Shooting the stars

The basics

Lately we have been taking photos at night homing in on stunning night sky shots of meteors, the Milky Way and star trails. Setting the camera to manual control, a fast wide lens, RAW capabilities and a big sensor makes all the difference. It is not easy to shoot stars and you need to decide on where you want to go. So far, we have focused on shots where the stars appear as stationary specks or points of light. However, very soon we need to start taking photos where the stars appear as streaks due to the Earth’s rotation. To capture meteors or steady stars in the Milky Way, exposing for points of light is generally best because it allows the shooting stars to track across the frame – an effect that requires the camera to remain totally still and the exposure time relatively short.

The darker the better

Getting away from city lights will increase the chances of getting that crisp belt of stars decorating a black carpet. We use heavy tripods with a locking ball head to keep the camera as still as possible during the exposure. Remember the Earth’s rotation matters; even a 10 second exposure will leave the stars as small streaks. You also want to avoid any form of shakes; I use a remote to limit any manual movement of the camera. Not long ago we went out aiming to catching meteors, but it proved more difficult than expected. The lesson learned from this was that it is best to shoot continuously during a meteor shower, while a combination of a high rate of fire increases your chance of capturing a shooting star, or several. The Sony Alfa A99V offers continuous capture, shooting one photo while processing the previous shot to eliminate noise.

Figure 1 Photo of Sletterhage Lighthouse shot by Claus Møller

To avoid streaks, we keep the “500 rule” in mind. It is a rough tool for figuring out how to avoid noticeable blur, or unwanted star trails. Take the number 500 (multiplied by the crop factor if you are not on full frame) and divide it by the focal length of your lens to get maximum time in seconds before trails will appear. The number 500 is only a rough guide, and new optimized sensors affect it, so experiment with it until you find your camera’s number. The correct number is typically somewhere between 450 and 600.

Open the aperture as wide as possible (If the stars are the only consideration in your subject). We usually work with ISO within the range of 800-6400. Using a higher ISO setting will introduce too much grain into the image. From there it is about fine-tuning based on what looks good, the amount of ambient city light affecting the shot.

Milky Way shooting

One of the good things about stars is they always have the same brightness, so any adjustments you need to make will have to-do with either light pollution or moonlight. As we are particularly interested in getting as much light through our lens, you need to pick the widest aperture (lowest f-stop) your lens offers.

The only reason to choose a higher f-stop and reduce the aperture is if your lens is giving blurred edges due to optical aberrations.

Standard Milky Way exposures

  • f/1.4    ISO 1600    30sec
  • f/2.0    ISO 3200    30sec
  • f/2.8    ISO 6400    30sec
  • f/3.5    ISO 10000    30sec
  • f/4.0    ISO 12800    30sec

Helpful trick when setting focus.

Focus manually; the focus point is going to be close to infinity, but not quite. The “Focus magnification” is a very helpful tool here (Sony Alpha A99V Page 103). Once you have set your focus, secure your lens with a piece of good-quality insulating tape or duct tape.

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