How long should I image the Centaurus A with the Vespera 3 from a Bortle 6 sky?

About 39 min of total integration for a solid image, or 2 h 37 min for a showpiece. A quick look takes 10 min.

How many subs is that on the Vespera 3?

At the default 10 s sub length, 236 subs for a solid image from Bortle 6 and 97 from Bortle 3.

Does a dual-band filter help on the Centaurus A?

No. The Centaurus A is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the Centaurus A with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 39 min (236 subs of 10 s) for a solid image of the Centaurus A. A quick look takes 10 min; a showpiece 2 h 37 min. Under a Bortle 3 rural sky the solid figure drops to 16 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 30% of the frame’s short side.

Centaurus A 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	3 min21 subs	14 min83 subs	55 min332 subs
Bortle 2Typical dark site	4 min22 subs	15 min88 subs	58 min351 subs
Bortle 3Rural	4 min25 subs	16 min97 subs	1 h 04 min386 subs
Bortle 4Rural / suburban transition	5 min30 subs	20 min118 subs	1 h 19 min472 subs
Bortle 5Suburban	6 min38 subs	25 min152 subs	1 h 41 min608 subs
Bortle 6Bright suburban	10 min59 subs	39 min236 subs	2 h 37 min941 subs
Bortle 7Suburban / urban transition	16 min99 subs	1 h 06 min394 subs	4 h 23 min1,576 subs
Bortle 8City	27 min161 subs	1 h 47 min641 subs	7 h 07 min2,562 subs
Bortle 9Inner city	49 min292 subs	3 h 14 min1,166 subs	13 h4,664 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 51 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 Centaurus A is 26′ × 20′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it fills 30% 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	16 min97 subs	25 min152 subs	1 h 06 min394 subs
20 s	14 min43 subs	23 min70 subs	1 h 04 min191 subs
30 s	15 min30 subs	23 min46 subs	1 h 03 min126 subs

About the Centaurus A

A giant elliptical with a thick dust band across it, the brightest radio galaxy in the sky. A southern-hemisphere showpiece.

NGC 5128, Caldwell 77 · Galaxy in Centaurus · magnitude 6.8 · 26′ × 20′ · best in Mar, Apr, May. Low or below the horizon from northern Europe; best from the southern US southwards.

Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.

Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.

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.

Where to buy the Vespera 3Vaonis store Direct Amazon UK Amazon USThe Vaonis store link is a plain link; the others are affiliate links. As an Amazon Associate I earn from qualifying purchases, at no cost to you.

Imaged the Centaurus A with your Vespera 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Centaurus A 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 Centaurus A · All targets for the Vespera 3