Create a portrait of the summer Milky Way

Using a wide lens, DSLR or bridge camera, a tracking mount and a little processing

Step 1

To fully capture the incredible granular Milky Way star fields, it’s crucial to devote time to getting the focus spot on. If you’re using a live preview screen for focusing, don’t use stars around the periphery of the frame to focus on, as often with wide-angle lenses optical aberrations make it harder to perceive the exact focus point.

Step 2

If you haven’t already done so, plan your composition in planetarium software (eg Stellarium). Now set your camera to a very high ISO and use short exposures to capture some test shots. For this kind of image it’s best not to include any earthly foreground, unless you are happy with it being blurred when we stack frames later.

Step 3

Change the ISO and exposure length to the settings you need to capture your sub-frames. These will be the level at which there’s a good balance between the amount of detail you’re getting in the star fields and the ‘fogging’ effect of any light pollution at your site. There’s no one-sizefits all, so experimentation is key.

Step 4

With a suitable exposure length and ISO selected, capture at least 10–15 minutes’ worth of data in total when shooting your main data. More sub-frames to stack later will help you create a smoother final image, something that’s especially important if you’re shooting at a high-ISO setting on a static tripod.

Step 5

Once you’re back home, consider if you’ll need some ‘flat field’-style calibration frames with the lens you used (see opposite for more details). When you have your data loaded onto your computer, inspect each sub-frame carefully and set aside any that show signs of cloud passing through the shot, mount vibrations or wind blurring.

Step 6

You should now have a folder of image files that you’ve inspected that represent the best frames from your capture sequence. You can now add, or stack, these together in dedicated astronomical processing software, whether that be free programs like DeepSkyStacker or commercial options like Nebulosity or PixInsight.

Step 7

A good first step is to enhance the contrast and brightness of your stacked shot via a gentle Levels or Curves ‘stretch’. Using the Curves tool in a program like Photoshop, adjust the diagonal line so that it takes on a subtle ‘s’ shape, bringing up the brighter elements of the image while increasing the contrast in the shadowier parts.

Step 8

If the post-processing software you’re using doesn’t have gradient or vignetting removal tools, you can do basic gradient removal using the technique outlined opposite. You may then want to return to step 7 to do another round of contrast and brightness enhancements (on the hopefully now-improved image) .

Step 9

Finish with basic colour balancing of your picture. Look for bright(ish) stars in your framing that have a neutral white spectral type (using software like Stellarium as a reference). Then use a colour balance tool in your processing software to adjust the picture’s overall colour so that the stars’ hue is as close to neutral white as possible.