How long should I image the M88 with the Vespera 3 from a Bortle 6 sky?

About 1 h 45 min of total integration for a solid image, or 6 h 59 min for a showpiece. A quick look takes 26 min.

How many subs is that on the Vespera 3?

At the default 10 s sub length, 629 subs for a solid image from Bortle 6 and 253 from Bortle 3.

Does a dual-band filter help on the M88?

No. The M88 is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the M88 with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 1 h 45 min (629 subs of 10 s) for a solid image of the M88. A quick look takes 26 min; a showpiece 6 h 59 min. Under a Bortle 3 rural sky the solid figure drops to 42 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 8% of the frame’s short side.

M88 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	9 min54 subs	36 min216 subs	2 h 24 min864 subs
Bortle 2Typical dark site	10 min58 subs	38 min229 subs	2 h 32 min915 subs
Bortle 3Rural	11 min64 subs	42 min253 subs	2 h 48 min1,011 subs
Bortle 4Rural / suburban transition	13 min78 subs	52 min311 subs	3 h 27 min1,243 subs
Bortle 5Suburban	17 min101 subs	1 h 07 min403 subs	4 h 29 min1,612 subs
Bortle 6Bright suburban	26 min158 subs	1 h 45 min629 subs	6 h 59 min2,515 subs
Bortle 7Suburban / urban transition	44 min265 subs	2 h 57 min1,060 subs	12 h4,237 subs
Bortle 8City	1 h 12 min432 subs	4 h 48 min1,728 subs	19 h6,911 subs
Bortle 9Inner city	2 h 11 min789 subs	8 h 46 min3,154 subs	35 h12,613 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h 16 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 M88 is 7′ × 4′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it fills 8% 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	42 min253 subs	1 h 07 min403 subs	2 h 57 min1,060 subs
20 s	36 min110 subs	1 h 02 min185 subs	2 h 51 min513 subs
30 s	35 min70 subs	1 h120 subs	2 h 49 min339 subs

About the M88

A tilted spiral in the Virgo cluster with tightly wound arms.

NGC 4501 · Galaxy in Coma Berenices · magnitude 9.6 · 7′ × 4′ · 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 M88 with your Vespera 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M88 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 M88 · All targets for the Vespera 3