How long to image the California Nebula with the DwarfLab Draco
From a Bortle 6 suburban sky, the DwarfLab Draco needs about 1 h 35 min (190 subs of 30 s with the built-in dual-narrowband (Hα + OIII) filter) for a solid image of the California Nebula. A quick look takes 24 min; a showpiece 6 h 19 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 04 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is 2.1× wider than the frame.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 15 min31 subs | 1 h 01 min122 subs | 4 h 02 min485 subs |
| Bortle 2Typical dark site | 15 min31 subs | 1 h 02 min124 subs | 4 h 06 min493 subs |
| Bortle 3Rural | 16 min32 subs | 1 h 04 min128 subs | 4 h 14 min509 subs |
| Bortle 4Rural / suburban transition | 17 min35 subs | 1 h 08 min137 subs | 4 h 34 min548 subs |
| Bortle 5Suburban | 19 min39 subs | 1 h 16 min153 subs | 5 h 04 min609 subs |
| Bortle 6Bright suburban | 24 min48 subs | 1 h 35 min190 subs | 6 h 19 min759 subs |
| Bortle 7Suburban / urban transition | 33 min66 subs | 2 h 10 min261 subs | 8 h 42 min1,044 subs |
| Bortle 8City | 46 min93 subs | 3 h 06 min372 subs | 12 h1,487 subs |
| Bortle 9Inner city | 1 h 16 min152 subs | 5 h 04 min608 subs | 20 h2,431 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 03 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 December 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 California Nebula is 160′ × 40′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it is 2.1× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.
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 | 1 h 04 min128 subs | 1 h 16 min153 subs | 2 h 10 min261 subs |
| 60 s | 46 min47 subs | 59 min59 subs | 1 h 53 min113 subs |
| 120 s | 1 h30 subs | 1 h30 subs | 1 h 44 min53 subs |
| 300 s | 2 h 30 min30 subs | 2 h 30 min30 subs | 2 h 30 min30 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| No filter | 57 min114 subs | 1 h 38 min196 subs | 4 h 35 min551 subs |
| dual-narrowband (Hα + OIII) | 1 h 04 min128 subs | 1 h 16 min153 subs | 2 h 10 min261 subs |
About the California Nebula
A long, faint hydrogen streak near Menkib, nearly three degrees end to end. Needs a wide field and a dual-band filter; it is almost invisible in broadband.
NGC 1499 · Emission nebula in Perseus · magnitude 6.0 · 160′ × 40′ · best in Nov, Dec, Jan. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.
Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.
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 California Nebula from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- California Nebula with the ZWO Seestar S50: 2 h from Bortle 6
- California Nebula with the ZWO Seestar S50 Pro: 2 h 15 min from Bortle 6
- California Nebula with the ZWO Seestar S30: 2 h 20 min from Bortle 6
- California Nebula with the ZWO Seestar S30 Pro: 2 h 25 min from Bortle 6
- California Nebula with the DwarfLab DWARF 3: 2 h 28 min from Bortle 6
- California Nebula with the DwarfLab DWARF mini: 1 h 58 min from Bortle 6
- California Nebula with the DwarfLab DWARF II: 11 h from Bortle 6
- California Nebula with the Vaonis Vespera II: 3 h 13 min from Bortle 6
- California Nebula with the Vaonis Vespera Pro: 7 h 14 min from Bortle 6
- California Nebula with the Vaonis Vespera 3: 3 h 05 min from Bortle 6
- California Nebula with the Vaonis Vespera Pro 2: 6 h 53 min from Bortle 6
- California Nebula with the Unistellar eQuinox 2: 2 h 57 min from Bortle 6
- California Nebula with the Unistellar Odyssey: 14 h from Bortle 6
- California Nebula with the Celestron Origin: 51 min from Bortle 6
- California Nebula with the Celestron Origin Mark II: 1 h 10 min from Bortle 6
All telescopes for the California Nebula · All targets for the Draco