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

About 2 h 23 min of total integration for a solid image, or 9 h 31 min for a showpiece. A quick look takes 36 min.

How many subs is that on the Vespera Pro 2?

At the default 10 s sub length, 857 subs for a solid image from Bortle 6 and 367 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 2 h 23 min to 1 h 44 min.

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

From a Bortle 6 suburban sky, the Vaonis Vespera Pro 2 needs about 2 h 23 min (857 subs of 10 s) for a solid image of the Trifid Nebula. A quick look takes 36 min; a showpiece 9 h 31 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 01 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 28% of the frame’s short side.

Trifid 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	13 min80 subs	53 min319 subs	3 h 32 min1,275 subs
Bortle 2Typical dark site	14 min84 subs	56 min336 subs	3 h 43 min1,341 subs
Bortle 3Rural	15 min92 subs	1 h 01 min367 subs	4 h 04 min1,466 subs
Bortle 4Rural / suburban transition	18 min111 subs	1 h 14 min442 subs	4 h 55 min1,768 subs
Bortle 5Suburban	23 min141 subs	1 h 34 min562 subs	6 h 15 min2,248 subs
Bortle 6Bright suburban	36 min215 subs	2 h 23 min857 subs	9 h 31 min3,425 subs
Bortle 7Suburban / urban transition	59 min355 subs	3 h 56 min1,417 subs	16 h5,667 subs
Bortle 8City	1 h 35 min572 subs	6 h 21 min2,287 subs	25 h9,148 subs
Bortle 9Inner city	2 h 53 min1,036 subs	12 h4,143 subs	46 h16,572 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 05 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 Trifid Nebula is 28′ across. The Vespera Pro 2 frames 1.65° × 1.65° at 1.68″ per pixel, so it fills 28% 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; 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	1 h 01 min367 subs	1 h 34 min562 subs	3 h 56 min1,417 subs
20 s	51 min154 subs	1 h 24 min252 subs	3 h 46 min679 subs
30 s	48 min96 subs	1 h 20 min161 subs	3 h 43 min446 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	1 h 01 min367 subs	1 h 34 min562 subs	3 h 56 min1,417 subs
dual-band (Dual Band filter), clip-on	1 h 19 min474 subs	1 h 29 min534 subs	2 h 12 min795 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 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 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.

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Imaged the Trifid 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 Trifid 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 Trifid Nebula · All targets for the Vespera Pro 2