ZOOM TO THE STARS

Here’s a fab four of wide-angle zooms for astrophotography, ideal for capturing the night sky in all its glory

Wide-angle zooms are favoured for landscapes, as well as for architectural photography. But turn your gaze heavenwards on a star-studded night and you can take in a whole new perspective. For shooting the Milky Way with a full-frame camera, a zoom range of around 15-24mm fits the bill.

You’ll need to suck in as much light as possible, so a fast aperture of f/2.8 is ideal. This avoids the need to send your ISO setting into the stratosphere in order to keep exposures short enough to stop stars trailing across the sky.

So what makes a good zoom lens for astrophotography? As well as good sharpness across the whole frame, you’ll want to watch out for aberrations that degrade image quality at the widest available aperture. Towards the corners, these include vignetting, ‘coma’ – which gives celestial bodies the appearance of having a comet-like tail – and ‘astigmatism’, which turns dots of light into lines – and a combination of coma and astigmatism can produce an irregular shape sometimes referred to as ‘batwing coma’. Spherical aberration can also occur throughout the entire image frame, giving points of light a soft halo effect. Helpfully, all of these aberrations tend to be greatly reduced when you narrow the aperture by an f-stop from its widest setting.

Zoom lenses aren’t the only solutions for shooting stars: wide-angle primes are a viable alternative. You’ll lose the flexibility of being able to adjust the focal length, but you’ll sometimes get a faster aperture rating. Two of our favourite primes for astrophotography are the Irix 15mm f/2.4 Blackstone and the Samyang XP 14mm f/2.4. For now though, let’s get back to the zooms…