How long to image the Crab Nebula with the ZWO Seestar S50 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S50 Pro needs about 31 min (187 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Crab Nebula. A quick look takes 8 min; a showpiece 2 h 04 min. Under a Bortle 3 rural sky the solid figure drops to 24 min. At Bortle 6 the limit is a mix of skyglow and read noise. 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 | 6 min36 subs | 24 min142 subs | 1 h 34 min565 subs |
| Bortle 2Typical dark site | 6 min36 subs | 24 min143 subs | 1 h 35 min571 subs |
| Bortle 3Rural | 6 min37 subs | 24 min146 subs | 1 h 37 min581 subs |
| Bortle 4Rural / suburban transition | 6 min38 subs | 25 min152 subs | 1 h 41 min607 subs |
| Bortle 5Suburban | 7 min41 subs | 27 min162 subs | 1 h 48 min647 subs |
| Bortle 6Bright suburban | 8 min47 subs | 31 min187 subs | 2 h 04 min747 subs |
| Bortle 7Suburban / urban transition | 10 min59 subs | 39 min234 subs | 2 h 36 min936 subs |
| Bortle 8City | 13 min77 subs | 51 min308 subs | 3 h 25 min1,231 subs |
| Bortle 9Inner city | 19 min117 subs | 1 h 17 min465 subs | 5 h 10 min1,858 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 40 min of run time. The Seestar S50 Pro’s battery (rated about 9 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 PD power bank 20000mAh 30WAccepts 12 V 3 A PD, so a 30 W bank tops up the 10,000 mAh cell while imaging.
- Seestar S50 Pro dew shieldDew heater is built in; a shield adds margin on damp nights. Check the listing says S50 Pro.
- 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 Seestar S50 Pro →
How it frames
The Crab Nebula is 6′ × 4′ across. The Seestar S50 Pro frames 2.45° × 1.38° at 2.30″ per pixel, so it fills 7% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 24 min146 subs | 27 min162 subs | 39 min234 subs |
| 20 s | 20 min59 subs | 22 min67 subs | 34 min104 subs |
| 30 s | 18 min36 subs | 21 min42 subs | 33 min66 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 31 min32 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 19 min116 subs | 28 min170 subs | 1 h 08 min406 subs |
| dual-band (LP filter) | 24 min146 subs | 27 min162 subs | 39 min234 subs |
About the Crab Nebula
The remains of the supernova of 1054, a tangle of filaments around a pulsar. Small but bright enough for a good result in an evening.
M1, NGC 1952 · Supernova remnant in Taurus · magnitude 8.4 · 6′ × 4′ · best in Nov, Dec, Jan. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Supernova remnants are emission-line objects, strong in both hydrogen-alpha and OIII, and their filaments are thin, so pixel scale matters as much as aperture. A dual-band filter is essential from any lit sky and still helps under a dark one. These are long-integration targets; plan on several sessions and stack across nights.
About the ZWO Seestar S50 Pro
The S50 optics at 260 mm on an 8 MP 1/1.2-inch sensor: a wider, taller field, four times the pixels, and 60 s subs in EQ mode. Per pixel it is a whisker slower than the S50 because of the longer focal length; the long subs make it the better dark-site scope.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters on the telephoto camera.
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 Crab Nebula from a Seestar S50 Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Crab Nebula with the ZWO Seestar S50: 28 min from Bortle 6
- Crab Nebula with the ZWO Seestar S30: 31 min from Bortle 6
- Crab Nebula with the ZWO Seestar S30 Pro: 33 min from Bortle 6
- Crab Nebula with the DwarfLab DWARF 3: 37 min from Bortle 6
- Crab Nebula with the DwarfLab DWARF mini: 28 min from Bortle 6
- Crab Nebula with the DwarfLab Draco: 22 min from Bortle 6
- Crab Nebula with the DwarfLab DWARF II: 2 h 08 min from Bortle 6
- Crab Nebula with the Vaonis Vespera II: 38 min from Bortle 6
- Crab Nebula with the Vaonis Vespera Pro: 1 h 25 min from Bortle 6
- Crab Nebula with the Vaonis Vespera 3: 37 min from Bortle 6
- Crab Nebula with the Vaonis Vespera Pro 2: 1 h 21 min from Bortle 6
- Crab Nebula with the Unistellar eQuinox 2: 34 min from Bortle 6
- Crab Nebula with the Unistellar Odyssey: 2 h 32 min from Bortle 6
- Crab Nebula with the Celestron Origin: 10 min from Bortle 6
- Crab Nebula with the Celestron Origin Mark II: 14 min from Bortle 6
All telescopes for the Crab Nebula · All targets for the Seestar S50 Pro