How long to image the M3 with the DwarfLab Draco
From a Bortle 6 suburban sky, the DwarfLab Draco needs about 15 min (30 subs of 30 s) for a solid image of the M3. A quick look takes 5 min; a showpiece 45 min. Under a Bortle 3 rural sky the solid figure drops to 15 min. At Bortle 6 the limit is skyglow, so a darker site or a filter helps more than longer subs. In this scope's field it fills 24% 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 | 5 min10 subs | 15 min30 subs | 45 min90 subs |
| Bortle 2Typical dark site | 5 min10 subs | 15 min30 subs | 45 min90 subs |
| Bortle 3Rural | 5 min10 subs | 15 min30 subs | 45 min90 subs |
| Bortle 4Rural / suburban transition | 5 min10 subs | 15 min30 subs | 45 min90 subs |
| Bortle 5Suburban | 5 min10 subs | 15 min30 subs | 45 min90 subs |
| Bortle 6Bright suburban | 5 min10 subs | 15 min30 subs | 45 min90 subs |
| Bortle 7Suburban / urban transition | 5 min10 subs | 15 min30 subs | 50 min101 subs |
| Bortle 8City | 5 min10 subs | 20 min40 subs | 1 h 20 min160 subs |
| Bortle 9Inner city | 9 min18 subs | 35 min71 subs | 2 h 21 min283 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 20 min of run time. The Draco’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 PD power bank 20000mAhRated 5 h on its 10,000 mAh battery. DwarfLab has not published the charging input, so check PD support before relying on it mid-session.
- 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 Draco →
How it frames
The M3 is 18′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 24% of the frame’s short side.
Longer subs
Auto Mode picks the exposure; Pro Mode allows up to 300 s, held by built-in guiding and field derotation. The 30 s default here is our assumption. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 30 s | 15 min30 subs | 15 min30 subs | 15 min30 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 30 min30 subs |
| 120 s | 1 h30 subs | 1 h30 subs | 1 h30 subs |
| 300 s | 2 h 30 min30 subs | 2 h 30 min30 subs | 2 h 30 min30 subs |
Leave the dual-band filter out for the M3. It is a globular cluster, and it shines right across the spectrum. A dual-band filter keeps two emission lines and throws the rest away, so most of the light you came for is being stopped along with the sky. From a Bortle 6 sky it would be roughly 6 times slower.
About the M3
One of the finest northern globulars, half a million stars in a tight ball. A spring showpiece that needs little time.
NGC 5272 · Globular cluster in Canes Venatici · magnitude 6.2 · 18′ · best in Mar, Apr, May. 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 Draco
DwarfLab’s big scope: 90 mm of folded f/3.8 optics, the most aperture of any Seestar or DWARF, a narrow 13 nm dual-band filter and 300 s subs with built-in guiding. A small-target scope; big nebulae need its mosaic mode.
Auto Mode picks the exposure; Pro Mode allows up to 300 s, held by built-in guiding and field derotation. The 30 s default here is our assumption. Built-in Hα + OIII dual-narrowband filter, 13 nm per line; the SHO Edition adds an SII option.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 30 s and 300 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 M3 from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M3 with the ZWO Seestar S50: 10 min from Bortle 6
- M3 with the ZWO Seestar S50 Pro: 11 min from Bortle 6
- M3 with the ZWO Seestar S30: 10 min from Bortle 6
- M3 with the ZWO Seestar S30 Pro: 11 min from Bortle 6
- M3 with the DwarfLab DWARF 3: 14 min from Bortle 6
- M3 with the DwarfLab DWARF mini: 10 min from Bortle 6
- M3 with the DwarfLab DWARF II: 32 min from Bortle 6
- M3 with the Vaonis Vespera II: 10 min from Bortle 6
- M3 with the Vaonis Vespera Pro: 21 min from Bortle 6
- M3 with the Vaonis Vespera 3: 9 min from Bortle 6
- M3 with the Vaonis Vespera Pro 2: 20 min from Bortle 6
- M3 with the Unistellar eQuinox 2: 8 min from Bortle 6
- M3 with the Unistellar Odyssey: 37 min from Bortle 6
- M3 with the Celestron Origin: 5 min from Bortle 6
- M3 with the Celestron Origin Mark II: 5 min from Bortle 6