How long to image the Little Dumbbell with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 39 min (233 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Little Dumbbell. A quick look takes 10 min; a showpiece 2 h 35 min. Under a Bortle 3 rural sky the solid figure drops to 30 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is small in the frame, about 43 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 7 min44 subs | 29 min176 subs | 1 h 57 min702 subs |
| Bortle 2Typical dark site | 7 min45 subs | 30 min178 subs | 1 h 58 min709 subs |
| Bortle 3Rural | 8 min46 subs | 30 min181 subs | 2 h723 subs |
| Bortle 4Rural / suburban transition | 8 min48 subs | 31 min189 subs | 2 h 06 min755 subs |
| Bortle 5Suburban | 8 min51 subs | 34 min202 subs | 2 h 14 min806 subs |
| Bortle 6Bright suburban | 10 min59 subs | 39 min233 subs | 2 h 35 min932 subs |
| Bortle 7Suburban / urban transition | 12 min74 subs | 49 min293 subs | 3 h 15 min1,172 subs |
| Bortle 8City | 16 min97 subs | 1 h 04 min386 subs | 4 h 17 min1,544 subs |
| Bortle 9Inner city | 24 min147 subs | 1 h 37 min585 subs | 6 h 29 min2,337 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 50 min of run time. The Seestar S30 Pro’s battery (rated about 5 h) should cover it; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time.)
- 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.
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Everything that fits the Seestar S30 Pro →
How it frames
The Little Dumbbell is 2.7′ × 1.8′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it is small in the frame, about 43 pixels across. It is worth doing, but the result is a crop rather than a full frame; a longer focal length would resolve more of it.
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 | 30 min181 subs | 34 min202 subs | 49 min293 subs |
| 20 s | 24 min72 subs | 27 min83 subs | 43 min128 subs |
| 30 s | 22 min44 subs | 25 min51 subs | 41 min82 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 38 min39 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 24 min144 subs | 35 min212 subs | 1 h 25 min510 subs |
| dual-band (LP filter) | 30 min181 subs | 34 min202 subs | 49 min293 subs |
About the Little Dumbbell
A small, bright-per-pixel planetary in Perseus. Dual-band makes the two lobes and the faint wings much easier.
M76, NGC 650 · Planetary nebula in Perseus · magnitude 10.1 · 2.7′ × 1.8′ · best in Sep, Oct, Nov. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.
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 Little Dumbbell 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
- Little Dumbbell with the ZWO Seestar S50: 33 min from Bortle 6
- Little Dumbbell with the ZWO Seestar S50 Pro: 36 min from Bortle 6
- Little Dumbbell with the ZWO Seestar S30: 37 min from Bortle 6
- Little Dumbbell with the DwarfLab DWARF 3: 43 min from Bortle 6
- Little Dumbbell with the DwarfLab DWARF mini: 32 min from Bortle 6
- Little Dumbbell with the DwarfLab Draco: 26 min from Bortle 6
- Little Dumbbell with the DwarfLab DWARF II: 2 h 32 min from Bortle 6
- Little Dumbbell with the Vaonis Vespera II: 45 min from Bortle 6
- Little Dumbbell with the Vaonis Vespera Pro: 1 h 41 min from Bortle 6
- Little Dumbbell with the Vaonis Vespera 3: 43 min from Bortle 6
- Little Dumbbell with the Vaonis Vespera Pro 2: 1 h 36 min from Bortle 6
- Little Dumbbell with the Unistellar eQuinox 2: 40 min from Bortle 6
- Little Dumbbell with the Unistellar Odyssey: 3 h 01 min from Bortle 6
- Little Dumbbell with the Celestron Origin: 12 min from Bortle 6
- Little Dumbbell with the Celestron Origin Mark II: 17 min from Bortle 6
All telescopes for the Little Dumbbell · All targets for the Seestar S30 Pro