How long to image the M78 with the ZWO Seestar S50
From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 1 h 03 min (377 subs of 10 s) for a solid image of the M78. A quick look takes 16 min; a showpiece 4 h 11 min. Under a Bortle 3 rural sky the solid figure drops to 26 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 19% 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 | 6 min35 subs | 23 min138 subs | 1 h 32 min551 subs |
| Bortle 2Typical dark site | 6 min37 subs | 24 min145 subs | 1 h 37 min580 subs |
| Bortle 3Rural | 7 min40 subs | 26 min159 subs | 1 h 46 min636 subs |
| Bortle 4Rural / suburban transition | 8 min49 subs | 32 min193 subs | 2 h 08 min770 subs |
| Bortle 5Suburban | 10 min62 subs | 41 min246 subs | 2 h 44 min983 subs |
| Bortle 6Bright suburban | 16 min95 subs | 1 h 03 min377 subs | 4 h 11 min1,506 subs |
| Bortle 7Suburban / urban transition | 26 min157 subs | 1 h 44 min626 subs | 6 h 57 min2,503 subs |
| Bortle 8City | 42 min254 subs | 2 h 49 min1,013 subs | 11 h4,050 subs |
| Bortle 9Inner city | 1 h 17 min460 subs | 5 h 06 min1,838 subs | 20 h7,349 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 22 min of run time. The Seestar S50’s battery (rated about 6 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, and 30% off the battery for a December night.)
- USB-C power bank 20000mAh 5V 3AThe S50 draws 5 V 3 A over USB-C and runs while charging; no PD needed.
- Seestar S50 dew shieldThe built-in heater copes with most nights; a shield helps in heavy dew and blocks stray light.
- 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.
Affiliate links: the retailer pays us a small commission and you pay the same price. These are search links to the named product, not endorsements of a particular listing; check the listing matches your model.
Everything that fits the Seestar S50 →
How it frames
The M78 is 8′ × 6′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 19% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 26 min159 subs | 41 min246 subs | 1 h 44 min626 subs |
| 20 s | 23 min70 subs | 38 min113 subs | 1 h 41 min303 subs |
| 30 s | 22 min44 subs | 36 min73 subs | 1 h 40 min200 subs |
| 60 s | 30 min30 subs | 35 min36 subs | 1 h 39 min99 subs |
Leave the dual-band filter out for the M78. It is a reflection nebula, and it shines right across the spectrum. A dual-band filter keeps two emission lines and throws the rest away, so most of the light you came for is being stopped along with the sky. From a Bortle 6 sky it would be roughly 12 times slower.
About the M78
The brightest reflection nebula in the sky, blue dust lit by young stars in Orion's belt. No filter; it is starlight.
NGC 2068 · Reflection nebula in Orion · magnitude 8.3 · 8′ × 6′ · best in Nov, Dec, Jan. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Reflection nebulae are starlight scattered by dust, so they are broadband and blue. A dual-band filter removes almost all of it; do not use one. These are among the faintest structures a smart scope can attempt and the figures run long. A dark sky matters more here than for any other type, and the Moon must be down.
About the ZWO Seestar S50
The scope that made smart astrophotography mainstream. 50 mm triplet, 2 MP sensor, dual-band filter on a wheel. Alt-Az stacking at 10 s, EQ mode unlocks 60 s. Out of production since 2026 and replaced by the S50 Pro, but there are a great many in use.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Built-in dual-band light-pollution filter, switchable in the app.
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 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 M78 from a Seestar S50? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M78 with the ZWO Seestar S50 Pro: 1 h 09 min from Bortle 6
- M78 with the ZWO Seestar S30: 1 h 06 min from Bortle 6
- M78 with the ZWO Seestar S30 Pro: 1 h 13 min from Bortle 6
- M78 with the DwarfLab DWARF 3: 1 h 31 min from Bortle 6
- M78 with the DwarfLab DWARF mini: 1 h 02 min from Bortle 6
- M78 with the DwarfLab Draco: 52 min from Bortle 6
- M78 with the DwarfLab DWARF II: 3 h 32 min from Bortle 6
- M78 with the Vaonis Vespera II: 1 h 03 min from Bortle 6
- M78 with the Vaonis Vespera Pro: 2 h 20 min from Bortle 6
- M78 with the Vaonis Vespera 3: 1 h from Bortle 6
- M78 with the Vaonis Vespera Pro 2: 2 h 13 min from Bortle 6
- M78 with the Unistellar eQuinox 2: 56 min from Bortle 6
- M78 with the Unistellar Odyssey: 4 h 16 min from Bortle 6
- M78 with the Celestron Origin: 17 min from Bortle 6
- M78 with the Celestron Origin Mark II: 23 min from Bortle 6
All telescopes for the M78 · All targets for the Seestar S50