How long to image the Pleiades with the DwarfLab Draco
From a Bortle 6 suburban sky, the DwarfLab Draco needs about 2 h 13 min (266 subs of 30 s) for a solid image of the Pleiades. A quick look takes 33 min; a showpiece 8 h 51 min. Under a Bortle 3 rural sky the solid figure drops to 48 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 is just over the frame at 1.5×.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 10 min20 subs | 40 min80 subs | 2 h 40 min320 subs |
| Bortle 2Typical dark site | 11 min22 subs | 43 min86 subs | 2 h 51 min342 subs |
| Bortle 3Rural | 12 min25 subs | 48 min97 subs | 3 h 13 min386 subs |
| Bortle 4Rural / suburban transition | 15 min31 subs | 1 h 01 min123 subs | 4 h 05 min490 subs |
| Bortle 5Suburban | 20 min41 subs | 1 h 22 min164 subs | 5 h 28 min656 subs |
| Bortle 6Bright suburban | 33 min67 subs | 2 h 13 min266 subs | 8 h 51 min1,063 subs |
| Bortle 7Suburban / urban transition | 57 min115 subs | 3 h 50 min460 subs | 15 h1,838 subs |
| Bortle 8City | 1 h 35 min191 subs | 6 h 20 min761 subs | 25 h3,041 subs |
| Bortle 9Inner city | 2 h 55 min351 subs | 12 h1,402 subs | 47 h5,607 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 53 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, and 30% off the battery for a November night.)
- 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.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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Everything that fits the Draco →
How it frames
The Pleiades is 110′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it is just over the frame at 1.5×. Point at the part you want; the edges will fall outside the frame.
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 | 48 min97 subs | 1 h 22 min164 subs | 3 h 50 min460 subs |
| 60 s | 41 min42 subs | 1 h 15 min75 subs | 3 h 43 min223 subs |
| 120 s | 1 h30 subs | 1 h 11 min36 subs | 3 h 39 min110 subs |
| 300 s | 2 h 30 min30 subs | 2 h 30 min30 subs | 3 h 37 min44 subs |
Leave the dual-band filter out for the Pleiades. It is a reflection nebula, 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 11 times slower.
About the Pleiades
The stars take seconds. The blue reflection nebulosity around them is faint and needs hours from any sky, and no filter helps because it is starlight, not emission.
M45, Seven Sisters · Reflection nebula in Taurus · magnitude 1.6 · 110′ · best in Oct, Nov, Dec. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Reflection nebulae are starlight scattered by dust, so they are broadband and blue. A dual-band filter removes almost all of it; do not use one. These are among the faintest structures a smart scope can attempt and the figures run long. A dark sky matters more here than for any other type, and the Moon must be down.
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 Pleiades from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Pleiades with the ZWO Seestar S50: 2 h 42 min from Bortle 6
- Pleiades with the ZWO Seestar S50 Pro: 2 h 57 min from Bortle 6
- Pleiades with the ZWO Seestar S30: 2 h 50 min from Bortle 6
- Pleiades with the ZWO Seestar S30 Pro: 3 h 08 min from Bortle 6
- Pleiades with the DwarfLab DWARF 3: 3 h 55 min from Bortle 6
- Pleiades with the DwarfLab DWARF mini: 2 h 41 min from Bortle 6
- Pleiades with the DwarfLab DWARF II: 9 h 16 min from Bortle 6
- Pleiades with the Vaonis Vespera II: 2 h 42 min from Bortle 6
- Pleiades with the Vaonis Vespera Pro: 6 h 03 min from Bortle 6
- Pleiades with the Vaonis Vespera 3: 2 h 35 min from Bortle 6
- Pleiades with the Vaonis Vespera Pro 2: 5 h 46 min from Bortle 6
- Pleiades with the Unistellar eQuinox 2: 2 h 28 min from Bortle 6
- Pleiades with the Unistellar Odyssey: 11 h from Bortle 6
- Pleiades with the Celestron Origin: 43 min from Bortle 6
- Pleiades with the Celestron Origin Mark II: 59 min from Bortle 6