Dark skies
Better sky beats better gear by a margin most people find annoying. An hour of driving usually buys more image quality than a thousand dollars of equipment, and it keeps buying it on every future night.
The Bortle scale
John Bortle published this scale in 2001 to give observers a shared vocabulary. It is descriptive rather than instrumental, so the SQM and naked-eye limits below are the commonly quoted approximations rather than definitions.
Scale reference ↗The Milky Way casts a shadow. Zodiacal light is obvious and coloured, and airglow is visible near the horizon.
Shooting here: Broadband deep sky works without filters. Your limit becomes your tracking and your patience.
Summer Milky Way is highly structured. Zodiacal light can cast shadows at dusk.
Shooting here: Faint reflection nebulae and galaxy outskirts become realistic in a single night.
Some light pollution on the horizon. The Milky Way still shows real structure overhead.
Shooting here: The practical sweet spot for most nightscape work. Most people drive here, not to Bortle 1.
Light domes are clearly visible over towns. The Milky Way is obvious but loses fine contrast.
Shooting here: Milky Way photography works well. Broadband galaxies start needing careful gradient control.
The Milky Way is washed out near the horizon and only visible overhead on the best nights.
Shooting here: Dual-band and narrowband filters change everything here. Broadband targets get hard.
The sky glows greyish white in all directions. The Milky Way is essentially invisible.
Shooting here: Narrowband emission targets, the Moon and planets. Do not expect faint galaxy structure.
The entire sky is light grey. Only the brightest constellations survive.
Shooting here: Narrowband still delivers. Short subs and many of them, because the sky fills the histogram fast.
Bright enough to read a newspaper outdoors. The Pleiades looks like a smudge.
Shooting here: Moon, planets, bright doubles and hydrogen-alpha. Plenty of excellent work gets made here.
The Moon, the planets and a handful of stars. Nothing else.
Shooting here: Lunar and planetary imaging, solar with proper filters, and narrowband if you are stubborn.
Most people are chasing Bortle 3 or 4, not Bortle 1. The jump from a suburban 6 to a rural 4 transforms what you can photograph. The jump from 3 to 1 is real but much smaller, and it usually costs a very long drive.
Finding a site
The best dark site is the one you can reach on a weeknight and get home from safely. Perfect skies four hours away get used twice a year.
Light pollution overlays are built from satellite radiance data and they are far more honest than your instinct about where seems remote. Somewhere that feels dark because there are no streetlights can still sit inside a city's light dome. Check the actual colour on the map before you drive.
Light pollution atlas ↗A site 40 miles from a city with the city to the north is excellent for southern targets and useless for northern ones. Since the Milky Way core sits south for northern observers, a clean southern horizon is usually worth more than a marginally darker sky in every direction.
DarkSky International certifies parks, reserves, sanctuaries and communities that meet real lighting standards and commit to keeping them. There are now over 250 of them worldwide. They are not the only dark places, but they are the ones actively defending their darkness.
Dark Sky Place finder ↗Every serious problem with a dark site is invisible at night: a locked gate, a soft shoulder, a drainage ditch, private land, a hunting season, cell coverage that drops a mile before the turnoff. Go once in the afternoon and you will never have that conversation with yourself at 2am.
A sky quality meter reading gives you a number to compare sites with. Above about 21.5 magnitudes per square arcsecond, handheld meters get unreliable, so treat very dark readings as approximate. Photographs of the same target with the same settings are honestly a better long-term comparison.
Field ethics
Dark sites lose access because of behaviour, not because of photography. DarkSky International publishes principles for responsible astrophotography that are worth reading in full.
Read the principles ↗Full dark adaptation takes about twenty minutes and one white headlamp destroys it for everyone within sight. Use red, keep it dim, and point it at your feet.
Brake lights, reversing lights and interior domes are the most common complaint at any shared dark site. Learn where your car's light switches are, and use parking brake instead of holding the brake pedal.
Low-level landscape lighting is a legitimate technique. Doing it beside someone running a two-hour deep-sky sequence is not. Ten seconds of conversation solves it.
A specific arch, a specific tree, a specific hot spring. Naming the region is generous. Dropping exact coordinates is how quiet places stop being quiet.
Including the tripod holes in soft ground, the tape you used, and every battery you brought. Especially the batteries.
Night-adapted animals are far more disturbed by light and noise than daytime ones, and they were there first.
Once you have a site
Enter the coordinates of your site and the planner works out the darkness window, the moon, and everything above the horizon.