How long to image the Pleiades with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 3 h 08 min (1,127 subs of 10 s) for a solid image of the Pleiades. A quick look takes 47 min; a showpiece 13 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 12 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 fills 82% of the frame’s short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 15 min92 subs | 1 h 01 min366 subs | 4 h 04 min1,462 subs |
| Bortle 2Typical dark site | 16 min98 subs | 1 h 05 min389 subs | 4 h 19 min1,556 subs |
| Bortle 3Rural | 18 min109 subs | 1 h 12 min433 subs | 4 h 49 min1,732 subs |
| Bortle 4Rural / suburban transition | 23 min136 subs | 1 h 30 min541 subs | 6 h2,161 subs |
| Bortle 5Suburban | 30 min178 subs | 1 h 58 min710 subs | 7 h 53 min2,839 subs |
| Bortle 6Bright suburban | 47 min282 subs | 3 h 08 min1,127 subs | 13 h4,505 subs |
| Bortle 7Suburban / urban transition | 1 h 20 min480 subs | 5 h 20 min1,920 subs | 21 h7,678 subs |
| Bortle 8City | 2 h 11 min788 subs | 8 h 45 min3,152 subs | 35 h12,605 subs |
| Bortle 9Inner city | 4 h 01 min1,445 subs | 16 h5,779 subs | 64 h23,113 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 4 h 04 min of run time. The Seestar S30 Pro’s battery is rated at about 5 h, less near freezing, so the session needs an external 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 3A5 V 3 A input and it runs while charging.
- Seestar S30 Pro dew shieldActive anti-dew is built in; a shield adds margin. The S30 Pro front differs from the S30, so check the listing.
- 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 Pro →
How it frames
The Pleiades is 110′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 82% of the frame’s short side.
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 12 min433 subs | 1 h 58 min710 subs | 5 h 20 min1,920 subs |
| 20 s | 1 h180 subs | 1 h 46 min318 subs | 5 h 08 min923 subs |
| 30 s | 56 min112 subs | 1 h 42 min204 subs | 5 h 04 min608 subs |
| 60 s | 52 min52 subs | 1 h 38 min98 subs | 4 h 59 min300 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 13 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 Pro
The S30 optics upgraded to a quadruplet in front of an 8 MP IMX585. Same speed per pixel as the S30, four times the pixels, so you can crop hard.
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 on the telephoto camera.
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 Pro? 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: 2 h 50 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 Pro