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

About 28 min of total integration for a solid image, or 1 h 53 min for a showpiece. A quick look takes 7 min.

How many subs is that on the Vespera II?

At the default 10 s sub length, 170 subs for a solid image from Bortle 6 and 73 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 28 min to 20 min.

How long to image the Lagoon Nebula with the Vaonis Vespera II

From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 28 min (170 subs of 10 s) for a solid image of the Lagoon Nebula. A quick look takes 7 min; a showpiece 1 h 53 min. Under a Bortle 3 rural sky the solid figure drops to 12 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 is just over the frame at 1.0×.

Lagoon Nebula with the Vaonis Vespera II: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	3 min16 subs	11 min64 subs	42 min254 subs
Bortle 2Typical dark site	3 min17 subs	11 min67 subs	44 min267 subs
Bortle 3Rural	3 min19 subs	12 min73 subs	48 min291 subs
Bortle 4Rural / suburban transition	4 min22 subs	15 min88 subs	58 min351 subs
Bortle 5Suburban	5 min28 subs	19 min112 subs	1 h 14 min445 subs
Bortle 6Bright suburban	7 min43 subs	28 min170 subs	1 h 53 min677 subs
Bortle 7Suburban / urban transition	12 min70 subs	47 min280 subs	3 h 06 min1,119 subs
Bortle 8City	19 min113 subs	1 h 15 min452 subs	5 h 01 min1,806 subs
Bortle 9Inner city	34 min205 subs	2 h 16 min818 subs	9 h 05 min3,270 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 37 min of run time. The Vespera II’s battery (rated about 4 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 30WOnly four hours inside; Vaonis specifies a 30 W PD source. C-to-C cable not included.
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Vaonis Vespera hygrometer sensorTriggers the built-in demister automatically; the correct dew accessory for the II.
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red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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Everything that fits the Vespera II →

How it frames

The Lagoon Nebula is 90′ × 40′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it is just over the frame at 1.0×. Point at the part you want; the edges will fall outside the frame.

Longer subs

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	12 min73 subs	19 min112 subs	47 min280 subs
20 s	11 min32 subs	17 min52 subs	45 min136 subs
30 s	15 min30 subs	17 min34 subs	45 min90 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	12 min73 subs	19 min112 subs	47 min280 subs
dual-band (Dual Band filter), clip-on	15 min89 subs	17 min101 subs	25 min152 subs

The Vespera II has no built-in dual-band filter. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar; the app detects which is fitted. 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 II

A 50 mm quadruplet on an 8 MP sensor with Vaonis’s mosaic mode for wide fields. Same optics class as the Seestar S50, four times the pixels.

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar; the app detects which is fitted.

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 IIVaonis 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 II? 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 II? 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 II