How to read the results
Each target gets a color-coded verdict. Shows up in minutes means the object appears on your phone almost as soon as stacking starts: the Moon, bright clusters, the Orion Nebula, the Dumbbell. Good in one session means under an hour for a pleasing result. Long session is one to three hours,multi-night project is three to ten hours spread over several nights (Vespera 3 and Pro 2 can resume a stack automatically), and not realistic means more than ten hours from that sky with that scope.
The thumbnail shows the scope's field (blue box) with the target drawn to scale. Big targets such as the Andromeda Galaxy, the North America Nebula or the Heart Nebula overflow small fields and need a mosaic; tiny ones such as the Ring Nebula or planets fill only a few dozen pixels. The framing calculator draws one target in every scope's frame side by side.
| Class | Sky | mag/arcsec² | What a 30–50 mm smart scope can do |
|---|---|---|---|
| Bortle 1 | Excellent dark sky Remote desert or mountain site; zodiacal light and airglow visible | ~22.0 | Everything on the list is possible; faint galaxies and big H-alpha regions shine. |
| Bortle 2 | Typical truly dark site Remote rural area; Milky Way shows structure | ~21.9 | Faint nebulae and galaxy halos in a session or two. |
| Bortle 3 | Rural sky Some glow on the horizon; Milky Way still complex | ~21.7 | Excellent for nearly every target; the Milky Way casts structure. |
| Bortle 4 | Rural/suburban transition Light domes over towns; Milky Way visible but washed out near the horizon | ~21.1 | Most showpieces in under an hour; faint galaxies need longer. |
| Bortle 5 | Suburban sky Milky Way faint or invisible near the horizon | ~20.0 | Nebulae need a dual-band filter for best results; galaxies take hours. |
| Bortle 6 | Bright suburban sky Milky Way only near the zenith, if at all | ~19.2 | Bright targets fine; faint galaxies become multi-night projects. |
| Bortle 7 | Suburban/urban transition Gray-orange sky; Milky Way invisible | ~18.7 | Moon, planets, clusters and bright nebulae with a filter; galaxies are hard. |
| Bortle 8 | City sky Only bright constellations visible | ~18.2 | Stick to the Moon, Sun, planets, clusters and the brightest nebulae with a dual-band filter. |
| Bortle 9 | Inner-city sky Only the Moon, planets and a few bright stars | ~17.8 | Moon, Sun and planets; a handful of bright nebulae with narrowband filtering. |
Expectations are our editorial summary. Check your own sky with the sky target checker.
Realistic expectations vs marketing
Every result carries a "marketing vs reality" line, because the images on listings and boxes are rarely what a first night looks like. Nebula and galaxy photos in ads are typically hours of integration under dark skies; planet close-ups are often cropped or upscaled; prominence images come from hydrogen-alpha solar telescopes rather than the white-light filters smart scopes use. None of that makes smart telescopes a bad buy. They simply reward patience and dark skies like every other telescope. Our are smart telescopes worth it guide goes deeper.
How the estimate works
Each target has an editorial difficulty tier, from 1 (showpiece) to 5 (very faint), based on its catalog magnitude, size and average surface brightness, and on the results reviewers and owners typically publish. Magnitudes and sizes are rounded catalog values from the SEDS Messier data table and SEDS NGC/IC pages; surface brightness is computed from magnitude and area. The baseline times assume a Bortle 4 sky and f/5 optics with 2.9 µm pixels.
From there, sky brightness scales the time: in the background-limited regime, the time needed for the same signal-to-noise grows with the sky's brightness, so going from Bortle 4 (about 21.1 mag/arcsec²) to Bortle 8 (about 18.2) multiplies it many times over for faint targets. Bright targets are less sky-limited, so we soften that penalty for them. A dual-band filter removes most of the skyglow for emission nebulae; faster optics (lower f-number) and bigger pixels cut the time. A small aperture penalty applies to small, faint objects.
A worked example
Take a Seestar S50 Pro in a Bortle 6 suburb, with its built-in dual-band filter on. The Moon, the Pleiades, M13 and the Orion Nebula show up in minutes. The Lagoon Nebula comes out in a single session and the Rosette in a long evening. Andromeda's core is quick, but the full galaxy (about 3° long) is wider than the S50 Pro's 2.45° field, so it needs a two-panel mosaic. The Pinwheel Galaxy (M101), large and faint, becomes a multi-night project. Switch the sky to Bortle 3 and the galaxies move up a level or two; switch the scope to a Seestar S30 Pro and the big nebulae fit in one frame, but small galaxies shrink. That's the whole trade-off of smart telescopes in one screen.