How long to image the M4 with the Vaonis Vespera Pro
From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 2 h 46 min (998 subs of 10 s) for a solid image of the M4. A quick look takes 42 min; a showpiece 11 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 11 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 37% 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 | 16 min94 subs | 1 h 02 min373 subs | 4 h 09 min1,492 subs |
| Bortle 2Typical dark site | 16 min99 subs | 1 h 05 min393 subs | 4 h 21 min1,569 subs |
| Bortle 3Rural | 18 min108 subs | 1 h 11 min429 subs | 4 h 46 min1,714 subs |
| Bortle 4Rural / suburban transition | 22 min130 subs | 1 h 26 min517 subs | 5 h 44 min2,066 subs |
| Bortle 5Suburban | 27 min164 subs | 1 h 49 min656 subs | 7 h 17 min2,624 subs |
| Bortle 6Bright suburban | 42 min250 subs | 2 h 46 min998 subs | 11 h3,992 subs |
| Bortle 7Suburban / urban transition | 1 h 09 min413 subs | 4 h 35 min1,650 subs | 18 h6,599 subs |
| Bortle 8City | 1 h 51 min666 subs | 7 h 24 min2,662 subs | 30 h10,647 subs |
| Bortle 9Inner city | 3 h 21 min1,206 subs | 13 h4,821 subs | 54 h19,281 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 36 min of run time. The Vespera Pro’s battery (rated about 11 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 20000mAh 30WExtends the 11 h battery; 30 W PD per Vaonis.
- 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 Vespera Pro →
How it frames
The M4 is 36′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 37% 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 | 1 h 11 min429 subs | 1 h 49 min656 subs | 4 h 35 min1,650 subs |
| 20 s | 59 min179 subs | 1 h 37 min293 subs | 4 h 23 min789 subs |
| 30 s | 55 min111 subs | 1 h 33 min187 subs | 4 h 19 min519 subs |
About the M4
The loose globular next to Antares. Low in the sky from the UK, so image it near transit.
NGC 6121 · Globular cluster in Scorpius · magnitude 5.9 · 36′ · best in May, Jun, Jul. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.
About the Vaonis Vespera Pro
The square-sensor Vespera with 2 µm pixels. Higher resolution than the II, and correspondingly slower per pixel: expect around double the time for the same per-pixel SNR. Run-out in 2026 and replaced by the Vespera Pro 2.
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.
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 M4 from a Vespera Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M4 with the ZWO Seestar S50: 1 h 14 min from Bortle 6
- M4 with the ZWO Seestar S50 Pro: 1 h 21 min from Bortle 6
- M4 with the ZWO Seestar S30: 1 h 18 min from Bortle 6
- M4 with the ZWO Seestar S30 Pro: 1 h 26 min from Bortle 6
- M4 with the DwarfLab DWARF 3: 1 h 48 min from Bortle 6
- M4 with the DwarfLab DWARF mini: 1 h 14 min from Bortle 6
- M4 with the DwarfLab Draco: 1 h 01 min from Bortle 6
- M4 with the DwarfLab DWARF II: 4 h 14 min from Bortle 6
- M4 with the Vaonis Vespera II: 1 h 14 min from Bortle 6
- M4 with the Vaonis Vespera 3: 1 h 11 min from Bortle 6
- M4 with the Vaonis Vespera Pro 2: 2 h 39 min from Bortle 6
- M4 with the Unistellar eQuinox 2: 1 h 07 min from Bortle 6
- M4 with the Unistellar Odyssey: 5 h 11 min from Bortle 6
- M4 with the Celestron Origin: 20 min from Bortle 6
- M4 with the Celestron Origin Mark II: 27 min from Bortle 6