How long to image the M4 with the DwarfLab DWARF II
From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 4 h 14 min (1,016 subs of 15 s) for a solid image of the M4. A quick look takes 1 h 03 min; a showpiece 17 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 08 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 33% 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 | 29 min117 subs | 1 h 56 min466 subs | 7 h 45 min1,861 subs |
| Bortle 2Typical dark site | 30 min121 subs | 2 h482 subs | 8 h 02 min1,928 subs |
| Bortle 3Rural | 32 min129 subs | 2 h 08 min514 subs | 8 h 34 min2,056 subs |
| Bortle 4Rural / suburban transition | 37 min148 subs | 2 h 28 min592 subs | 9 h 51 min2,366 subs |
| Bortle 5Suburban | 45 min179 subs | 2 h 59 min715 subs | 12 h2,857 subs |
| Bortle 6Bright suburban | 1 h 03 min254 subs | 4 h 14 min1,016 subs | 17 h4,063 subs |
| Bortle 7Suburban / urban transition | 1 h 39 min398 subs | 6 h 37 min1,590 subs | 26 h6,359 subs |
| Bortle 8City | 2 h 35 min621 subs | 10 h2,482 subs | 41 h9,925 subs |
| Bortle 9Inner city | 4 h 34 min1,096 subs | 18 h4,383 subs | 73 h17,529 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 5 h 30 min of run time. The DWARF II’s battery is rated at about 3 h, so the session needs an external power bank. (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 M4 is 36′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 33% of the frame’s short side.
About the M4
The loose globular next to Antares. Low in the sky from the UK, so image it near transit.
NGC 6121 · Globular cluster in Scorpius · magnitude 5.9 · 36′ · best in May, Jun, Jul. 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 M4 from a DWARF II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M4 with the ZWO Seestar S50: 1 h 14 min from Bortle 6
- M4 with the ZWO Seestar S50 Pro: 1 h 21 min from Bortle 6
- M4 with the ZWO Seestar S30: 1 h 18 min from Bortle 6
- M4 with the ZWO Seestar S30 Pro: 1 h 26 min from Bortle 6
- M4 with the DwarfLab DWARF 3: 1 h 48 min from Bortle 6
- M4 with the DwarfLab DWARF mini: 1 h 14 min from Bortle 6
- M4 with the DwarfLab Draco: 1 h 01 min from Bortle 6
- M4 with the Vaonis Vespera II: 1 h 14 min from Bortle 6
- M4 with the Vaonis Vespera Pro: 2 h 46 min from Bortle 6
- M4 with the Vaonis Vespera 3: 1 h 11 min from Bortle 6
- M4 with the Vaonis Vespera Pro 2: 2 h 39 min from Bortle 6
- M4 with the Unistellar eQuinox 2: 1 h 07 min from Bortle 6
- M4 with the Unistellar Odyssey: 5 h 11 min from Bortle 6
- M4 with the Celestron Origin: 20 min from Bortle 6
- M4 with the Celestron Origin Mark II: 27 min from Bortle 6