Ian Evenden

The advantages of shooting in RAW

Our original, unedited picture of the Northern Lights as seen in southern Canada. The shot was taken with a camera set to capture images as Jpeg files

After passing the RAW file through Adobe Lightroom and adjusting highlights, shadows and saturation, the image has considerably more definition and punch

All DSLR cameras and many premium compacts are able to capture images as RAW files instead of the more common Jpeg. You’ll find the option in your camera’s image quality settings, and some cameras can capture an image as both types of file at once.

A good way to look at RAW files is as a simple dump of the camera sensor’s data at the moment of exposure. They offload all image processing to your computer rather than using the camera, giving you complete control over the process. They’re larger than even the finest Jpeg, as they’re completely uncompressed and contain more information than images in the more common format.

To read a RAW file, you’ll need an image editing program. Adobe, as ever, is the king of RAW decoding, with its Lightroom workflow software making the importing, organising, editing and exporting of files a fast and relatively pain-free affair. It’s available as part of Creative Cloud subscription packages or as a standalone purchase, but the cheaper Photoshop Elements, Affinity Photo (Mac only) or freeware GIMP (you may need a plug-in) will do the job too. If your camera came bundled with software from the manufacturer this can be a great choice too, as the software will be perfectly tuned to your chosen brand.

So far, shooting RAW files may sound like more trouble than it’s worth. Larger files take up more space and the need to buy software can put people off. But there are advantages for astrophotography – one of the biggest being that you have more data to work with.

A richer palette

Jpeg compression creates smaller files but throws away image information in the process, which is known as ‘lossy compression’. You also lose information from a Jpeg due to it being an 8-bit file.