"What lens should I get?" Aurora Lens Roundup

I have seen this question often on aurora-related forums. The whole reason to have an interchangeable lens camera is to use the best lens you can afford for the scene you are capturing, so what makes a good lens for capturing the aurora?

A good lens for aurora photography is...

"Wide and bright", specifically:

• f/2.8 or brighter. Ideally f/2.0 or brighter
• wide - 24mm or wider on full frame (which is 18mm or wider on APS-C) 
• easy to manually focus - autofocus is usually not used for night photography, so having some good manual focus control is helpful

Lens brightness matters

A brighter has a wider maximum aperture so can gather more light, but what does that actually look like? Here is a comparison of the different apertures for the same shutter speed:

Going from top to bottom, each row is 1 stop darker than the last row (half as much light), so you would need to double the exposure time to get the same brightness of picture. You can get the same brightness of image by just exposing for longer, but you may lose a lot of the fine structure in the aurora. For example a photo using the f/3.5 lens would have to have 3.5x longer exposure to have the same brightness as the f/1.4 (i.e. 10 seconds to 35 seconds)

Focal length

A wide lens will get more sky and aurora into frame. It is easiest to see with a comparison of focal lengths:

A wider lens can also seem more dramatic since the view arches above and below the viewer, giving a sense of presence in the scene. However if the aurora are on the horizon, a wider lens might just be capturing a lot of empty sky. 

Can't I just use my existing lens?

Probably! See this article about using a kit lens and camera for aurora.

But for a typical kit lens, your exposure time will have to be comparatively longer or your ISO (image sensor gain) will have to be set higher to get the same image brightness. This can result in a more smeared aurora or noisy aurora image.

About this list

This list focuses on the widest and brightest lenses for common lens mounts so you can get the best aurora images for your time and investment.

• This list is for Canon, Nikon, Fuji, and Sony mounts
• It doesn't include fish-eye lenses, just "rectilinear" ones that capture the scene as a viewer might see it
• Lens mount adapters are not included here, just lens mount availability. For example, both Canon and Nikon lenses can be adapted to Sony bodies
• For Canon EF, Nikon F, and Sony E-mount lens mounts, the full frame lenses can also be mounted on the cropped bodies offered by that company with about a 1.5x - 1.6x crop factor. i.e. a Canon EF-14mm can be mounted on a Canon Rebel, with a change in effective focal length of 14mm x 1.6 = 22mm

Image version below. PDF at this link