How long to image the Pleiades with the DwarfLab DWARF 3
From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 3 h 55 min (939 subs of 15 s) for a solid image of the Pleiades. A quick look takes 59 min; a showpiece 16 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 18 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 is just over the frame at 1.1×.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 16 min63 subs | 1 h 03 min251 subs | 4 h 10 min1,002 subs |
| Bortle 2Typical dark site | 17 min68 subs | 1 h 08 min272 subs | 4 h 31 min1,086 subs |
| Bortle 3Rural | 19 min78 subs | 1 h 18 min312 subs | 5 h 11 min1,246 subs |
| Bortle 4Rural / suburban transition | 26 min103 subs | 1 h 42 min409 subs | 6 h 48 min1,634 subs |
| Bortle 5Suburban | 35 min141 subs | 2 h 20 min562 subs | 9 h 22 min2,248 subs |
| Bortle 6Bright suburban | 59 min235 subs | 3 h 55 min939 subs | 16 h3,756 subs |
| Bortle 7Suburban / urban transition | 1 h 44 min415 subs | 6 h 54 min1,657 subs | 28 h6,628 subs |
| Bortle 8City | 2 h 53 min693 subs | 12 h2,772 subs | 46 h11,087 subs |
| Bortle 9Inner city | 5 h 22 min1,288 subs | 21 h5,150 subs | 86 h20,598 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 5 h 05 min of run time. The DWARF 3’s battery is rated at about 5 h 30 min, less near freezing, so the session needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a November night.)
- USB-C PD power bank 20000mAh 18W18 W PD input and it runs while charging; needs a C-to-C cable for PD.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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Everything that fits the DWARF 3 →
How it frames
The Pleiades is 110′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it is just over the frame at 1.1×. Point at the part you want; the edges will fall outside the frame.
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 length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 15 s | 1 h 18 min312 subs | 2 h 20 min562 subs | 6 h 54 min1,657 subs |
| 30 s | 1 h 12 min145 subs | 2 h 15 min271 subs | 6 h 49 min818 subs |
| 60 s | 1 h 10 min70 subs | 2 h 12 min133 subs | 6 h 46 min407 subs |
Leave the dual-band filter out for the Pleiades. It is a reflection nebula, 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 10 times slower.
About the Pleiades
The stars take seconds. The blue reflection nebulosity around them is faint and needs hours from any sky, and no filter helps because it is starlight, not emission.
M45, Seven Sisters · Reflection nebula in Taurus · magnitude 1.6 · 110′ · best in Oct, Nov, Dec. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Reflection nebulae are starlight scattered by dust, so they are broadband and blue. A dual-band filter removes almost all of it; do not use one. These are among the faintest structures a smart scope can attempt and the figures run long. A dark sky matters more here than for any other type, and the Moon must be down.
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.
Have an image of the Pleiades from a DWARF 3? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Pleiades with the ZWO Seestar S50: 2 h 42 min from Bortle 6
- Pleiades with the ZWO Seestar S50 Pro: 2 h 57 min from Bortle 6
- Pleiades with the ZWO Seestar S30: 2 h 50 min from Bortle 6
- Pleiades with the ZWO Seestar S30 Pro: 3 h 08 min from Bortle 6
- Pleiades with the DwarfLab DWARF mini: 2 h 41 min from Bortle 6
- Pleiades with the DwarfLab Draco: 2 h 13 min from Bortle 6
- Pleiades with the DwarfLab DWARF II: 9 h 16 min from Bortle 6
- Pleiades with the Vaonis Vespera II: 2 h 42 min from Bortle 6
- Pleiades with the Vaonis Vespera Pro: 6 h 03 min from Bortle 6
- Pleiades with the Vaonis Vespera 3: 2 h 35 min from Bortle 6
- Pleiades with the Vaonis Vespera Pro 2: 5 h 46 min from Bortle 6
- Pleiades with the Unistellar eQuinox 2: 2 h 28 min from Bortle 6
- Pleiades with the Unistellar Odyssey: 11 h from Bortle 6
- Pleiades with the Celestron Origin: 43 min from Bortle 6
- Pleiades with the Celestron Origin Mark II: 59 min from Bortle 6
All telescopes for the Pleiades · All targets for the DWARF 3