How long to image the M85 with the Vaonis Vespera Pro
From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 3 h 08 min (1,126 subs of 10 s) for a solid image of the M85. A quick look takes 47 min; a showpiece 13 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 24 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 | 19 min112 subs | 1 h 14 min446 subs | 4 h 57 min1,781 subs |
| Bortle 2Typical dark site | 19 min117 subs | 1 h 18 min467 subs | 5 h 11 min1,865 subs |
| Bortle 3Rural | 21 min127 subs | 1 h 24 min506 subs | 5 h 37 min2,023 subs |
| Bortle 4Rural / suburban transition | 25 min151 subs | 1 h 40 min602 subs | 6 h 41 min2,406 subs |
| Bortle 5Suburban | 31 min189 subs | 2 h 05 min753 subs | 8 h 22 min3,012 subs |
| Bortle 6Bright suburban | 47 min282 subs | 3 h 08 min1,126 subs | 13 h4,502 subs |
| Bortle 7Suburban / urban transition | 1 h 16 min459 subs | 5 h 06 min1,835 subs | 20 h7,339 subs |
| Bortle 8City | 2 h 02 min734 subs | 8 h 09 min2,936 subs | 33 h11,744 subs |
| Bortle 9Inner city | 3 h 40 min1,322 subs | 15 h5,285 subs | 59 h21,139 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 4 h 04 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 M85 is 7′ × 5.5′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ 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, no EQ mode. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 1 h 24 min506 subs | 2 h 05 min753 subs | 5 h 06 min1,835 subs |
| 20 s | 1 h 11 min214 subs | 1 h 52 min338 subs | 4 h 53 min879 subs |
| 30 s | 1 h 07 min134 subs | 1 h 48 min217 subs | 4 h 48 min577 subs |
About the M85
A lenticular galaxy at the northern edge of the Virgo cluster, with NGC 4394 alongside.
NGC 4382 · Galaxy in Coma Berenices · magnitude 9.1 · 7′ × 5.5′ · 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
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 M85 from a Vespera Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M85 with the ZWO Seestar S50: 1 h 24 min from Bortle 6
- M85 with the ZWO Seestar S50 Pro: 1 h 32 min from Bortle 6
- M85 with the ZWO Seestar S30: 1 h 28 min from Bortle 6
- M85 with the ZWO Seestar S30 Pro: 1 h 37 min from Bortle 6
- M85 with the DwarfLab DWARF 3: 2 h 02 min from Bortle 6
- M85 with the DwarfLab DWARF mini: 1 h 24 min from Bortle 6
- M85 with the DwarfLab Draco: 1 h 09 min from Bortle 6
- M85 with the DwarfLab DWARF II: 4 h 45 min from Bortle 6
- M85 with the Vaonis Vespera II: 1 h 24 min from Bortle 6
- M85 with the Vaonis Vespera 3: 1 h 20 min from Bortle 6
- M85 with the Vaonis Vespera Pro 2: 2 h 59 min from Bortle 6
- M85 with the Unistellar eQuinox 2: 1 h 15 min from Bortle 6
- M85 with the Unistellar Odyssey: 5 h 45 min from Bortle 6
- M85 with the Celestron Origin: 22 min from Bortle 6
- M85 with the Celestron Origin Mark II: 31 min from Bortle 6
All telescopes for the M85 · All targets for the Vespera Pro