrower ones; it is the best showpiece any smart telescope has. Every model can image the Sun safely only with its solar filter fitted over the front (see solar filters).

The Milky Way: the widest models frame its star clouds, but a camera lens frames the band

The Seestar S30 Pro's 3.99° x 2.24° field holds the Small Sagittarius Star Cloud (M24) or the Lagoon Nebula (M8) in one frame, and so does the Dwarf 3's 2.93° x 1.65° field. The Milky Way's bright core spans more than 30°, so the band itself needs a wide-angle camera. The Seestar S30 Pro and S50 Pro carry a second, 63° wide-angle camera for that, and the Dwarf 3 has one too. Under a bright suburban sky the Milky Way is invisible to the eye and faint even in stacked images; it needs a site of Bortle 4 or darker (see Milky Way observing).

Galaxies: nearly every Messier object fits every frame, but small galaxies stay small

The table counts, for each model, how many of the 110 Messier and 109 Caldwell objects fit inside the frame, and how many also fill at least a quarter of its short side, so they are big enough to show structure. The last five columns give the number of panels needed to cover the largest objects; one panel means it fits in a single frame.

The pattern is a trade. The widest models frame almost everything but leave small galaxies such as M51 and M104 tiny; the Unistellar models and the Celestron Origin Mark II enlarge them but need mosaics of 5 to 12 panels for M31 and the Pleiades. Galaxies also suffer most from light pollution (below), so for galaxies a smart telescope still wants a dark site, the same as any telescope.

Light pollution: a duo-band filter lets a city sky work on emission nebulae, not galaxies

When the sky glow is brighter than the target, the noise in a stacked image comes from the sky, and signal-to-noise grows only with the square root of exposure time. To match a dark-site image, exposure must therefore grow in proportion to the sky's brightness. Sky brightness is measured in magnitudes per square arcsecond (the Bortle scale page gives the values); each 1 magnitude is 2.5 times brighter.

A duo-band filter, built into the Seestar, Dwarf 3 and Draco, passes only two narrow bands around hydrogen-alpha (656.3 nm) and oxygen III (500.7 nm), about 50 nm in total against about 300 nm of visible light. It blocks roughly five-sixths of the sky glow but keeps most of an emission nebula's light. A galaxy's light is starlight spread across the spectrum, so the filter cuts the galaxy as much as the sky and gains nothing.

Exposure is relative to a broadband image from a Bortle 2 site. The duo-band column assumes the filter keeps 90% of the nebula's line light and the sky glow is spread evenly across the spectrum, as modern LED light pollution roughly is.

So an hour on a galaxy from a dark site takes about 36 hours from a city, which in practice means it cannot be done. An hour on the Orion Nebula or the North America Nebula from a dark site takes about 7 hours from a city with a duo-band filter, which is a long but workable night. Find a darker site in dark sky places.

Constellations are too big for any smart telescope's main camera

Orion spans about 20° by 30°. Covering it with the Seestar S30 Pro's 3.99° x 2.24° field would take about 90 panels, and with the eVscope 2 well over a thousand. The 63° wide-angle cameras on the Seestar S30 Pro and S50 Pro, and the Dwarf 3's wide-angle camera, frame whole constellations instead. See the constellations.

Citizen science: smart telescope owners help confirm exoplanets and time asteroid occultations

Unistellar runs the largest smart-telescope science network. In 2025 its owners logged more than 15,000 observations, including 1,465 of exoplanet transits by 146 observers, 417 asteroid occultations by 95 observers and 2,826 comet observations, 480 of them of the interstellar comet 3I/ATLAS. Twenty-four Unistellar observers from seven countries are co-authors on the confirmation of the exoplanet TOI-4465 b.

The AAVSO (American Association of Variable Star Observers) has a Smart Telescope Working Group testing whether smart-telescope images are accurate enough for its variable-star database. It reports that the Seestar S50 can measure brightness to better than 0.02 magnitude, and it is building tools to turn smart-telescope images into usable measurements. See citizen science.

Which smart telescope for which observer

• First telescope, any budget: Seestar S30 Pro or Dwarf 3. Both carry in one hand, frame the big nebulae and M31, and have duo-band filters for city skies.
• Travel: Dwarf Mini or Dwarf 3, at 0.85 kg and 1.3 kg.
• City dwellers: any model with a built-in duo-band filter (Seestar, Dwarf 3, Draco), aimed at emission nebulae.
• More detail on galaxies: Seestar S50 Pro, Dwarflab Draco or Celestron Origin Mark II, ideally from a dark site.
• Outreach and groups: Unistellar Odyssey Pro or eVscope 2, whose electronic eyepiece lets people look through the telescope.
• Citizen science: a Unistellar for its organized campaigns, or a Seestar S50 Pro for AAVSO photometry.

Choose a regular telescope instead if you want to see the sky with your own eyes or want planetary detail (see choosing a telescope). Choose an EAA rig if you already own a telescope, or want a larger aperture or longer focal length than any smart telescope offers.

How the numbers are worked out

Field of view is twice the arctangent of half the sensor width (pixel size times pixel count) divided by the focal length; pixel scale is 206.265 times the pixel size in micrometers divided by the focal length in millimeters. An object fits if its long and short axes are under 90% of the frame's; it fills if its long axis is at least a quarter of the frame's short side. Object sizes come from this site's Messier and Caldwell datasets. Mosaic panels use the same 90% margin. Exposure ratios assume a sky-limited image, where sky glow sets the noise.