> ## Content Index > Fetch the complete content index at: https://www.dspremote.com/llms.txt > Use this file to discover other available public pages before exploring further. # Light Pollution Astrophotography: What Works From Bortle 7 - URL: https://www.dspremote.com/light-pollution-astrophotography-bortle-7/ - Published: 2026-10-21T15:00:00.000Z - Updated: 2026-10-21T15:00:00.000Z - Description: What works from a Bortle 7 backyard: the right targets, LED-proof filters, short subs and gradient removal, plus where light pollution still wins. - Author: Edward Thomas - Tags: Deep Space Blog, Astrophotography, #needs-images Yes, you can make good astrophotos from a Bortle 7 backyard, as long as you pick targets and filters that work with the sky instead of against it. Emission nebulae shot through narrowband or dual-band filters come out well from the suburbs. Faint galaxies, dust and reflection nebulae are where light pollution wins, because they need roughly 28 times more integration time than they would under a Bortle 1 sky. Below is what works from a bright sky, how to set your exposures and filters, how to clean up gradients, and where the backyard runs out of road. ## Quick facts - DSP Remote is near Animas, New Mexico, at 4,240 ft under true Bortle 1 skies. - The site averages over 286 clear nights a year. - Members control their rigs from home over a dedicated multi-dish Starlink connection. - Roof-open hours and a live all-sky camera are on our [Site Conditions page](https://www.dspremote.com/conditions/). - Piers are priced by swing diameter, from $300 a month (Small Kit) to $550 a month (Extra-Large Kit). ## Can you do astrophotography from a Bortle 7 sky? Yes. A Bortle 7 sky is bright, but it doesn't stop a camera from collecting signal. It adds noise, so the same image takes much longer. The skill of light pollution astrophotography is choosing projects where that extra time stays reasonable. A Bortle 7 sky reads around 18.0 to 18.5 magnitudes per square arcsecond on a sky quality meter. That's about 28 times brighter than a Bortle 1 sky. Our post [What Is a Bortle 1 Sky?](https://www.dspremote.com/bortle-1-sky-astrophotography/) walks through where that number comes from, and the [Bortle scale](https://en.wikipedia.org/wiki/Bortle%5Fscale?ref=dspremote.com) describes each class in detail. Plenty of well-known images are shot from city and suburban yards. They tend to have one thing in common: the target emits light in a few narrow wavelengths, and the imager filters out almost everything else. ## Which targets work best under light pollution? Emission nebulae, planetary nebulae, bright star clusters and the Moon and planets work best under light pollution. Emission and planetary nebulae glow in a few specific wavelengths (hydrogen-alpha, oxygen III and sulfur II), so a narrow filter can isolate them from sky glow. Clusters and solar system targets are bright enough that the sky barely matters. Here's a working list sorted by how well each type survives a Bortle 7 sky: | Target type | Examples | From Bortle 7 | | ------------------------------------------------------------------- | -------------------------------------------------------------------------------------------- | ----------------------------------------------- | | Hydrogen-alpha emission nebulae | Heart and Soul (IC 1805, IC 1848), North America (NGC 7000), Rosette (NGC 2237), Orion (M42) | Works well with narrowband or dual-band filters | | Supernova remnants and OIII-rich nebulae | Veil (NGC 6960, NGC 6992), Crescent (NGC 6888) | Works with narrowband, needs more OIII time | | Planetary nebulae | Dumbbell (M27), Ring (M57) | Works well, small and bright | | Globular and open clusters | M13, Double Cluster | Works in broadband, short integration | | Bright galaxy cores | Andromeda (M31), M81 and M82 | Possible, but outer arms and halos suffer | | Faint galaxies, reflection and dark nebulae, integrated flux nebula | M101 halo, Iris (NGC 7023), dust around the Pleiades | Very hard, needs a dark sky | Autumn is a good season for suburban imagers. The Heart and Soul, the Pacman (NGC 281) and the Bubble (NGC 7635) are all well placed in the evening and all respond to hydrogen-alpha. ## Do light pollution filters work with LED streetlights? Narrowband and dual-band filters work with LED lighting. Older broadband light pollution filters mostly don't. The older filters were built to block the narrow emission lines of sodium and mercury streetlights, while white LEDs spread their light across the whole visible spectrum. ![](https://storage.ghost.io/c/ac/5c/ac5c2bd9-4299-47d6-94f0-460f5567d535/content/images/2026/10/filters.png) That leaves three practical choices for a backyard imager: - A mono camera with 3 nm to 7 nm hydrogen-alpha, OIII and SII filters gives the best contrast, at the cost of a filter wheel and separate time on each channel. - A one-shot color camera with a dual-band filter (one that passes hydrogen-alpha and OIII together) is the simpler route and works well on emission nebulae. - Plain broadband imaging with no filter, or a UV/IR cut filter only, is still right for clusters and bright galaxy cores, and you correct the color in processing. A narrowband filter does nothing for galaxies and reflection nebulae. Their light is spread across the spectrum, just like the LED glow, so any filter that blocks the sky blocks the target too. ## How long should your subframes be in a light-polluted sky? Under a bright sky, your subframes can be short. Once the sky background in each frame is roughly 10 times the square of your camera's read noise (in electrons), read noise adds less than 5 percent to the total. Past that point longer subs gain you almost nothing, and only total integration time improves the image. A worked example: a modern CMOS camera like the ZWO ASI2600MC reads at roughly 1.5 electrons at its usual imaging gain. Ten times 1.5 squared is about 23 electrons of sky per pixel. From a Bortle 7 yard with a fast refractor and no filter, you can reach that in well under a minute. With a 3 nm narrowband filter the sky signal drops so far that 3 to 5 minute subs are common. Short broadband subs have side benefits at home. You lose less to a passing plane or a neighbor's porch light, guiding errors cost you fewer frames, and the data is easier to sort. The trade-off is file count, so check your disk space before a long night. ## How much more integration time does a Bortle 7 sky need? For faint broadband targets, integration time scales roughly with sky brightness. A target that comes out clean in 5 hours under a Bortle 1 sky needs about 140 hours from a Bortle 7 backyard to reach the same signal-to-noise ratio with the same gear. | Sky | Sky glow vs. Bortle 1 (approx.) | Time to match 5 hours at Bortle 1 | | -------- | ------------------------------- | --------------------------------- | | Bortle 1 | 1x | 5 hours | | Bortle 4 | 2x | 10 hours | | Bortle 5 | 7x | 35 hours | | Bortle 6 | 16x | 80 hours | | Bortle 7 | 28x | 140 hours | | Bortle 8 | 40x or more | 200 hours or more | The estimate assumes the sky is the main noise source and the target is fainter than the sky, which is true for galaxy halos and dust. It overstates the penalty for bright targets and for narrowband, where the filter has already removed most of the sky. It also leaves out the time gradients cost you in processing. Count your clear nights too. If you get 6 usable nights a month and 4 hours a night on a target, 140 hours is about six months of clear weather spent on one galaxy. Our side-by-side look at [M101 from two skies](https://www.dspremote.com/why-bortle-1-skies-transform-your-astrophotography-a-side-by-side-look-at-m101/) shows what that gap looks like on a real target. ## How do you remove light pollution gradients? You remove light pollution gradients in two places: at capture, by choosing when and where you point, and in processing, with a background extraction tool. Good flat frames come first, because a gradient tool can't separate sky glow from uncorrected vignetting and dust. At capture: - Image targets near the meridian, when they're highest and furthest from the light dome on your horizon. - Plan the night so the target is in the darkest part of your sky. If the city is to the east, shoot eastern targets late, after they've climbed. - Take fresh flats for every session, and use a dew shield to cut stray light from nearby fixtures. - Dither every few frames so stacking can reject hot pixels and walking noise. In processing, [Siril](https://siril.org/?ref=dspremote.com) (free) has a background extraction tool that samples the sky between stars and subtracts a smooth model of the glow. GraXpert, also free, does the same with an AI model, and PixInsight users have DBE. Run extraction on the linear stack, before stretching, and keep sample points off faint nebulosity so you don't subtract your target. ## What can't you fix from a light-polluted backyard? You can't filter out light pollution on broadband targets, and you can't process away noise you never had the signal to beat. Faint galaxy halos, tidal streams, reflection nebulae, dark nebulae and the integrated flux nebula all emit across the spectrum, so the only way to cut their noise is a darker sky or far more hours. The other limits are practical. Every night at home includes setup, polar alignment and teardown. Weather decides how many nights you get, and a bright Moon takes broadband off the table for a week or more each month at any site. Many imagers settle on a split. They keep a rig at home for narrowband, lunar and planetary work, and send their broadband projects to a dark site. Our earlier post on [whether remote hosting is worth it](https://www.dspremote.com/remote-telescope-hosting-vs-backyard/) runs the clear-night math on that choice. At DSP Remote, a hosted rig sits on its own custom pier under true Bortle 1 skies, with automated roll-off roofs that open and close based on conditions and time of day. You run it from home with NINA, SGP, ACP or TheSkyX. Member results are on our [Member Images page](https://www.dspremote.com/photos/). ## Frequently asked questions ### Can you do astrophotography in a Bortle 7 or 8 sky? Yes. Emission nebulae, planetary nebulae, clusters, the Moon and planets all work well from Bortle 7 or 8, especially with narrowband or dual-band filters. Faint galaxies and dust are the targets that suffer most. ### What is the best filter for light pollution? For emission nebulae, a narrowband filter (3 nm to 7 nm hydrogen-alpha, OIII or SII) or a dual-band filter for color cameras. Older broadband light pollution filters do little against white LED lighting. ### Do light pollution filters help with galaxies? Not much. Galaxies emit across the whole spectrum, the same way LED sky glow does, so a filter that blocks the sky also blocks the galaxy. Darker skies and more integration time are the only fixes. ### How long should exposures be in a light-polluted sky? Aim for a sky background of about 10 times your camera's read noise squared, in electrons. With a modern CMOS camera that's often under a minute in broadband from Bortle 7, and 3 to 5 minutes through a narrowband filter. ### How much darker is Bortle 1 than Bortle 7? About 28 times darker, based on typical sky quality meter readings. For faint broadband targets that means roughly 28 times less integration time for the same signal-to-noise ratio. ## Send your broadband projects to a Bortle 1 sky If your galaxy projects are stuck at 20 noisy hours from the backyard, keep the home rig for narrowband and put a second rig where the sky does the work. Measure your swing diameter with the calculator on our [Plans and Pricing page](https://www.dspremote.com/plans-and-pricing/), find your kit size, and reserve your pier.