More than the internet suggests, and less than the marketing does. A realistic target list by sky brightness, and why some objects barely care about light pollution at all.

The standard advice for suburban astrophotographers is to drive somewhere darker. It is good advice and most people cannot act on it on a Tuesday.

So here is the more useful question: given the sky you actually have, above the house you actually live in, what is worth pointing a camera at?

The answer is better than the forums imply. It is also not “everything”, and knowing which side of that line a target sits on will save you several wasted nights.

Bortle, briefly

The Bortle scale runs 1 (nothing but stars) to 9 (inner city). Most suburban gardens within reach of a large city are 6 or 7. Outer suburbs and small towns are 5. A flat in Delhi, São Paulo, London or Los Angeles is 8 or 9 — and the scale travels: a Bortle 7 sky behaves the same way in Manila as it does in Manchester.

If you do not know yours, look it up on a light pollution map rather than guessing — people consistently guess their own sky as darker than it is, because eyes adapt and memory is generous.

What matters for imaging is not the number itself but a single physical fact: light pollution adds background, and background brings noise. It does not dim your target. The photons from the galaxy arrive exactly as they always did. They just arrive on top of a bright, noisy floor, and separating them from it takes proportionally more integration time.

That has a direct consequence. Light pollution costs you time, not targets — until the time required becomes absurd.

The one thing that changes everything

Emission nebulae emit at specific wavelengths. Hydrogen alpha at 656nm, oxygen III at 500nm, sulphur II at 672nm. Narrow lines, not a spread.

Streetlights do not emit at those wavelengths, or emit only weakly there. So a filter that passes a 3nm-wide window around hydrogen alpha and blocks everything else removes something like 99% of the light pollution and almost none of your target.

This is why you will see people producing excellent nebula images from Bortle 8 city centres and it is not a trick. Under narrowband, a city sky and a rural sky are much closer than they have any right to be.

The catch: it only works on objects that emit in lines. Galaxies and star clusters shine across the whole spectrum, in the same broadband light the streetlights produce, and no filter can separate them. Narrowband helps nebulae. It does nothing for galaxies.

That single distinction organises the whole target list.

What works, by sky

Bortle 8–9 (city). Globular clusters, open clusters, double stars, the Moon, planets, and the Sun with proper filtration. All of these are bright enough that the background barely registers. With a dual-band filter, the big emission nebulae: Orion, the Lagoon, the North America, the Rosette, the Heart and Soul. Galaxies are essentially off the table apart from M31 and M42’s neighbours, and even those will fight you.

Planetary and lunar work is genuinely unaffected. A Bortle 9 image of Jupiter is indistinguishable from a Bortle 2 one. So is solar imaging, which happens in daylight and does not care about your sky at all. If you live in a city, these are the branches of the hobby that cost you nothing.

Bortle 6–7 (suburb). Everything above, more comfortably. Add the brighter galaxies — M31, M33 with effort, M81 and M82, the Leo Triplet on a good night. Add reflection nebulae in small doses. Emission nebulae without a filter become possible for the bright ones, though a filter still roughly triples your effective speed.

This is where most people are, and it is a perfectly reasonable place to do astrophotography. The limiting factor is patience: a target that takes four hours in Bortle 4 might take twelve here.

Bortle 4–5 (rural fringe). Faint galaxies come within reach. Integrated flux nebulae and the very faint dust structures start to be possible with long integration. Broadband imaging becomes genuinely pleasant rather than a fight.

Bortle 1–3. Everything, and the constraint becomes your mount and your patience rather than your sky.

The moon matters more than you think

A full moon in a Bortle 4 sky is worse than no moon in a Bortle 7 sky. People plan around light pollution, which they cannot change, and forget to plan around the moon, which is entirely predictable.

Roughly: the week around new moon is broadband time. The week around full moon is narrowband, lunar and planetary time. The weeks between are for targets high overhead and far from the moon in the sky.

If you have limited clear nights, matching target to moon phase is the highest-value planning you can do, and it costs nothing but a look at a calendar.

Altitude beats almost everything

A target at 30° above the horizon is being seen through twice as much atmosphere as one at 90°, and near a town that atmosphere is full of scattered light. The same object at 70° will be dramatically cleaner.

Shoot things when they are high. A target that is only ever 25° up from your latitude is a bad target for you regardless of your Bortle number, and that is a more common limiting factor than people expect.

What processing can fix, and what it cannot

Light pollution shows up in the stack as a gradient — one corner brighter than the other, or a dome of brightness rising from the horizon side of the frame. Gradients are removable. A model of the background is fitted and subtracted, and this genuinely works, to the point where the gradient is rarely the thing that limits a suburban image. There is a fuller treatment in removing light pollution gradients.

What cannot be removed is the noise the light pollution brought with it. Subtracting a bright background removes the brightness and leaves the grain. That grain is why a Bortle 7 image needs three times the integration of a Bortle 4 one to look equally smooth — and the only cure is more time.

Worth stating plainly, because a lot of suburban frustration comes from expecting background extraction to do something it fundamentally cannot.

A first-year target list for a suburban sky

Roughly in order of how forgiving they are:

The Moon. Any phase but full. Works from anywhere.
Jupiter and Saturn, when they are up and reasonably high.
M42, the Orion Nebula. Winter. Bright enough to be unfair.
M31, Andromeda. Autumn. Large — a short focal length helps more than a long one.
M13 or M22, globular clusters. Summer. Barely notice light pollution.
The Double Cluster. Autumn. Almost impossible to get wrong.
The North America Nebula. Summer, with a dual-band filter. Large and bright.
The Pleiades. Reflection nebulosity is genuinely hard from a bright sky — a good honest test of how far your setup goes.

Seasons above are northern. From the southern hemisphere, shift them by six months and add the targets the northern lists never mention: Eta Carinae, brighter and larger than Orion; Omega Centauri, the finest globular cluster in the sky by a distance; and the Large and Small Magellanic Clouds, which are entire satellite galaxies sitting high overhead. If you are south of the equator, start with those rather than working through a list written for somewhere else.

If number 8 works from your garden, your sky is better than you think.

The short version

Light pollution costs integration time, not targets, until the time gets absurd.
Narrowband filters make city nebula imaging genuinely viable. They do nothing for galaxies.
Planetary, lunar and solar work are unaffected by light pollution. Entirely.
Plan around moon phase and target altitude before you worry about your Bortle number.
Gradients come out in processing. The noise underneath them does not.

What Can You Actually Photograph From a Bortle 7 Sky?