How long should I image the M5 with the Vespera Pro from a Bortle 6 sky?

About 23 min of total integration for a solid image, or 1 h 30 min for a showpiece. A quick look takes 6 min.

How many subs is that on the Vespera Pro?

At the default 10 s sub length, 136 subs for a solid image from Bortle 6 and 70 from Bortle 3.

Does a dual-band filter help on the M5?

No. The M5 is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the M5 with the Vaonis Vespera Pro

From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 23 min (136 subs of 10 s) for a solid image of the M5. A quick look takes 6 min; a showpiece 1 h 30 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 24% of the frame’s short side.

M5 with the Vaonis Vespera Pro: 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	11 min64 subs	42 min253 subs
Bortle 2Typical dark site	3 min17 subs	11 min66 subs	44 min262 subs
Bortle 3Rural	3 min18 subs	12 min70 subs	46 min279 subs
Bortle 4Rural / suburban transition	3 min20 subs	13 min80 subs	53 min319 subs
Bortle 5Suburban	4 min24 subs	16 min96 subs	1 h 04 min383 subs
Bortle 6Bright suburban	6 min34 subs	23 min136 subs	1 h 30 min541 subs
Bortle 7Suburban / urban transition	9 min53 subs	35 min211 subs	2 h 20 min842 subs
Bortle 8City	14 min82 subs	54 min327 subs	3 h 38 min1,308 subs
Bortle 9Inner city	24 min144 subs	1 h 36 min576 subs	6 h 24 min2,303 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 29 min of run time. The Vespera Pro’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 30WExtends the 11 h battery; 30 W PD per Vaonis.
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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 M5 is 23′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 24% 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, no EQ mode. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	12 min70 subs	16 min96 subs	35 min211 subs
20 s	10 min31 subs	15 min44 subs	34 min102 subs
30 s	15 min30 subs	15 min30 subs	33 min67 subs

About the M5

A bright, slightly elliptical globular in Serpens that rivals M13 and resolves into stars quickly.

NGC 5904 · Globular cluster in Serpens · magnitude 5.7 · 23′ · best in Apr, May, Jun. 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 Pro

The square-sensor Vespera with 2 µm pixels. Higher resolution than the II, and correspondingly slower per pixel: expect around double the time for the same per-pixel SNR. Run-out in 2026 and replaced by the Vespera Pro 2.

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar.

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.

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Imaged the M5 with your Vespera Pro? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M5 from a Vespera Pro? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the M5 · All targets for the Vespera Pro