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

About 9 h 52 min of total integration for a solid image, or 39 h for a showpiece. A quick look takes 2 h 28 min.

How many subs is that on the Vespera Pro 2?

At the default 10 s sub length, 3,552 subs for a solid image from Bortle 6 and 1,414 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 9 h 52 min to 6 h 49 min.

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

From a Bortle 6 suburban sky, the Vaonis Vespera Pro 2 needs about 9 h 52 min (3,552 subs of 10 s) for a solid image of the Bubble Nebula. A quick look takes 2 h 28 min; a showpiece 39 h. Under a Bortle 3 rural sky the solid figure drops to 3 h 56 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 15% of the frame’s short side.

Bubble 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	50 min302 subs	3 h 21 min1,206 subs	13 h4,821 subs
Bortle 2Typical dark site	53 min320 subs	3 h 33 min1,278 subs	14 h5,109 subs
Bortle 3Rural	59 min354 subs	3 h 56 min1,414 subs	16 h5,654 subs
Bortle 4Rural / suburban transition	1 h 13 min436 subs	4 h 51 min1,744 subs	19 h6,975 subs
Bortle 5Suburban	1 h 34 min567 subs	6 h 18 min2,267 subs	25 h9,068 subs
Bortle 6Bright suburban	2 h 28 min888 subs	9 h 52 min3,552 subs	39 h14,205 subs
Bortle 7Suburban / urban transition	4 h 10 min1,500 subs	17 h5,998 subs	67 h23,992 subs
Bortle 8City	6 h 48 min2,450 subs	27 h9,797 subs	110+ h39,188 subs
Bortle 9Inner city	12 h4,475 subs	50 h17,899 subs	200+ h71,596 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 13 h of run time. That is more than one night: over 2 nights, about 6 h 25 min each. The Vespera Pro 2’s battery (rated about 11 h) should cover each night; 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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red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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How it frames

The Bubble Nebula is 15′ × 8′ across. The Vespera Pro 2 frames 1.65° × 1.65° at 1.68″ per pixel, so it fills 15% 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	3 h 56 min1,414 subs	6 h 18 min2,267 subs	17 h5,998 subs
20 s	3 h 12 min578 subs	5 h 35 min1,005 subs	16 h2,870 subs
30 s	2 h 58 min357 subs	5 h 20 min641 subs	16 h1,885 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	3 h 56 min1,414 subs	6 h 18 min2,267 subs	17 h5,998 subs
dual-band (Dual Band filter), clip-on	5 h1,801 subs	5 h 44 min2,062 subs	8 h 54 min3,205 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 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 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 Bubble 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 Bubble 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 Bubble Nebula · All targets for the Vespera Pro 2