How long to image the Cocoon Nebula with the DwarfLab DWARF 3
From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 3 h 39 min (875 subs of 15 s with the built-in dual-band filter) for a solid image of the Cocoon Nebula. A quick look takes 55 min; a showpiece 15 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 12 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 12% 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 | 31 min124 subs | 2 h 03 min494 subs | 8 h 14 min1,975 subs |
| Bortle 2Typical dark site | 32 min127 subs | 2 h 06 min506 subs | 8 h 25 min2,022 subs |
| Bortle 3Rural | 33 min132 subs | 2 h 12 min528 subs | 8 h 47 min2,110 subs |
| Bortle 4Rural / suburban transition | 36 min146 subs | 2 h 25 min581 subs | 9 h 41 min2,324 subs |
| Bortle 5Suburban | 42 min167 subs | 2 h 46 min666 subs | 11 h2,664 subs |
| Bortle 6Bright suburban | 55 min219 subs | 3 h 39 min875 subs | 15 h3,498 subs |
| Bortle 7Suburban / urban transition | 1 h 19 min318 subs | 5 h 18 min1,272 subs | 21 h5,087 subs |
| Bortle 8City | 1 h 58 min473 subs | 7 h 52 min1,889 subs | 31 h7,553 subs |
| Bortle 9Inner city | 3 h 20 min801 subs | 13 h3,204 subs | 53 h12,814 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 4 h 44 min of run time. The DWARF 3’s battery is rated at about 5 h 30 min, which is cutting it fine; take a power bank. (Bortle 6, solid image; we allow 30% over the integration time.)
- USB-C PD power bank 20000mAh 18W18 W PD input and it runs while charging; needs a C-to-C cable for PD.
- 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 3 →
How it frames
The Cocoon Nebula is 12′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it fills 12% of the frame’s short side.
Longer subs
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 15 s | 2 h 12 min528 subs | 2 h 46 min666 subs | 5 h 18 min1,272 subs |
| 30 s | 1 h 52 min224 subs | 2 h 26 min293 subs | 4 h 58 min596 subs |
| 60 s | 1 h 42 min102 subs | 2 h 16 min137 subs | 4 h 48 min288 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| Astro (no light-pollution filter) | 2 h 16 min543 subs | 4 h 09 min996 subs | 12 h2,974 subs |
| dual-band | 2 h 12 min528 subs | 2 h 46 min666 subs | 5 h 18 min1,272 subs |
About the Cocoon Nebula
A round emission and reflection nebula at the end of a long dark lane. Mixed light, so a broadband stack keeps the blue.
IC 5146, Caldwell 19 · Emission nebula in Cygnus · magnitude 7.2 · 12′ · best in Jul, Aug, Sep. 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 DWARF 3
Small pixels on a 35 mm f/4.3 lens give a sharper image than its aperture suggests, and EQ mode with 60 s subs makes it the read-noise winner in dark skies.
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Three built-in filters: VIS, Astro (430 to 690 nm) and dual-band Hα 656 nm / OIII 501 nm.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 15 s and 60 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 Cocoon Nebula from a DWARF 3? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Cocoon Nebula with the ZWO Seestar S50: 2 h 58 min from Bortle 6
- Cocoon Nebula with the ZWO Seestar S50 Pro: 3 h 20 min from Bortle 6
- Cocoon Nebula with the ZWO Seestar S30: 3 h 29 min from Bortle 6
- Cocoon Nebula with the ZWO Seestar S30 Pro: 3 h 36 min from Bortle 6
- Cocoon Nebula with the DwarfLab DWARF mini: 2 h 55 min from Bortle 6
- Cocoon Nebula with the DwarfLab Draco: 2 h 21 min from Bortle 6
- Cocoon Nebula with the DwarfLab DWARF II: 17 h from Bortle 6
- Cocoon Nebula with the Vaonis Vespera II: 4 h 49 min from Bortle 6
- Cocoon Nebula with the Vaonis Vespera Pro: 11 h from Bortle 6
- Cocoon Nebula with the Vaonis Vespera 3: 4 h 36 min from Bortle 6
- Cocoon Nebula with the Vaonis Vespera Pro 2: 10 h from Bortle 6
- Cocoon Nebula with the Unistellar eQuinox 2: 4 h 25 min from Bortle 6
- Cocoon Nebula with the Unistellar Odyssey: 21 h from Bortle 6
- Cocoon Nebula with the Celestron Origin: 1 h 16 min from Bortle 6
- Cocoon Nebula with the Celestron Origin Mark II: 1 h 44 min from Bortle 6
All telescopes for the Cocoon Nebula · All targets for the DWARF 3