Shooting light at night - the Northern Lights

Comments

• bruto

  January 2017 edited January 2017

  It's going to be a challenge to get a clean picture, but the first thing you should probably do is determine for yourself what ISO you can go up to without too much noise. That may be a matter for judgment, but also depends on how big you print, and how much you post process. It will always be a bit of a compromise with a non professional DX format camera.
  
  Let us guess that the D5100 can go up to about ISO 800 without too much fuss. That may be a little grainy, but not likely bad. You might even be able to go higher, but don't count on it.
  
  It's nearly impossible to use auto focus at night, so you'll have to manually focus. Choose the furthest clear subject on the horizon that you can find. Do not just crank the lens to its infinity stop, because most modern zoom lenses will go past infinity, and focusing past will be blurrier than focusing short. Beyond a few hundred feet infinity will be enough in focus not to notice.
  
  You'll need a tripod for sure, and a wide angle. If you're using the kit zoom, put it at 18mm. The wider the better. You'll want to use a manual exposure, and turn off Auto ISO, or the camera's meter will intervene, and will likely overexpose a dark sky. Set the aperture as wide as it goes - you're not going to need any depth of field, since it's all up in the sky - and set your shutter speed to about 20 seconds for starters. More or less will become apparent after you've tried one.
  
  If your northern lights are pulsating or shaking or moving, compensate for any overexposure by shortening shutter speed rather than closing down the aperture, and if it's all looking good except for overexposure, lower the ISO. The shorter the shutter speed, the better, but not if it's either badly exposed or too noisy, so it's always going to be a compromise between ISO noise and shutter speed.
  
  To avoid any shake, you're probably best off using the self timer unless you have a remote shutter release.
  
  I don't know just what noise reduction is available on the D5100, but long exposure noise reduction should probably be turned off. If there's only one "noise reduction" item on the menu as there is for the D3200, turn it off. What this option does, aside from some JPG noise reduction, is to take a second exposure of the blank sensor and subtract the noise on that from the noise on the image. It does a small amount of good, but doubles long exposure times. That means a 20 second shot will take 40 seconds, and you cannot shoot continuously because it's actually using the sensor during that time.
  
  I haven't done Northern lights for a while, not since switching from film. Alas, there haven't been any for a while, but I got a few good ones in the past.
  
  You can look around the internet for further suggestions. Auto modes will probably do badly, and all cameras in manual mode will behave about the same, so the settings are likely to be pretty universal.