How long should I image the M54 with the Vespera 3 from a Bortle 6 sky?

About 27 min of total integration for a solid image, or 1 h 49 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, 164 subs for a solid image from Bortle 6 and 72 from Bortle 3.

Does a dual-band filter help on the M54?

No. The M54 is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the M54 with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 27 min (164 subs of 10 s) for a solid image of the M54. A quick look takes 7 min; a showpiece 1 h 49 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 14% of the frame’s short side.

M54 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 min250 subs
Bortle 2Typical dark site	3 min17 subs	11 min66 subs	44 min263 subs
Bortle 3Rural	3 min18 subs	12 min72 subs	48 min286 subs
Bortle 4Rural / suburban transition	4 min22 subs	14 min86 subs	57 min343 subs
Bortle 5Suburban	5 min28 subs	18 min109 subs	1 h 12 min433 subs
Bortle 6Bright suburban	7 min41 subs	27 min164 subs	1 h 49 min654 subs
Bortle 7Suburban / urban transition	11 min68 subs	45 min269 subs	2 h 59 min1,075 subs
Bortle 8City	18 min109 subs	1 h 12 min433 subs	4 h 48 min1,729 subs
Bortle 9Inner city	33 min196 subs	2 h 10 min781 subs	8 h 40 min3,123 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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red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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How it frames

The M54 is 12′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it fills 14% 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 min109 subs	45 min269 subs
20 s	11 min32 subs	17 min50 subs	43 min131 subs
30 s	15 min30 subs	16 min33 subs	43 min86 subs

About the M54

A globular that actually belongs to the Sagittarius Dwarf galaxy being eaten by the Milky Way. Low from the north.

NGC 6715 · Globular cluster in Sagittarius · magnitude 7.6 · 12′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.

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 M54 with your Vespera 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M54 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 M54 · All targets for the Vespera 3