How long should I image the M70 with the Vespera 3 from a Bortle 6 sky?

About 16 min of total integration for a solid image, or 1 h 03 min for a showpiece. A quick look takes 4 min.

How many subs is that on the Vespera 3?

At the default 10 s sub length, 95 subs for a solid image from Bortle 6 and 47 from Bortle 3.

Does a dual-band filter help on the M70?

No. The M70 is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the M70 with the Vaonis Vespera 3

From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 16 min (95 subs of 10 s) for a solid image of the M70. A quick look takes 4 min; a showpiece 1 h 03 min. Under a Bortle 3 rural sky the solid figure drops to 8 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 9% of the frame’s short side.

M70 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 min11 subs	7 min43 subs	28 min169 subs
Bortle 2Typical dark site	2 min11 subs	7 min44 subs	29 min175 subs
Bortle 3Rural	2 min12 subs	8 min47 subs	31 min187 subs
Bortle 4Rural / suburban transition	2 min14 subs	9 min54 subs	36 min216 subs
Bortle 5Suburban	3 min17 subs	11 min66 subs	44 min263 subs
Bortle 6Bright suburban	4 min24 subs	16 min95 subs	1 h 03 min377 subs
Bortle 7Suburban / urban transition	6 min38 subs	25 min149 subs	1 h 39 min593 subs
Bortle 8City	10 min59 subs	39 min233 subs	2 h 35 min930 subs
Bortle 9Inner city	17 min103 subs	1 h 09 min412 subs	4 h 35 min1,648 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 20 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.
Amazon UK Amazon US
red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
Amazon UK Amazon US

Affiliate links: the retailer pays us a small commission and you pay the same price. These are search links to the named product, not endorsements of a particular listing; check the listing matches your model.

Everything that fits the Vespera 3 →

How it frames

The M70 is 8′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ per pixel, so it fills 9% 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	8 min47 subs	11 min66 subs	25 min149 subs
20 s	10 min30 subs	10 min31 subs	24 min72 subs
30 s	15 min30 subs	15 min30 subs	24 min48 subs

About the M70

M69's near twin two degrees east, a compact globular in the same low field.

NGC 6681 · Globular cluster in Sagittarius · magnitude 7.9 · 8′ · 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 M70 with your Vespera 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M70 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 M70 · All targets for the Vespera 3