How long should I image the M94 with the Vespera 3 from a Bortle 6 sky?

About 27 min of total integration for a solid image, or 1 h 48 min for a showpiece. A quick look takes 7 min.

How many subs is that on the Vespera 3?

At the default 10 s sub length, 162 subs for a solid image from Bortle 6 and 72 from Bortle 3.

Does a dual-band filter help on the M94?

No. The M94 is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the M94 with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 27 min (162 subs of 10 s) for a solid image of the M94. A quick look takes 7 min; a showpiece 1 h 48 min. Under a Bortle 3 rural sky the solid figure drops to 12 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.

M94 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 min16 subs	10 min63 subs	42 min252 subs
Bortle 2Typical dark site	3 min17 subs	11 min66 subs	44 min264 subs
Bortle 3Rural	3 min18 subs	12 min72 subs	48 min287 subs
Bortle 4Rural / suburban transition	4 min22 subs	14 min86 subs	57 min343 subs
Bortle 5Suburban	4 min27 subs	18 min108 subs	1 h 12 min431 subs
Bortle 6Bright suburban	7 min41 subs	27 min162 subs	1 h 48 min648 subs
Bortle 7Suburban / urban transition	11 min67 subs	44 min266 subs	2 h 57 min1,062 subs
Bortle 8City	18 min107 subs	1 h 11 min426 subs	4 h 44 min1,704 subs
Bortle 9Inner city	32 min193 subs	2 h 08 min769 subs	8 h 32 min3,074 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 35 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 M94 is 11′ × 9′ 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	12 min72 subs	18 min108 subs	44 min266 subs
20 s	11 min32 subs	17 min50 subs	43 min129 subs
30 s	15 min30 subs	16 min33 subs	42 min85 subs

About the M94

A galaxy with a blazing inner ring and a very faint outer one. The core arrives fast; the outer ring is a long-integration project.

NGC 4736, Cat’s Eye Galaxy · Galaxy in Canes Venatici · magnitude 8.2 · 11′ × 9′ · 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 M94 with your Vespera 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M94 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 M94 · All targets for the Vespera 3