How To Pick the Right Lens for Astrophotography

Posted by Nathan Horowitz on

What is astrophotography, exactly?

It’s a long word, but it’s just what it sounds like: the practice of photographing objects in space. If you’ve ever taken a photo of the full moon with your smartphone, you may have been disappointed at the image quality. The night sky is a vast, and many celestial bodies don’t photograph well.

The image quality depends on the type and quality of your camera and the lens. A simple point-and-shoot camera will produce very different images than the Hubble Space Telescope. Bring your camera gear into the 21st century and invest in a lens that will pick up the intricacies of a starry sky.

Choosing the right lens for astrophotography takes some research, but Samyang US is here to demystify the selection process. Use this guide as you shop to identify the features you’ll need to capture perfect celestial photographs.

Proper Focal Length

Many astrophotographers swear by wide-angle lenses when capturing images of the night sky. A wide angle means a large field of view, which is crucial for astrophotography. You want to capture as much of the night sky as possible.

A wide field of view (FOV) brings with it a shorter focal length. This attribute may seem counterintuitive if you want to capture crisp images of the stars.

Think about it this way: telephoto lenses have a long focal length and a narrow field of view. You’ll be able to observe celestial bodies more crisply through a telephoto lens, but capturing a still image is more difficult. With a telephoto lens and a long focal length, the image will be blurry due to the rotation of the Earth and the micro-movements of your own hands.

A short focal length allows you to capture wide expanses with minimal shake and blur. Samyang lenses are built for high optical quality, and place less emphasis on image’s stabilization and autofocus. You won’t need autofocus with a wide angle and a short focal length.

When shopping for wide-angle lenses for astrophotography, look for one under 35mm to capture the widest expanse possible.

Wide Aperture

The aperture of a lens is the opening that allows light into the body of the camera. To photograph the night sky, you’ll want the largest aperture possible to capture every speck of light. Ideally, your aperture should be f/2.8 or wider.

Using a wide aperture, however, comes with a few drawbacks. An f/4 aperture is extremely wide and can let in plenty of light, but the photo quality will dip and be blurry around the corners. If your astrophotography also incorporates the landscape around you, the objects on Earth won’t be as sharp as the stars.

The Rule of 500

Our Samyang lens kit comes in a variety of sizes, compatible with all major camera brands. If you know the dimensions of your camera, you can purchase a kit accordingly. To determine your shutter speed and maximum exposure time for the best photos, you’ll need to do some math based on the type of camera and lens you’ve got.

The 500 rule works best when your camera is mounted on a tripod for extra stability. Divide 500 by your equivalent focal length to determine the length of your shutter speed. For example, if you’re working with a 20mm lens, you’ll divide 500 by 20 to get 25 seconds.

It’s a good rule of thumb for estimations, though some photographers use the rule of 400 or 300. Try the rule of 300 if you intend to shoot stars along the celestial equator, as they move more quickly across the sky.

High ISO

The acronym ISO stands for the International Organization for Standardization, and the ISO value on a camera simply refers to the amount of light it allows into the lens.

For low-light shooting like astrophotography, you’ll want a higher ISO value (or speed) to collect as much dim light as possible. Manual-focus cameras will allow you to adjust this setting precisely based on how much light you need.

Astrophotographers often use an ISO value of around 1600. While that speed may not work in a well-lit room for taking portraits, it’s perfect for capturing bright stars in a dark sky.


We’ve mentioned it before, but it bears repeating: Samyang manufactures lenses for premier optical quality. We offer many lens kits that prioritize image quality over newfangled features like in-body stabilization and autofocus.

Manual focus lenses will give you more control over the image. When photographing the night sky, you don’t need automatic focus or stabilization; those features can actually hinder the quality of your images. In-lens stabilizing features don’t do much when shooting such faraway objects with long exposure times.

The best astrophotography lenses won’t do all the work for you; they’ll let you take the reins and manually adjust settings. You can make any size camera work for astrophotography with the right lenses, a tripod, and custom adjustments as you shoot.

Shopping for a Lens

When you browse Samyang’s wide selection of camera lenses, you may already know what all the numbers mean, but here’s a refresher:

Let’s say you’re looking at a 14mm f/2.8 model for your camera. The first number refers to the focal length; 14mm is a short focal length associated with ultra-wide angle lenses. The second number is the f-stop, or the maximum aperture opening. The smaller the number, the wider the aperture. 2.8 is remarkably wide, while 22 is extremely small.

Remember: for astrophotography, you’ll want a wide-angle lens with a short focal length (the first number) and a wide aperture (the second number). Samyang has spent years engineering high-quality, precise lenses that work with camera mounts from all the major brands. When you know the dimensions and needs of your camera, as well as the unique challenges of astrophotography, you’ll be able to find the perfect lens kit for you.

Astrophotography is a fascinating hobby and a unique way to expand your talents. Celestial bodies are highly different subjects than a family seated for a portrait. Choose your lens accordingly! To pick the right lens for astrophotography, get to know your camera, do a little math, and follow these helpful pointers as you shop.

How To Pick the Right Lens for Astrophotography

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