How long to image the M14 with the DwarfLab DWARF 3

From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 33 min (133 subs of 15 s) for a solid image of the M14. A quick look takes 8 min; a showpiece 2 h 12 min. Under a Bortle 3 rural sky the solid figure drops to 14 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 11% of the frame’s short side.

M14 with the DwarfLab DWARF 3: 15 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site3 min13 subs12 min50 subs49 min197 subs
Bortle 2Typical dark site3 min13 subs13 min52 subs52 min207 subs
Bortle 3Rural4 min15 subs14 min57 subs57 min227 subs
Bortle 4Rural / suburban transition4 min18 subs17 min69 subs1 h 08 min274 subs
Bortle 5Suburban5 min22 subs22 min87 subs1 h 27 min348 subs
Bortle 6Bright suburban8 min34 subs33 min133 subs2 h 12 min530 subs
Bortle 7Suburban / urban transition14 min55 subs55 min220 subs3 h 39 min878 subs
Bortle 8City22 min89 subs1 h 29 min355 subs5 h 54 min1,418 subs
Bortle 9Inner city40 min161 subs2 h 41 min643 subs11 h2,570 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 43 min of run time. The DWARF 3’s battery (rated about 5 h 30 min) 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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Everything that fits the DWARF 3 →

How it frames

The M14 is 11′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it fills 11% of the frame’s short side.

Longer subs

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Time for a solid image by sub length:

Sub lengthBortle 3Bortle 5Bortle 7
15 s14 min57 subs22 min87 subs55 min220 subs
30 s15 min30 subs21 min43 subs54 min109 subs
60 s30 min30 subs30 min30 subs54 min54 subs

Leave the dual-band filter out for the M14. It is a globular cluster, and it shines right across the spectrum. A dual-band filter keeps two emission lines and throws the rest away, so most of the light you came for is being stopped along with the sky. From a Bortle 6 sky it would be roughly 9 times slower.

About the M14

A fainter, more distant globular in Ophiuchus. Takes longer than its neighbours to resolve.

NGC 6402 · Globular cluster in Ophiuchus · magnitude 7.6 · 11′ · 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 DwarfLab DWARF 3

Small pixels on a 35 mm f/4.3 lens give a sharper image than its aperture suggests, and EQ mode with 60 s subs makes it the read-noise winner in dark skies.

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Three built-in filters: VIS, Astro (430 to 690 nm) and dual-band Hα 656 nm / OIII 501 nm.

Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 15 s and 60 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 M14 with your DWARF 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M14 from a DWARF 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 M14 · All targets for the DWARF 3