How long to image the M106 with the ZWO Seestar S50
From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 1 h 05 min (390 subs of 10 s) for a solid image of the M106. A quick look takes 16 min; a showpiece 4 h 20 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 44% 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 | 5 min33 subs | 22 min132 subs | 1 h 28 min527 subs |
| Bortle 2Typical dark site | 6 min35 subs | 23 min140 subs | 1 h 33 min559 subs |
| Bortle 3Rural | 6 min39 subs | 26 min155 subs | 1 h 43 min619 subs |
| Bortle 4Rural / suburban transition | 8 min48 subs | 32 min191 subs | 2 h 07 min764 subs |
| Bortle 5Suburban | 10 min63 subs | 41 min249 subs | 2 h 46 min995 subs |
| Bortle 6Bright suburban | 16 min98 subs | 1 h 05 min390 subs | 4 h 20 min1,559 subs |
| Bortle 7Suburban / urban transition | 27 min165 subs | 1 h 50 min659 subs | 7 h 19 min2,636 subs |
| Bortle 8City | 45 min270 subs | 2 h 59 min1,077 subs | 12 h4,307 subs |
| Bortle 9Inner city | 1 h 22 min492 subs | 5 h 28 min1,968 subs | 22 h7,871 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 24 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.)
- 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.
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 M106 is 19′ × 8′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 44% 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 min155 subs | 41 min249 subs | 1 h 50 min659 subs |
| 20 s | 22 min67 subs | 38 min114 subs | 1 h 46 min319 subs |
| 30 s | 21 min42 subs | 37 min74 subs | 1 h 45 min210 subs |
| 60 s | 30 min30 subs | 35 min36 subs | 1 h 44 min104 subs |
Leave the dual-band filter out for the M106. It is a galaxy, 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 M106
A big, bright spiral with anomalous red arms driven by its black hole. Dual-band brings the extra arms out.
NGC 4258 · Galaxy in Canes Venatici · magnitude 8.4 · 19′ × 8′ · 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 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 M106 from a Seestar S50? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M106 with the ZWO Seestar S50 Pro: 1 h 11 min from Bortle 6
- M106 with the ZWO Seestar S30: 1 h 08 min from Bortle 6
- M106 with the ZWO Seestar S30 Pro: 1 h 15 min from Bortle 6
- M106 with the DwarfLab DWARF 3: 1 h 34 min from Bortle 6
- M106 with the DwarfLab DWARF mini: 1 h 05 min from Bortle 6
- M106 with the DwarfLab Draco: 53 min from Bortle 6
- M106 with the DwarfLab DWARF II: 3 h 42 min from Bortle 6
- M106 with the Vaonis Vespera II: 1 h 05 min from Bortle 6
- M106 with the Vaonis Vespera Pro: 2 h 25 min from Bortle 6
- M106 with the Vaonis Vespera 3: 1 h 02 min from Bortle 6
- M106 with the Vaonis Vespera Pro 2: 2 h 19 min from Bortle 6
- M106 with the Unistellar eQuinox 2: 59 min from Bortle 6
- M106 with the Unistellar Odyssey: 4 h 31 min from Bortle 6
- M106 with the Celestron Origin: 17 min from Bortle 6
- M106 with the Celestron Origin Mark II: 24 min from Bortle 6
All telescopes for the M106 · All targets for the Seestar S50