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

About 2 h 30 min of total integration for a solid image, or 9 h 59 min for a showpiece. A quick look takes 37 min.

How many subs is that on the Vespera Pro?

At the default 10 s sub length, 899 subs for a solid image from Bortle 6 and 389 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 30 min to 1 h 50 min.

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

From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 2 h 30 min (899 subs of 10 s) for a solid image of the Trifid Nebula. A quick look takes 37 min; a showpiece 9 h 59 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 05 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 29% of the frame’s short side.

Trifid Nebula with the Vaonis Vespera Pro: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	14 min85 subs	56 min339 subs	3 h 46 min1,354 subs
Bortle 2Typical dark site	15 min89 subs	59 min356 subs	3 h 57 min1,423 subs
Bortle 3Rural	16 min98 subs	1 h 05 min389 subs	4 h 19 min1,553 subs
Bortle 4Rural / suburban transition	19 min117 subs	1 h 18 min467 subs	5 h 11 min1,868 subs
Bortle 5Suburban	25 min148 subs	1 h 39 min592 subs	6 h 34 min2,367 subs
Bortle 6Bright suburban	37 min225 subs	2 h 30 min899 subs	9 h 59 min3,593 subs
Bortle 7Suburban / urban transition	1 h 02 min371 subs	4 h 07 min1,482 subs	16 h5,927 subs
Bortle 8City	1 h 39 min597 subs	6 h 38 min2,388 subs	27 h9,552 subs
Bortle 9Inner city	3 h1,081 subs	12 h4,321 subs	48 h17,282 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 15 min of run time. The Vespera Pro’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 30WExtends the 11 h battery; 30 W PD per Vaonis.
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How it frames

The Trifid Nebula is 28′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 29% 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	1 h 05 min389 subs	1 h 39 min592 subs	4 h 07 min1,482 subs
20 s	54 min162 subs	1 h 28 min264 subs	3 h 56 min709 subs
30 s	50 min101 subs	1 h 24 min169 subs	3 h 53 min466 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	1 h 05 min389 subs	1 h 39 min592 subs	4 h 07 min1,482 subs
dual-band (Dual Band filter), clip-on	1 h 24 min507 subs	1 h 35 min569 subs	2 h 20 min842 subs

The Vespera Pro 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

The square-sensor Vespera with 2 µm pixels. Higher resolution than the II, and correspondingly slower per pixel: expect around double the time for the same per-pixel SNR. Run-out in 2026 and replaced by the Vespera Pro 2.

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.

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? 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? 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