How long should I image the Little Dumbbell with the Origin Mark II from a Bortle 6 sky?

About 17 min of total integration for a solid image, or 1 h 06 min for a showpiece. A quick look takes 4 min.

How many subs is that on the Origin Mark II?

At the default 10 s sub length, 100 subs for a solid image from Bortle 6 and 39 from Bortle 3.

Does a dual-band filter help on the Little Dumbbell?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 17 min to 9 min.

How long to image the Little Dumbbell with the Celestron Origin Mark II

From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 17 min (100 subs of 10 s) for a solid image of the Little Dumbbell. A quick look takes 4 min; a showpiece 1 h 06 min. Under a Bortle 3 rural sky the solid figure drops to 6 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 6% of the frame’s short side.

Little Dumbbell with the Celestron Origin Mark II: 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 min33 subs	22 min130 subs
Bortle 2Typical dark site	2 min10 subs	6 min35 subs	23 min138 subs
Bortle 3Rural	2 min10 subs	6 min39 subs	26 min154 subs
Bortle 4Rural / suburban transition	2 min12 subs	8 min48 subs	32 min192 subs
Bortle 5Suburban	3 min16 subs	10 min63 subs	42 min252 subs
Bortle 6Bright suburban	4 min25 subs	17 min100 subs	1 h 06 min399 subs
Bortle 7Suburban / urban transition	7 min43 subs	28 min171 subs	1 h 53 min681 subs
Bortle 8City	12 min70 subs	47 min280 subs	3 h 06 min1,117 subs
Bortle 9Inner city	21 min128 subs	1 h 25 min512 subs	5 h 41 min2,048 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 22 min of run time. The Origin Mark II’s battery (rated about 6 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 Little Dumbbell is 2.7′ × 1.8′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it fills 6% of the frame’s short side.

Longer subs

10 s auto subs (15 s with the Nebula Filter); manual 1 to 30 s on the alt-az mount, longer only with the EQ wedge, and 60 s and up needs the StarSense Autoguider too. Celestron warns the f/2.2 optics saturate quickly without the filter. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	6 min39 subs	10 min63 subs	28 min171 subs
15 s	8 min30 subs	10 min42 subs	28 min113 subs
30 s	15 min30 subs	15 min30 subs	28 min57 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	6 min39 subs	10 min63 subs	28 min171 subs
dual-band (Nebula Filter), drawer	6 min39 subs	8 min46 subs	13 min79 subs

The Origin Mark II has no built-in dual-band filter. Filter drawer takes 1.25-inch or 2-inch filters, including dual-band; Celestron sells an optional Nebula Filter. On an emission target like this it is the single biggest upgrade you can make.

About the Little Dumbbell

A small, bright-per-pixel planetary in Perseus. Dual-band makes the two lobes and the faint wings much easier.

M76, NGC 650 · Planetary nebula in Perseus · magnitude 10.1 · 2.7′ × 1.8′ · best in Sep, Oct, Nov. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.

About the Celestron Origin Mark II

The Origin Mark II (late 2025): the same 6-inch f/2.2 RASA with an 8 MP IMX678 in place of the original 6 MP IMX178. Smaller pixels for finer detail, a quieter sensor, and still the fastest system here by a wide margin.

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 Origin Mark IICelestron store Direct Amazon UK Amazon USThe Celestron 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 Little Dumbbell with your Origin Mark II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Little Dumbbell from a Origin Mark 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 Little Dumbbell · All targets for the Origin Mark II