How long to image the M55 with the DwarfLab DWARF II
From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 46 min (184 subs of 15 s) for a solid image of the M55. A quick look takes 11 min; a showpiece 3 h 04 min. Under a Bortle 3 rural sky the solid figure drops to 26 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 18% 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 | 6 min24 subs | 24 min95 subs | 1 h 34 min378 subs |
| Bortle 2Typical dark site | 6 min25 subs | 24 min98 subs | 1 h 37 min389 subs |
| Bortle 3Rural | 6 min26 subs | 26 min103 subs | 1 h 42 min410 subs |
| Bortle 4Rural / suburban transition | 7 min29 subs | 29 min115 subs | 1 h 55 min460 subs |
| Bortle 5Suburban | 8 min34 subs | 34 min135 subs | 2 h 15 min540 subs |
| Bortle 6Bright suburban | 11 min46 subs | 46 min184 subs | 3 h 04 min735 subs |
| Bortle 7Suburban / urban transition | 17 min70 subs | 1 h 09 min277 subs | 4 h 37 min1,107 subs |
| Bortle 8City | 26 min106 subs | 1 h 45 min422 subs | 7 h 01 min1,685 subs |
| Bortle 9Inner city | 46 min183 subs | 3 h 02 min730 subs | 12 h2,918 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h of run time. The DWARF II’s battery (rated about 3 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 PD power bank 10000mAh 18W18 W PD input; runs while charging.
- 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 II →
How it frames
The M55 is 19′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 18% of the frame’s short side.
About the M55
A large, loose globular that resolves easily but sits low for northern imagers.
NGC 6809 · Globular cluster in Sagittarius · magnitude 6.3 · 19′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.
About the DwarfLab DWARF II
The original pocket scope. 24 mm aperture and tiny 1.45 µm pixels mean it is slow per pixel, so bin or downsample and be patient.
15 s is the hard maximum in any mode; DwarfLab recommends EQ mode at 15 s. Two built-in filters, VIS and Astro (IR-pass); no dual-band. The optional UHC filter is no longer sold.
The DWARF II uses fixed 15 s subs, so the only levers you have are the sky you shoot from, the filter, and total time.
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 M55 from a DWARF II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M55 with the ZWO Seestar S50: 14 min from Bortle 6
- M55 with the ZWO Seestar S50 Pro: 15 min from Bortle 6
- M55 with the ZWO Seestar S30: 14 min from Bortle 6
- M55 with the ZWO Seestar S30 Pro: 16 min from Bortle 6
- M55 with the DwarfLab DWARF 3: 20 min from Bortle 6
- M55 with the DwarfLab DWARF mini: 14 min from Bortle 6
- M55 with the DwarfLab Draco: 15 min from Bortle 6
- M55 with the Vaonis Vespera II: 14 min from Bortle 6
- M55 with the Vaonis Vespera Pro: 31 min from Bortle 6
- M55 with the Vaonis Vespera 3: 13 min from Bortle 6
- M55 with the Vaonis Vespera Pro 2: 29 min from Bortle 6
- M55 with the Unistellar eQuinox 2: 12 min from Bortle 6
- M55 with the Unistellar Odyssey: 54 min from Bortle 6
- M55 with the Celestron Origin: 5 min from Bortle 6
- M55 with the Celestron Origin Mark II: 5 min from Bortle 6