How long to image the Thor's Helmet with the Vaonis Vespera II
From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 10 h (3,727 subs of 10 s) for a solid image of the Thor's Helmet. A quick look takes 2 h 35 min; a showpiece 41 h. Under a Bortle 3 rural sky the solid figure drops to 3 h 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 9% 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 | 46 min277 subs | 3 h 05 min1,108 subs | 12 h4,429 subs |
| Bortle 2Typical dark site | 49 min297 subs | 3 h 18 min1,188 subs | 13 h4,750 subs |
| Bortle 3Rural | 56 min335 subs | 3 h 43 min1,340 subs | 15 h5,359 subs |
| Bortle 4Rural / suburban transition | 1 h 11 min428 subs | 4 h 45 min1,709 subs | 19 h6,834 subs |
| Bortle 5Suburban | 1 h 36 min574 subs | 6 h 22 min2,293 subs | 25 h9,171 subs |
| Bortle 6Bright suburban | 2 h 35 min932 subs | 10 h3,727 subs | 41 h14,905 subs |
| Bortle 7Suburban / urban transition | 4 h 29 min1,615 subs | 18 h6,458 subs | 72 h25,831 subs |
| Bortle 8City | 7 h 26 min2,675 subs | 30 h10,699 subs | 120+ h42,795 subs |
| Bortle 9Inner city | 14 h4,936 subs | 55 h19,744 subs | 220+ h78,975 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 13 h of run time. That is more than one night: over 2 nights, about 6 h 44 min each. The Vespera II’s battery is rated at about 4 h, 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 30WOnly four hours inside; Vaonis specifies a 30 W PD source. C-to-C cable not included.
- Vaonis Vespera hygrometer sensorTriggers the built-in demister automatically; the correct dew accessory for the II.
- 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 Vespera II →
How it frames
The Thor's Helmet is 8′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it fills 9% of the frame’s short side.
Longer subs
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 3 h 43 min1,340 subs | 6 h 22 min2,293 subs | 18 h6,458 subs |
| 20 s | 3 h 06 min559 subs | 5 h 45 min1,035 subs | 17 h3,118 subs |
| 30 s | 2 h 54 min348 subs | 5 h 32 min665 subs | 17 h2,054 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| No filter | 3 h 43 min1,340 subs | 6 h 22 min2,293 subs | 18 h6,458 subs |
| dual-band (Dual Band filter), clip-on | 4 h 16 min1,535 subs | 5 h 04 min1,826 subs | 8 h 37 min3,102 subs |
The Vespera II has no built-in dual-band filter. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar; the app detects which is fitted. On an emission target like this it is the single biggest upgrade you can make.
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 Vaonis Vespera II
A 50 mm quadruplet on an 8 MP sensor with Vaonis’s mosaic mode for wide fields. Same optics class as the Seestar S50, four times the pixels.
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar; the app detects which is fitted.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 30 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 Vespera II? 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 3: 7 h 41 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 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 Vespera II