How long to image the NGC 6781 with the DwarfLab Draco
From a Bortle 6 suburban sky, the DwarfLab Draco needs about 2 h 08 min (257 subs of 30 s with the built-in dual-narrowband (Hα + OIII) filter) for a solid image of the NGC 6781. A quick look takes 32 min; a showpiece 8 h 34 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 28 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 2% 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 | 21 min43 subs | 1 h 24 min169 subs | 5 h 37 min674 subs |
| Bortle 2Typical dark site | 21 min43 subs | 1 h 26 min172 subs | 5 h 42 min685 subs |
| Bortle 3Rural | 22 min45 subs | 1 h 28 min177 subs | 5 h 52 min705 subs |
| Bortle 4Rural / suburban transition | 24 min48 subs | 1 h 34 min189 subs | 6 h 17 min755 subs |
| Bortle 5Suburban | 26 min53 subs | 1 h 44 min209 subs | 6 h 57 min834 subs |
| Bortle 6Bright suburban | 32 min65 subs | 2 h 08 min257 subs | 8 h 34 min1,028 subs |
| Bortle 7Suburban / urban transition | 44 min88 subs | 2 h 55 min350 subs | 12 h1,397 subs |
| Bortle 8City | 1 h 02 min124 subs | 4 h 06 min493 subs | 16 h1,970 subs |
| Bortle 9Inner city | 1 h 40 min200 subs | 6 h 39 min799 subs | 27 h3,193 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 47 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.
Affiliate links: the retailer pays us a small commission and you pay the same price. These are search links to the named product, not endorsements of a particular listing; check the listing matches your model.
Everything that fits the Draco →
How it frames
The NGC 6781 is 1.8′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 2% 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 | 1 h 28 min177 subs | 1 h 44 min209 subs | 2 h 55 min350 subs |
| 60 s | 1 h 05 min66 subs | 1 h 22 min82 subs | 2 h 32 min152 subs |
| 120 s | 1 h30 subs | 1 h 10 min36 subs | 2 h 21 min71 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 | 1 h 18 min156 subs | 2 h 10 min261 subs | 6 h721 subs |
| dual-narrowband (Hα + OIII) | 1 h 28 min177 subs | 1 h 44 min209 subs | 2 h 55 min350 subs |
About the NGC 6781
A ghostly ring planetary in Aquila, larger and fainter than the Ring Nebula. Dual-band recommended.
Aquila planetary · Planetary nebula in Aquila · magnitude 11.4 · 1.8′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.
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 NGC 6781 from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- NGC 6781 with the ZWO Seestar S50: 2 h 42 min from Bortle 6
- NGC 6781 with the ZWO Seestar S50 Pro: 3 h 02 min from Bortle 6
- NGC 6781 with the ZWO Seestar S30: 3 h 09 min from Bortle 6
- NGC 6781 with the ZWO Seestar S30 Pro: 3 h 16 min from Bortle 6
- NGC 6781 with the DwarfLab DWARF 3: 3 h 22 min from Bortle 6
- NGC 6781 with the DwarfLab DWARF mini: 2 h 40 min from Bortle 6
- NGC 6781 with the DwarfLab DWARF II: 15 h from Bortle 6
- NGC 6781 with the Vaonis Vespera II: 4 h 15 min from Bortle 6
- NGC 6781 with the Vaonis Vespera Pro: 9 h 32 min from Bortle 6
- NGC 6781 with the Vaonis Vespera 3: 4 h 04 min from Bortle 6
- NGC 6781 with the Vaonis Vespera Pro 2: 9 h 05 min from Bortle 6
- NGC 6781 with the Unistellar eQuinox 2: 3 h 52 min from Bortle 6
- NGC 6781 with the Unistellar Odyssey: 18 h from Bortle 6
- NGC 6781 with the Celestron Origin: 1 h 07 min from Bortle 6
- NGC 6781 with the Celestron Origin Mark II: 1 h 33 min from Bortle 6