How long to image the Thor's Helmet with the DwarfLab DWARF 3
From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 7 h 41 min (1,845 subs of 15 s with the built-in dual-band filter) for a solid image of the Thor's Helmet. A quick look takes 1 h 55 min; a showpiece 31 h. Under a Bortle 3 rural sky the solid figure drops to 4 h 33 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 8% 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 | 1 h 04 min255 subs | 4 h 15 min1,019 subs | 17 h4,074 subs |
| Bortle 2Typical dark site | 1 h 05 min261 subs | 4 h 21 min1,044 subs | 17 h4,176 subs |
| Bortle 3Rural | 1 h 08 min273 subs | 4 h 33 min1,092 subs | 18 h4,368 subs |
| Bortle 4Rural / suburban transition | 1 h 15 min302 subs | 5 h 02 min1,208 subs | 20 h4,832 subs |
| Bortle 5Suburban | 1 h 27 min349 subs | 5 h 48 min1,393 subs | 23 h5,569 subs |
| Bortle 6Bright suburban | 1 h 55 min462 subs | 7 h 41 min1,845 subs | 31 h7,377 subs |
| Bortle 7Suburban / urban transition | 2 h 49 min677 subs | 11 h2,706 subs | 45 h10,821 subs |
| Bortle 8City | 4 h 13 min1,011 subs | 17 h4,043 subs | 67 h16,169 subs |
| Bortle 9Inner city | 7 h 11 min1,724 subs | 29 h6,894 subs | 110+ h27,575 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 9 h 59 min of run time. That is more than one night: over 2 nights, about 5 h each. The DWARF 3’s battery is rated at about 5 h 30 min, less near freezing, so each night needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a January night.)
- 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.
- 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 DWARF 3 →
How it frames
The Thor's Helmet is 8′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it fills 8% 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 | 4 h 33 min1,092 subs | 5 h 48 min1,393 subs | 11 h2,706 subs |
| 30 s | 3 h 49 min459 subs | 5 h 05 min610 subs | 11 h1,266 subs |
| 60 s | 3 h 28 min208 subs | 4 h 43 min283 subs | 10 h612 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| Astro (no light-pollution filter) | 4 h 45 min1,141 subs | 8 h 50 min2,122 subs | 27 h6,411 subs |
| dual-band | 4 h 33 min1,092 subs | 5 h 48 min1,393 subs | 11 h2,706 subs |
About the Thor's Helmet
A Wolf-Rayet bubble with wings, strong in OIII. Small and faint; dual-band is essential and a bigger scope helps.
NGC 2359 · Emission nebula in Canis Major · magnitude 11.5 · 8′ · best in Dec, Jan, Feb. 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 Thor's Helmet from a DWARF 3? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Thor's Helmet with the ZWO Seestar S50: 6 h 17 min from Bortle 6
- Thor's Helmet with the ZWO Seestar S50 Pro: 7 h 04 min from Bortle 6
- Thor's Helmet with the ZWO Seestar S30: 7 h 24 min from Bortle 6
- Thor's Helmet with the ZWO Seestar S30 Pro: 7 h 38 min from Bortle 6
- Thor's Helmet with the DwarfLab DWARF mini: 6 h 11 min from Bortle 6
- Thor's Helmet with the DwarfLab Draco: 4 h 58 min from Bortle 6
- Thor's Helmet with the DwarfLab DWARF II: 36 h from Bortle 6
- Thor's Helmet with the Vaonis Vespera II: 10 h from Bortle 6
- Thor's Helmet with the Vaonis Vespera Pro: 23 h from Bortle 6
- Thor's Helmet with the Vaonis Vespera 3: 9 h 53 min from Bortle 6
- Thor's Helmet with the Vaonis Vespera Pro 2: 22 h from Bortle 6
- Thor's Helmet with the Unistellar eQuinox 2: 9 h 31 min from Bortle 6
- Thor's Helmet with the Unistellar Odyssey: 44 h from Bortle 6
- Thor's Helmet with the Celestron Origin: 2 h 44 min from Bortle 6
- Thor's Helmet with the Celestron Origin Mark II: 3 h 44 min from Bortle 6
All telescopes for the Thor's Helmet · All targets for the DWARF 3