How long to image the Iris Nebula with the DwarfLab DWARF mini
From a Bortle 6 suburban sky, the DwarfLab DWARF mini needs about 1 h 53 min (452 subs of 15 s) for a solid image of the Iris Nebula. A quick look takes 28 min; a showpiece 7 h 32 min. Under a Bortle 3 rural sky the solid figure drops to 43 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 25% 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 | 9 min36 subs | 36 min144 subs | 2 h 23 min574 subs |
| Bortle 2Typical dark site | 10 min39 subs | 38 min153 subs | 2 h 33 min612 subs |
| Bortle 3Rural | 11 min43 subs | 43 min171 subs | 2 h 51 min683 subs |
| Bortle 4Rural / suburban transition | 13 min54 subs | 54 min215 subs | 3 h 34 min857 subs |
| Bortle 5Suburban | 18 min71 subs | 1 h 11 min283 subs | 4 h 43 min1,132 subs |
| Bortle 6Bright suburban | 28 min113 subs | 1 h 53 min452 subs | 7 h 32 min1,807 subs |
| Bortle 7Suburban / urban transition | 48 min194 subs | 3 h 13 min774 subs | 13 h3,094 subs |
| Bortle 8City | 1 h 20 min319 subs | 5 h 18 min1,273 subs | 21 h5,091 subs |
| Bortle 9Inner city | 2 h 26 min585 subs | 9 h 44 min2,338 subs | 39 h9,351 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 27 min of run time. The DWARF mini’s battery (rated about 3 h 30 min) 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 10000mAh 20W7,000 mAh inside, about four hours; a PD bank extends the night.
- 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 mini →
How it frames
The Iris Nebula is 18′ across. The DWARF mini frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 25% of the frame’s short side.
Longer subs
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 15 s | 43 min171 subs | 1 h 11 min283 subs | 3 h 13 min774 subs |
| 30 s | 36 min73 subs | 1 h 04 min129 subs | 3 h 07 min375 subs |
| 60 s | 33 min34 subs | 1 h 01 min62 subs | 3 h 04 min184 subs |
| 90 s | 45 min30 subs | 1 h41 subs | 3 h 03 min122 subs |
Leave the dual-band filter out for the Iris Nebula. 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 12 times slower.
About the Iris Nebula
A blue reflection nebula wrapped in dark dust. No filter helps, and the surrounding dust needs a dark sky and hours.
NGC 7023, Caldwell 4 · Reflection nebula in Cepheus · magnitude 6.8 · 18′ · best in Jul, Aug, Sep. 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 DWARF mini
DwarfLab’s answer to the Seestar S30: same sensor and focal length, big pixels, dual-band filter built in, and 90 s subs in EQ mode. Sensitivity over megapixels.
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Built-in Astro (430 to 690 nm), dark-frame and dual-band Hα / OIII filters; no plain VIS filter on the tele camera.
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 90 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 Iris Nebula from a DWARF mini? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Iris Nebula with the ZWO Seestar S50: 1 h 53 min from Bortle 6
- Iris Nebula with the ZWO Seestar S50 Pro: 2 h 04 min from Bortle 6
- Iris Nebula with the ZWO Seestar S30: 1 h 59 min from Bortle 6
- Iris Nebula with the ZWO Seestar S30 Pro: 2 h 12 min from Bortle 6
- Iris Nebula with the DwarfLab DWARF 3: 2 h 45 min from Bortle 6
- Iris Nebula with the DwarfLab Draco: 1 h 33 min from Bortle 6
- Iris Nebula with the DwarfLab DWARF II: 6 h 29 min from Bortle 6
- Iris Nebula with the Vaonis Vespera II: 1 h 53 min from Bortle 6
- Iris Nebula with the Vaonis Vespera Pro: 4 h 14 min from Bortle 6
- Iris Nebula with the Vaonis Vespera 3: 1 h 48 min from Bortle 6
- Iris Nebula with the Vaonis Vespera Pro 2: 4 h 02 min from Bortle 6
- Iris Nebula with the Unistellar eQuinox 2: 1 h 43 min from Bortle 6
- Iris Nebula with the Unistellar Odyssey: 7 h 58 min from Bortle 6
- Iris Nebula with the Celestron Origin: 30 min from Bortle 6
- Iris Nebula with the Celestron Origin Mark II: 41 min from Bortle 6
All telescopes for the Iris Nebula · All targets for the DWARF mini