How long should I image the M105 with the Vespera 3 from a Bortle 6 sky?

About 57 min of total integration for a solid image, or 3 h 48 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, 342 subs for a solid image from Bortle 6 and 147 from Bortle 3.

Does a dual-band filter help on the M105?

No. The M105 is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the M105 with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 57 min (342 subs of 10 s) for a solid image of the M105. A quick look takes 14 min; a showpiece 3 h 48 min. Under a Bortle 3 rural sky the solid figure drops to 24 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 6% of the frame’s short side.

M105 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 min32 subs	21 min128 subs	1 h 25 min511 subs
Bortle 2Typical dark site	6 min34 subs	22 min135 subs	1 h 29 min537 subs
Bortle 3Rural	6 min37 subs	24 min147 subs	1 h 38 min587 subs
Bortle 4Rural / suburban transition	7 min45 subs	29 min177 subs	1 h 58 min707 subs
Bortle 5Suburban	9 min57 subs	37 min225 subs	2 h 30 min898 subs
Bortle 6Bright suburban	14 min86 subs	57 min342 subs	3 h 48 min1,366 subs
Bortle 7Suburban / urban transition	24 min142 subs	1 h 34 min565 subs	6 h 16 min2,258 subs
Bortle 8City	38 min228 subs	2 h 32 min911 subs	10 h3,642 subs
Bortle 9Inner city	1 h 09 min413 subs	4 h 35 min1,649 subs	18 h6,594 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 14 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 M105 is 5.4′ × 4.8′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it fills 6% 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	24 min147 subs	37 min225 subs	1 h 34 min565 subs
20 s	22 min65 subs	34 min104 subs	1 h 31 min274 subs
30 s	21 min42 subs	34 min68 subs	1 h 30 min181 subs

About the M105

An elliptical in the Leo I group, with NGC 3384 and NGC 3389 forming a tight trio.

NGC 3379 · Galaxy in Leo · magnitude 9.3 · 5.4′ × 4.8′ · best in Feb, Mar, Apr. 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 M105 with your Vespera 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M105 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 M105 · All targets for the Vespera 3