How long should I image the Lagoon Nebula with the Vespera Pro 2 from a Bortle 6 sky?

About 1 h of total integration for a solid image, or 4 h for a showpiece. A quick look takes 15 min.

How many subs is that on the Vespera Pro 2?

At the default 10 s sub length, 360 subs for a solid image from Bortle 6 and 165 from Bortle 3.

Does a dual-band filter help on the Lagoon Nebula?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 1 h to 46 min.

How long to image the Lagoon Nebula with the Vaonis Vespera Pro 2

From a Bortle 6 suburban sky, the Vaonis Vespera Pro 2 needs about 1 h (360 subs of 10 s) for a solid image of the Lagoon Nebula. A quick look takes 15 min; a showpiece 4 h. Under a Bortle 3 rural sky the solid figure drops to 27 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 only just fits, at 91% of the short side.

Lagoon Nebula with the Vaonis Vespera Pro 2: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	6 min37 subs	24 min146 subs	1 h 37 min584 subs
Bortle 2Typical dark site	6 min39 subs	25 min153 subs	1 h 42 min610 subs
Bortle 3Rural	7 min42 subs	27 min165 subs	1 h 50 min660 subs
Bortle 4Rural / suburban transition	8 min49 subs	32 min195 subs	2 h 10 min780 subs
Bortle 5Suburban	10 min61 subs	40 min243 subs	2 h 42 min971 subs
Bortle 6Bright suburban	15 min90 subs	1 h360 subs	4 h1,440 subs
Bortle 7Suburban / urban transition	24 min146 subs	1 h 37 min583 subs	6 h 29 min2,332 subs
Bortle 8City	39 min233 subs	2 h 35 min930 subs	10 h3,718 subs
Bortle 9Inner city	1 h 10 min418 subs	4 h 38 min1,669 subs	19 h6,674 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 18 min of run time. The Vespera Pro 2’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 30WExternal bank extends the 11 h battery.
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How it frames

The Lagoon Nebula is 90′ × 40′ across. The Vespera Pro 2 frames 1.65° × 1.65° at 1.68″ per pixel, so it only just fits, at 91% of the short side. Centre it carefully: there is no room to crop back afterwards.

Longer subs

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only; CovalENS mosaic gives 3.2° × 3.2° at 50 MP. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	27 min165 subs	40 min243 subs	1 h 37 min583 subs
20 s	24 min71 subs	37 min110 subs	1 h 33 min280 subs
30 s	22 min45 subs	35 min71 subs	1 h 32 min184 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	27 min165 subs	40 min243 subs	1 h 37 min583 subs
dual-band (Dual Band filter), clip-on	36 min216 subs	40 min240 subs	57 min344 subs

The Vespera Pro 2 has no built-in dual-band filter. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar. On an emission target like this it is the single biggest upgrade you can make.

About the Lagoon Nebula

The showpiece emission nebula of the summer Milky Way, bright enough to catch its core in minutes. Pair it with the Trifid in one wide frame.

M8, NGC 6523 · Emission nebula in Sagittarius · magnitude 6.0 · 90′ × 40′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.

Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.

About the Vaonis Vespera Pro 2

The square-sensor 2026 Vespera with 2 µm pixels. Sharper than the Vespera 3 on small targets and correspondingly slower per pixel; the 12.5 MP square frame suits galaxies and planetaries.

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only; CovalENS mosaic gives 3.2° × 3.2° at 50 MP. 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.

Where to buy the Vespera Pro 2Vaonis store Direct Amazon UK Amazon USThe Vaonis store link is a plain link; the others are affiliate links. As an Amazon Associate I earn from qualifying purchases, at no cost to you.

Imaged the Lagoon Nebula with your Vespera Pro 2? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Lagoon Nebula from a Vespera Pro 2? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Lagoon Nebula · All targets for the Vespera Pro 2