How long should I image the Elephant's Trunk Nebula with the Vespera 3 from a Bortle 6 sky?

About 3 h 41 min of total integration for a solid image, or 15 h for a showpiece. A quick look takes 55 min.

How many subs is that on the Vespera 3?

At the default 10 s sub length, 1,326 subs for a solid image from Bortle 6 and 480 from Bortle 3.

Does a dual-band filter help on the Elephant's Trunk Nebula?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 3 h 41 min to 2 h 14 min.

How long to image the Elephant's Trunk Nebula with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 3 h 41 min (1,326 subs of 10 s) for a solid image of the Elephant's Trunk Nebula. A quick look takes 55 min; a showpiece 15 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 20 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 1.9× wider than the frame.

Elephant's Trunk Nebula with the Vaonis Vespera 3: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	17 min100 subs	1 h 06 min398 subs	4 h 25 min1,589 subs
Bortle 2Typical dark site	18 min107 subs	1 h 11 min426 subs	4 h 44 min1,703 subs
Bortle 3Rural	20 min120 subs	1 h 20 min480 subs	5 h 20 min1,919 subs
Bortle 4Rural / suburban transition	25 min153 subs	1 h 42 min611 subs	6 h 47 min2,442 subs
Bortle 5Suburban	34 min205 subs	2 h 16 min818 subs	9 h 05 min3,270 subs
Bortle 6Bright suburban	55 min332 subs	3 h 41 min1,326 subs	15 h5,302 subs
Bortle 7Suburban / urban transition	1 h 36 min574 subs	6 h 22 min2,294 subs	25 h9,174 subs
Bortle 8City	2 h 38 min950 subs	11 h3,797 subs	42 h15,185 subs
Bortle 9Inner city	4 h 52 min1,751 subs	19 h7,002 subs	78 h28,006 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 4 h 47 min of run time. The Vespera 3’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 30WVaonis says an external bank extends sessions; 30 W PD as for the II and Pro.
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How it frames

The Elephant's Trunk Nebula is 170′ × 140′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it is 1.9× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.

Longer subs

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only; CovalENS mosaic widens the field to 4.3° × 2.4°. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	1 h 20 min480 subs	2 h 16 min818 subs	6 h 22 min2,294 subs
20 s	1 h 07 min202 subs	2 h 04 min371 subs	6 h 10 min1,109 subs
30 s	1 h 03 min127 subs	1 h 59 min239 subs	6 h 05 min731 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	1 h 20 min480 subs	2 h 16 min818 subs	6 h 22 min2,294 subs
dual-band (Dual Band filter), clip-on	1 h 31 min547 subs	1 h 48 min650 subs	3 h 04 min1,102 subs

The Vespera 3 has no built-in dual-band filter. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar. The new optical baffle is not a substitute for a CLS filter. On an emission target like this it is the single biggest upgrade you can make.

About the Elephant's Trunk Nebula

A vast, faint hydrogen cloud in Cepheus with the dark trunk winding through it. Huge, so wide scopes frame the whole thing; dual-band is essential from any lit sky.

IC 1396 · Emission nebula in Cepheus · magnitude 3.5 · 170′ × 140′ · best in Jul, Aug, Sep. 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 3

The 2026 Vespera: same 50 mm quadruplet class as the II on an 8 MP IMX585, with a 24 MP mosaic mode and 11 hours of battery. Per pixel it behaves like a Seestar S50 Pro without the built-in dual-band filter.

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only; CovalENS mosaic widens the field to 4.3° × 2.4°. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar. The new optical baffle is not a substitute for a CLS filter.

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 Elephant's Trunk Nebula with your Vespera 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Elephant's Trunk Nebula from a Vespera 3? Email it with your total time and sky to [email protected] and it goes here, credited.

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