How long should I image the Bubble Nebula with the Vespera 3 from a Bortle 6 sky?

About 4 h 24 min of total integration for a solid image, or 18 h for a showpiece. A quick look takes 1 h 06 min.

How many subs is that on the Vespera 3?

At the default 10 s sub length, 1,586 subs for a solid image from Bortle 6 and 569 from Bortle 3.

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

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 4 h 24 min to 2 h 39 min.

How long to image the Bubble Nebula with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 4 h 24 min (1,586 subs of 10 s) for a solid image of the Bubble Nebula. A quick look takes 1 h 06 min; a showpiece 18 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 35 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 17% of the frame’s short side.

Bubble 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	20 min118 subs	1 h 18 min470 subs	5 h 13 min1,879 subs
Bortle 2Typical dark site	21 min126 subs	1 h 24 min504 subs	5 h 36 min2,016 subs
Bortle 3Rural	24 min143 subs	1 h 35 min569 subs	6 h 19 min2,276 subs
Bortle 4Rural / suburban transition	30 min182 subs	2 h 01 min726 subs	8 h 04 min2,904 subs
Bortle 5Suburban	41 min244 subs	2 h 42 min975 subs	11 h3,900 subs
Bortle 6Bright suburban	1 h 06 min397 subs	4 h 24 min1,586 subs	18 h6,343 subs
Bortle 7Suburban / urban transition	1 h 55 min688 subs	7 h 38 min2,750 subs	31 h10,998 subs
Bortle 8City	3 h 10 min1,140 subs	13 h4,557 subs	51 h18,225 subs
Bortle 9Inner city	5 h 50 min2,103 subs	23 h8,410 subs	93 h33,639 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 5 h 44 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 Bubble Nebula is 15′ × 8′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it fills 17% 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 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 35 min569 subs	2 h 42 min975 subs	7 h 38 min2,750 subs
20 s	1 h 20 min239 subs	2 h 27 min442 subs	7 h 23 min1,329 subs
30 s	1 h 15 min150 subs	2 h 22 min285 subs	7 h 18 min876 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	1 h 35 min569 subs	2 h 42 min975 subs	7 h 38 min2,750 subs
dual-band (Dual Band filter), clip-on	1 h 48 min646 subs	2 h 08 min770 subs	3 h 39 min1,313 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 Bubble Nebula

A wind-blown bubble in a larger hydrogen cloud beside M52. Small; the bubble itself needs a scope with reach.

NGC 7635, Caldwell 11 · Emission nebula in Cassiopeia · magnitude 10.0 · 15′ × 8′ · best in Aug, Sep, Oct. 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 Bubble 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 Bubble Nebula from a Vespera 3? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Bubble Nebula · All targets for the Vespera 3