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

About 7 min of total integration for a solid image, or 28 min for a showpiece. A quick look takes 2 min.

How many subs is that on the Vespera 3?

At the default 10 s sub length, 43 subs for a solid image from Bortle 6 and 30 from Bortle 3.

Does a dual-band filter help on the Hercules Cluster?

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

How long to image the Hercules Cluster with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 7 min (43 subs of 10 s) for a solid image of the Hercules Cluster. A quick look takes 2 min; a showpiece 28 min. Under a Bortle 3 rural sky the solid figure drops to 5 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 23% of the frame’s short side.

Hercules Cluster 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	2 min10 subs	5 min30 subs	15 min90 subs
Bortle 2Typical dark site	2 min10 subs	5 min30 subs	15 min90 subs
Bortle 3Rural	2 min10 subs	5 min30 subs	15 min90 subs
Bortle 4Rural / suburban transition	2 min10 subs	5 min30 subs	16 min99 subs
Bortle 5Suburban	2 min10 subs	5 min30 subs	20 min119 subs
Bortle 6Bright suburban	2 min11 subs	7 min43 subs	28 min169 subs
Bortle 7Suburban / urban transition	3 min17 subs	11 min66 subs	44 min263 subs
Bortle 8City	4 min26 subs	17 min103 subs	1 h 08 min410 subs
Bortle 9Inner city	8 min46 subs	30 min181 subs	2 h722 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 9 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 Hercules Cluster is 20′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it fills 23% 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	5 min30 subs	5 min30 subs	11 min66 subs
20 s	10 min30 subs	10 min30 subs	11 min32 subs
30 s	15 min30 subs	15 min30 subs	15 min30 subs

About the Hercules Cluster

The great northern globular, a few hundred thousand stars in a ball a third the Moon's width. Quick and always satisfying.

M13, NGC 6205 · Globular cluster in Hercules · magnitude 5.8 · 20′ · best in May, Jun, Jul. 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 Hercules Cluster with your Vespera 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Hercules Cluster 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 Hercules Cluster · All targets for the Vespera 3