How long to image the M58 with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 3 h 01 min (1,087 subs of 10 s) for a solid image of the M58. A quick look takes 45 min; a showpiece 12 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 13 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 4% 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 | 16 min95 subs | 1 h 03 min379 subs | 4 h 12 min1,513 subs |
| Bortle 2Typical dark site | 17 min100 subs | 1 h 07 min400 subs | 4 h 27 min1,600 subs |
| Bortle 3Rural | 18 min111 subs | 1 h 13 min441 subs | 4 h 54 min1,764 subs |
| Bortle 4Rural / suburban transition | 23 min136 subs | 1 h 30 min541 subs | 6 h2,163 subs |
| Bortle 5Suburban | 29 min175 subs | 1 h 56 min699 subs | 7 h 46 min2,796 subs |
| Bortle 6Bright suburban | 45 min272 subs | 3 h 01 min1,087 subs | 12 h4,347 subs |
| Bortle 7Suburban / urban transition | 1 h 16 min457 subs | 5 h 04 min1,826 subs | 20 h7,303 subs |
| Bortle 8City | 2 h 04 min744 subs | 8 h 16 min2,974 subs | 33 h11,893 subs |
| Bortle 9Inner city | 3 h 46 min1,356 subs | 15 h5,421 subs | 60 h21,682 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 55 min of run time. The Seestar S30 Pro’s battery (rated about 5 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 10000mAh 5V 3A5 V 3 A input and it runs while charging.
- Seestar S30 Pro dew shieldActive anti-dew is built in; a shield adds margin. The S30 Pro front differs from the S30, so check the listing.
- 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 S30 Pro →
How it frames
The M58 is 6′ × 5′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 4% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 1 h 13 min441 subs | 1 h 56 min699 subs | 5 h 04 min1,826 subs |
| 20 s | 1 h 02 min187 subs | 1 h 45 min316 subs | 4 h 53 min879 subs |
| 30 s | 58 min117 subs | 1 h 41 min203 subs | 4 h 49 min579 subs |
| 60 s | 54 min55 subs | 1 h 37 min98 subs | 4 h 45 min286 subs |
Leave the dual-band filter out for the M58. 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 M58
A barred spiral in the Virgo cluster, one of the brighter members. Frame it with M59 and M60.
NGC 4579 · Galaxy in Virgo · magnitude 9.7 · 6′ × 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 ZWO Seestar S30 Pro
The S30 optics upgraded to a quadruplet in front of an 8 MP IMX585. Same speed per pixel as the S30, four times the pixels, so you can crop hard.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. 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 M58 from a Seestar S30 Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M58 with the ZWO Seestar S50: 2 h 36 min from Bortle 6
- M58 with the ZWO Seestar S50 Pro: 2 h 51 min from Bortle 6
- M58 with the ZWO Seestar S30: 2 h 44 min from Bortle 6
- M58 with the DwarfLab DWARF 3: 3 h 47 min from Bortle 6
- M58 with the DwarfLab DWARF mini: 2 h 36 min from Bortle 6
- M58 with the DwarfLab Draco: 2 h 08 min from Bortle 6
- M58 with the DwarfLab DWARF II: 8 h 53 min from Bortle 6
- M58 with the Vaonis Vespera II: 2 h 36 min from Bortle 6
- M58 with the Vaonis Vespera Pro: 5 h 50 min from Bortle 6
- M58 with the Vaonis Vespera 3: 2 h 29 min from Bortle 6
- M58 with the Vaonis Vespera Pro 2: 5 h 33 min from Bortle 6
- M58 with the Unistellar eQuinox 2: 2 h 21 min from Bortle 6
- M58 with the Unistellar Odyssey: 11 h from Bortle 6
- M58 with the Celestron Origin: 41 min from Bortle 6
- M58 with the Celestron Origin Mark II: 57 min from Bortle 6
All telescopes for the M58 · All targets for the Seestar S30 Pro