How long to image the Little Dumbbell with the DwarfLab DWARF mini
From a Bortle 6 suburban sky, the DwarfLab DWARF mini needs about 32 min (129 subs of 15 s with the built-in dual-band filter) for a solid image of the Little Dumbbell. A quick look takes 8 min; a showpiece 2 h 09 min. Under a Bortle 3 rural sky the solid figure drops to 24 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 41 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 6 min24 subs | 24 min95 subs | 1 h 35 min380 subs |
| Bortle 2Typical dark site | 6 min24 subs | 24 min96 subs | 1 h 36 min384 subs |
| Bortle 3Rural | 6 min25 subs | 24 min98 subs | 1 h 38 min392 subs |
| Bortle 4Rural / suburban transition | 6 min26 subs | 26 min103 subs | 1 h 43 min411 subs |
| Bortle 5Suburban | 7 min28 subs | 28 min111 subs | 1 h 50 min441 subs |
| Bortle 6Bright suburban | 8 min33 subs | 32 min129 subs | 2 h 09 min515 subs |
| Bortle 7Suburban / urban transition | 10 min41 subs | 41 min164 subs | 2 h 44 min655 subs |
| Bortle 8City | 14 min55 subs | 55 min219 subs | 3 h 38 min873 subs |
| Bortle 9Inner city | 21 min84 subs | 1 h 24 min335 subs | 5 h 34 min1,338 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 42 min of run time. The DWARF mini’s battery (rated about 3 h 30 min) 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 PD power bank 10000mAh 20W7,000 mAh inside, about four hours; a PD bank extends the night.
- 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 DWARF mini →
How it frames
The Little Dumbbell is 2.7′ × 1.8′ across. The DWARF mini frames 2.13° × 1.20° at 3.99″ per pixel, so it is small in the frame, about 41 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
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 15 s | 24 min98 subs | 28 min111 subs | 41 min164 subs |
| 30 s | 20 min40 subs | 23 min46 subs | 36 min73 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 34 min35 subs |
| 90 s | 45 min30 subs | 45 min30 subs | 45 min30 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| Astro (no light-pollution filter) | 20 min81 subs | 30 min121 subs | 1 h 14 min295 subs |
| dual-band | 24 min98 subs | 28 min111 subs | 41 min164 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 DwarfLab DWARF mini
DwarfLab’s answer to the Seestar S30: same sensor and focal length, big pixels, dual-band filter built in, and 90 s subs in EQ mode. Sensitivity over megapixels.
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Built-in Astro (430 to 690 nm), dark-frame and dual-band Hα / OIII filters; no plain VIS filter on the tele camera.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 15 s and 90 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 DWARF mini? 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 ZWO Seestar S30 Pro: 39 min from Bortle 6
- Little Dumbbell with the DwarfLab DWARF 3: 43 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 DWARF mini