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

About 1 h 07 min of total integration for a solid image, or 4 h 28 min for a showpiece. A quick look takes 17 min.

How many subs is that on the Vespera II?

At the default 10 s sub length, 402 subs for a solid image from Bortle 6 and 159 from Bortle 3.

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

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 1 h 07 min to 44 min.

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

From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 1 h 07 min (402 subs of 10 s) for a solid image of the Trifid Nebula. A quick look takes 17 min; a showpiece 4 h 28 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 33% of the frame’s short side.

Trifid 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	6 min34 subs	23 min136 subs	1 h 30 min542 subs
Bortle 2Typical dark site	6 min36 subs	24 min144 subs	1 h 36 min574 subs
Bortle 3Rural	7 min40 subs	26 min159 subs	1 h 46 min636 subs
Bortle 4Rural / suburban transition	8 min50 subs	33 min197 subs	2 h 11 min786 subs
Bortle 5Suburban	11 min64 subs	43 min256 subs	2 h 51 min1,024 subs
Bortle 6Bright suburban	17 min101 subs	1 h 07 min402 subs	4 h 28 min1,606 subs
Bortle 7Suburban / urban transition	28 min170 subs	1 h 53 min680 subs	7 h 33 min2,717 subs
Bortle 8City	46 min278 subs	3 h 05 min1,111 subs	12 h4,441 subs
Bortle 9Inner city	1 h 25 min508 subs	5 h 38 min2,030 subs	23 h8,117 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 27 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 Trifid Nebula is 28′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it fills 33% of the frame’s short side.

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	26 min159 subs	43 min256 subs	1 h 53 min680 subs
20 s	23 min69 subs	39 min117 subs	1 h 49 min329 subs
30 s	21 min43 subs	38 min76 subs	1 h 48 min217 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	26 min159 subs	43 min256 subs	1 h 53 min680 subs
dual-band (Dual Band filter), clip-on	31 min189 subs	36 min219 subs	58 min348 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 Trifid Nebula

Red emission, blue reflection and dark lanes in one object. Shoot it without a filter to keep the blue, or dual-band for the red.

M20, NGC 6514 · Emission nebula in Sagittarius · magnitude 6.3 · 28′ · 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 Trifid 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 Trifid 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 Trifid Nebula · All targets for the Vespera II