How long to image the M65 with the Vaonis Vespera II

From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 52 min (313 subs of 10 s) for a solid image of the M65. A quick look takes 13 min; a showpiece 3 h 28 min. Under a Bortle 3 rural sky the solid figure drops to 22 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 12% of the frame’s short side.

M65 with the Vaonis Vespera II: 10 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site5 min29 subs19 min114 subs1 h 16 min455 subs
Bortle 2Typical dark site5 min30 subs20 min120 subs1 h 20 min479 subs
Bortle 3Rural5 min33 subs22 min132 subs1 h 27 min525 subs
Bortle 4Rural / suburban transition7 min40 subs27 min160 subs1 h 46 min637 subs
Bortle 5Suburban8 min51 subs34 min204 subs2 h 16 min815 subs
Bortle 6Bright suburban13 min79 subs52 min313 subs3 h 28 min1,250 subs
Bortle 7Suburban / urban transition22 min130 subs1 h 27 min520 subs5 h 46 min2,079 subs
Bortle 8City35 min211 subs2 h 20 min842 subs9 h 21 min3,366 subs
Bortle 9Inner city1 h 04 min382 subs4 h 15 min1,528 subs17 h6,111 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 08 min of run time. The Vespera II’s battery (rated about 4 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.)

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How it frames

The M65 is 10′ × 3′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it fills 12% 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 lengthBortle 3Bortle 5Bortle 7
10 s22 min132 subs34 min204 subs1 h 27 min520 subs
20 s19 min58 subs31 min94 subs1 h 24 min252 subs
30 s18 min37 subs30 min61 subs1 h 23 min166 subs

About the M65

One of the Leo Triplet, an inclined spiral with a bright core. Fits in a frame with M66 and NGC 3628.

NGC 3623 · Galaxy in Leo · magnitude 9.3 · 10′ × 3′ · best in Feb, Mar, Apr. 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 II

A 50 mm quadruplet on an 8 MP sensor with Vaonis’s mosaic mode for wide fields. Same optics class as the Seestar S50, four times the pixels.

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; the app detects which is fitted.

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 M65 with your Vespera II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M65 from a Vespera II? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the M65 · All targets for the Vespera II