Focal length is one of the most important things you must consider before buying a lens for astrophotography. Astrophotography is rewarding yet very technical and complex. Whether you want to photograph the stars, galaxies, or moon, getting the right focal length is vital, especially if you want to achieve high-quality results. The right focal length will allow you to capture more detail and help ensure that your images are sharp and clear.
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Before diving into the best focal length for astrophotography, it is essential to understand what focal length is and its effects on photos. Focal length is the distance between your lens and the film plane or sensor when you focus the lens at infinity. It will determine your images’ field of view, magnification, and perspective.
The best focal length for astrophotography directly depends on the object you want to capture. If you are just getting started in the niche and want to capture the plain beauty of the night sky, then we recommend a wide-angle lens with a focal length between 14mm and 35mm. These lenses will give you a wider field of view, which is perfect for capturing the expansive night sky. They will allow you to click sharp and well-defined images of the Milky Way, constellations, auroras (if you are in the right location), and other objects in the sky.
However, wide-angle lenses can distort your images. If you are not careful with composition, they might not give you the magnification needed to capture close-up shots of the moon or planets.
We recommend the following wide-angle lenses:
- AF-S NIKKOR 14-24mm f/2.8G ED
- Sigma 20mm f/1.4 DG HSM Art Lens.
- AF-S NIKKOR 20mm f/1.8G ED
- Rokinon (Samyang) 24mm f/1.4 US UMC Lens
- AF-S NIKKOR 24mm f/1.4G ED
Image shot at 14mm with AF-S NIKKOR 14-24mm f/2.8G ED.
On the other hand, a lens, such as a telephoto lens, with a longer focal length will give you more magnification and a narrower field of view. This is generally best if you intend to capture clear and detailed pictures of the moon and deep-sky objects like galaxies and nebulae. We suggest a 200mm or 300mm telephoto lens for this purpose. Although they are typically heavier, more expensive, and will demand you use a stable tripod to prevent camera shake, they will give you the required magnification to capture night sky details like the rings of Saturn.
Images shot with a telephoto lens.
Credit: Nikon
We recommend the following telephoto lenses:
- AF-S NIKKOR 70-200mm f/2.8G ED VR II
- Canon EF 300mm f/2.8L IS II USM Lens
- AF-S NIKKOR 70-200mm f/4G ED VR
Apart from the wide-angle and telephoto lenses, a normal or prime lens with a focal length of around 50mm to 58mm is another great choice for astrophotography. Such lenses are usually versatile, making them ideal for capturing the Milky Way and star trails. They are also lightweight and easier to carry.
Captured with a 58mm f/1.4G lens.
Credit: Nikon.
We recommend the following prime lenses:
- AF-S NIKKOR 58mm f/1.4G
- Sigma 50mm f/1.4 DG
- AF-S NIKKOR 50mm f/1.8G
- Canon EF 50mm f/1.8 STM
Before you choose a lens for astrophotography, ensure you consider the:
- Aperture – we recommend lenses with a maximum aperture of f/2.8 or wider.
- Image stabilization – look for a lens with in-body image stabilization.
- Weight – you might find it difficult to carry or hold a heavy lens for a longer period. So go for something light.
- Price – always work within your budget.
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What Focal Length Is Best For Milky Way Photos?
Generally, a wide-angle lens with a focal length between 14mm to 24mm is best for capturing the Milky Way. A wide-angle lens will allow you to capture a large portion of the night sky, giving you a great chance to include the Milky Way in the shot. It will also help you to photograph more stars and foreground details.
However, whether to use a wide-angle or prime lens for the Milky Way will depend on your camera’s sensor size, your desired depth of field, and the type of images you want to great. Regardless, wide-angle lenses (with a focal length between 14mm to 24mm) are the most commonly used among astrophotographers for Milky Way photography.
In conclusion, the best focal length for astrophotography will depend on the celestial objects you want to capture. We suggest a wide-angle lens with a focal length between 14mm and 35mm if you want to capture the beauty of the night sky. A telephoto lens will allow you to capture deep sky objects, while prime lenses are versatile, making them ideal for capturing star trails.