How long should I image the Whirlpool Galaxy with the Vespera 3 from a Bortle 6 sky?

About 56 min of total integration for a solid image, or 3 h 44 min for a showpiece. A quick look takes 14 min.

How many subs is that on the Vespera 3?

At the default 10 s sub length, 336 subs for a solid image from Bortle 6 and 138 from Bortle 3.

Does a dual-band filter help on the Whirlpool Galaxy?

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

How long to image the Whirlpool Galaxy with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 56 min (336 subs of 10 s) for a solid image of the Whirlpool Galaxy. A quick look takes 14 min; a showpiece 3 h 44 min. Under a Bortle 3 rural sky the solid figure drops to 23 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 13% of the frame’s short side.

Whirlpool Galaxy 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	5 min30 subs	20 min118 subs	1 h 18 min471 subs
Bortle 2Typical dark site	5 min32 subs	21 min125 subs	1 h 23 min498 subs
Bortle 3Rural	6 min35 subs	23 min138 subs	1 h 31 min549 subs
Bortle 4Rural / suburban transition	7 min42 subs	28 min168 subs	1 h 52 min671 subs
Bortle 5Suburban	9 min55 subs	36 min217 subs	2 h 24 min866 subs
Bortle 6Bright suburban	14 min84 subs	56 min336 subs	3 h 44 min1,342 subs
Bortle 7Suburban / urban transition	23 min141 subs	1 h 34 min563 subs	6 h 15 min2,251 subs
Bortle 8City	38 min229 subs	2 h 33 min916 subs	10 h3,662 subs
Bortle 9Inner city	1 h 09 min417 subs	4 h 38 min1,668 subs	19 h6,671 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 13 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 Whirlpool Galaxy is 11′ × 7′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it fills 13% 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	23 min138 subs	36 min217 subs	1 h 34 min563 subs
20 s	20 min60 subs	33 min100 subs	1 h 31 min273 subs
30 s	19 min38 subs	32 min65 subs	1 h 30 min180 subs

About the Whirlpool Galaxy

The classic face-on spiral with its companion tugging at one arm. Small in a smart scope but bright; the arms appear within an hour, the tidal bridge needs several.

M51, NGC 5194 · Galaxy in Canes Venatici · magnitude 8.4 · 11′ × 7′ · best in Mar, Apr, May. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

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

Have an image of the Whirlpool Galaxy 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 Whirlpool Galaxy · All targets for the Vespera 3