How long to image the M100 with the Vaonis Vespera Pro 2
From a Bortle 6 suburban sky, the Vaonis Vespera Pro 2 needs about 4 h 59 min (1,792 subs of 10 s) for a solid image of the M100. A quick look takes 1 h 15 min; a showpiece 20 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 08 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 7% 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 | 28 min168 subs | 1 h 51 min669 subs | 7 h 25 min2,673 subs |
| Bortle 2Typical dark site | 29 min176 subs | 1 h 57 min703 subs | 7 h 48 min2,811 subs |
| Bortle 3Rural | 32 min192 subs | 2 h 08 min768 subs | 8 h 32 min3,072 subs |
| Bortle 4Rural / suburban transition | 39 min232 subs | 2 h 34 min927 subs | 10 h3,705 subs |
| Bortle 5Suburban | 49 min295 subs | 3 h 16 min1,177 subs | 13 h4,708 subs |
| Bortle 6Bright suburban | 1 h 15 min448 subs | 4 h 59 min1,792 subs | 20 h7,168 subs |
| Bortle 7Suburban / urban transition | 2 h 03 min741 subs | 8 h 14 min2,964 subs | 33 h11,855 subs |
| Bortle 8City | 3 h 19 min1,196 subs | 13 h4,784 subs | 53 h19,133 subs |
| Bortle 9Inner city | 6 h 01 min2,166 subs | 24 h8,664 subs | 96 h34,654 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 6 h 28 min of run time. The Vespera Pro 2’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 30WExternal bank extends the 11 h battery.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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How it frames
The M100 is 7′ × 6′ across. The Vespera Pro 2 frames 1.65° × 1.65° at 1.68″ per pixel, so it fills 7% 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; CovalENS mosaic gives 3.2° × 3.2° at 50 MP. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 2 h 08 min768 subs | 3 h 16 min1,177 subs | 8 h 14 min2,964 subs |
| 20 s | 1 h 47 min323 subs | 2 h 56 min527 subs | 7 h 53 min1,420 subs |
| 30 s | 1 h 40 min201 subs | 2 h 49 min338 subs | 7 h 46 min933 subs |
About the M100
A grand-design spiral in Coma Berenices, one of the biggest in the Virgo cluster.
NGC 4321 · Galaxy in Coma Berenices · magnitude 9.3 · 7′ × 6′ · best in Mar, Apr, May. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.
Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.
About the Vaonis Vespera Pro 2
The square-sensor 2026 Vespera with 2 µm pixels. Sharper than the Vespera 3 on small targets and correspondingly slower per pixel; the 12.5 MP square frame suits galaxies and planetaries.
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only; CovalENS mosaic gives 3.2° × 3.2° at 50 MP. 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 M100 from a Vespera Pro 2? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M100 with the ZWO Seestar S50: 2 h 20 min from Bortle 6
- M100 with the ZWO Seestar S50 Pro: 2 h 33 min from Bortle 6
- M100 with the ZWO Seestar S30: 2 h 27 min from Bortle 6
- M100 with the ZWO Seestar S30 Pro: 2 h 42 min from Bortle 6
- M100 with the DwarfLab DWARF 3: 3 h 24 min from Bortle 6
- M100 with the DwarfLab DWARF mini: 2 h 19 min from Bortle 6
- M100 with the DwarfLab Draco: 1 h 55 min from Bortle 6
- M100 with the DwarfLab DWARF II: 7 h 58 min from Bortle 6
- M100 with the Vaonis Vespera II: 2 h 20 min from Bortle 6
- M100 with the Vaonis Vespera Pro: 5 h 13 min from Bortle 6
- M100 with the Vaonis Vespera 3: 2 h 14 min from Bortle 6
- M100 with the Unistellar eQuinox 2: 2 h 06 min from Bortle 6
- M100 with the Unistellar Odyssey: 9 h 43 min from Bortle 6
- M100 with the Celestron Origin: 37 min from Bortle 6
- M100 with the Celestron Origin Mark II: 51 min from Bortle 6
All telescopes for the M100 · All targets for the Vespera Pro 2