How long to image the Pleiades with the ZWO Seestar S30
From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 2 h 50 min (1,022 subs of 10 s) for a solid image of the Pleiades. A quick look takes 43 min; a showpiece 11 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 09 min. At Bortle 6 the limit is skyglow, so a darker site or a filter helps more than longer subs. In this scope's field it is 1.5× wider than the frame.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 15 min89 subs | 59 min353 subs | 3 h 55 min1,410 subs |
| Bortle 2Typical dark site | 16 min94 subs | 1 h 02 min374 subs | 4 h 09 min1,493 subs |
| Bortle 3Rural | 17 min103 subs | 1 h 09 min412 subs | 4 h 35 min1,648 subs |
| Bortle 4Rural / suburban transition | 21 min127 subs | 1 h 24 min506 subs | 5 h 37 min2,024 subs |
| Bortle 5Suburban | 27 min164 subs | 1 h 49 min656 subs | 7 h 17 min2,621 subs |
| Bortle 6Bright suburban | 43 min256 subs | 2 h 50 min1,022 subs | 11 h4,085 subs |
| Bortle 7Suburban / urban transition | 1 h 12 min430 subs | 4 h 46 min1,719 subs | 19 h6,874 subs |
| Bortle 8City | 1 h 57 min701 subs | 7 h 47 min2,801 subs | 31 h11,204 subs |
| Bortle 9Inner city | 3 h 33 min1,278 subs | 14 h5,110 subs | 57 h20,440 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 41 min of run time. The Seestar S30’s battery is rated at about 6 h, less near freezing, which is cutting it fine; take a power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a November night.)
- USB-C power bank 10000mAh 5V 3A6,000 mAh inside; a 10,000 mAh 5 V 3 A bank roughly doubles a session.
- Seestar S30 dew shieldHeater is built in; a cheap shield reduces dew and stray light.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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Everything that fits the Seestar S30 →
How it frames
The Pleiades is 110′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it is 1.5× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 1 h 09 min412 subs | 1 h 49 min656 subs | 4 h 46 min1,719 subs |
| 20 s | 55 min165 subs | 1 h 36 min287 subs | 4 h 33 min819 subs |
| 30 s | 50 min101 subs | 1 h 31 min182 subs | 4 h 28 min537 subs |
| 60 s | 46 min46 subs | 1 h 26 min87 subs | 4 h 24 min264 subs |
Leave the dual-band filter out for the Pleiades. It is a reflection nebula, and it shines right across the spectrum. A dual-band filter keeps two emission lines and throws the rest away, so most of the light you came for is being stopped along with the sky. From a Bortle 6 sky it would be roughly 14 times slower.
About the Pleiades
The stars take seconds. The blue reflection nebulosity around them is faint and needs hours from any sky, and no filter helps because it is starlight, not emission.
M45, Seven Sisters · Reflection nebula in Taurus · magnitude 1.6 · 110′ · best in Oct, Nov, Dec. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Reflection nebulae are starlight scattered by dust, so they are broadband and blue. A dual-band filter removes almost all of it; do not use one. These are among the faintest structures a smart scope can attempt and the figures run long. A dark sky matters more here than for any other type, and the Moon must be down.
About the ZWO Seestar S30
Wider and lighter than the S50 with the same 2.9 µm pixels, so its per-pixel speed on extended targets is close despite the smaller aperture. Ideal for big nebulae.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 60 s subs is small; from a rural site it can halve the total time, especially with a dual-band filter in place.
Stack across nights. Every smart scope app can continue a stack or you can combine the saved frames on a computer; the figures here are totals, not single-session limits.
Have an image of the Pleiades from a Seestar S30? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Pleiades with the ZWO Seestar S50: 2 h 42 min from Bortle 6
- Pleiades with the ZWO Seestar S50 Pro: 2 h 57 min from Bortle 6
- Pleiades with the ZWO Seestar S30 Pro: 3 h 08 min from Bortle 6
- Pleiades with the DwarfLab DWARF 3: 3 h 55 min from Bortle 6
- Pleiades with the DwarfLab DWARF mini: 2 h 41 min from Bortle 6
- Pleiades with the DwarfLab Draco: 2 h 13 min from Bortle 6
- Pleiades with the DwarfLab DWARF II: 9 h 16 min from Bortle 6
- Pleiades with the Vaonis Vespera II: 2 h 42 min from Bortle 6
- Pleiades with the Vaonis Vespera Pro: 6 h 03 min from Bortle 6
- Pleiades with the Vaonis Vespera 3: 2 h 35 min from Bortle 6
- Pleiades with the Vaonis Vespera Pro 2: 5 h 46 min from Bortle 6
- Pleiades with the Unistellar eQuinox 2: 2 h 28 min from Bortle 6
- Pleiades with the Unistellar Odyssey: 11 h from Bortle 6
- Pleiades with the Celestron Origin: 43 min from Bortle 6
- Pleiades with the Celestron Origin Mark II: 59 min from Bortle 6
All telescopes for the Pleiades · All targets for the Seestar S30