How long to image the M71 with the DwarfLab DWARF II
From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 1 h 03 min (252 subs of 15 s) for a solid image of the M71. A quick look takes 16 min; a showpiece 4 h 12 min. Under a Bortle 3 rural sky the solid figure drops to 36 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 7% 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 | 8 min34 subs | 34 min136 subs | 2 h 15 min541 subs |
| Bortle 2Typical dark site | 9 min35 subs | 35 min139 subs | 2 h 19 min555 subs |
| Bortle 3Rural | 9 min37 subs | 36 min146 subs | 2 h 25 min582 subs |
| Bortle 4Rural / suburban transition | 10 min41 subs | 40 min162 subs | 2 h 42 min648 subs |
| Bortle 5Suburban | 12 min47 subs | 47 min188 subs | 3 h 08 min752 subs |
| Bortle 6Bright suburban | 16 min63 subs | 1 h 03 min252 subs | 4 h 12 min1,007 subs |
| Bortle 7Suburban / urban transition | 23 min94 subs | 1 h 33 min374 subs | 6 h 13 min1,494 subs |
| Bortle 8City | 35 min141 subs | 2 h 21 min563 subs | 9 h 22 min2,250 subs |
| Bortle 9Inner city | 1 h242 subs | 4 h 01 min966 subs | 16 h3,861 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 22 min 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 M71 is 7′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 7% of the frame’s short side.
About the M71
A loose globular in Sagitta that was long mistaken for an open cluster. Rich Milky Way background.
NGC 6838 · Globular cluster in Sagitta · magnitude 8.2 · 7′ · 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 M71 from a DWARF II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M71 with the ZWO Seestar S50: 19 min from Bortle 6
- M71 with the ZWO Seestar S50 Pro: 21 min from Bortle 6
- M71 with the ZWO Seestar S30: 20 min from Bortle 6
- M71 with the ZWO Seestar S30 Pro: 22 min from Bortle 6
- M71 with the DwarfLab DWARF 3: 28 min from Bortle 6
- M71 with the DwarfLab DWARF mini: 19 min from Bortle 6
- M71 with the DwarfLab Draco: 16 min from Bortle 6
- M71 with the Vaonis Vespera II: 19 min from Bortle 6
- M71 with the Vaonis Vespera Pro: 42 min from Bortle 6
- M71 with the Vaonis Vespera 3: 18 min from Bortle 6
- M71 with the Vaonis Vespera Pro 2: 40 min from Bortle 6
- M71 with the Unistellar eQuinox 2: 16 min from Bortle 6
- M71 with the Unistellar Odyssey: 1 h 13 min from Bortle 6
- M71 with the Celestron Origin: 5 min from Bortle 6
- M71 with the Celestron Origin Mark II: 7 min from Bortle 6