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The stars may look still, but Earth’s rotation can turn them into trails during a long exposure. The goal is to let in enough light to reveal faint stars without turning them into trails. That means your lens, sensor, aperture, shutter speed, and ISO all need to work together.

Key Takeaways

• Start with RAW, manual mode, the widest practical aperture, and manual focus set using a bright star rather than simply turning the focus ring to its infinity mark.
• For an untracked camera, calculate shutter speed with the 500 Rule as a starting point, but use a shorter exposure if your camera has a high-resolution sensor or you see star trails.
• ISO 1600 to 3200 is a useful starting range for Milky Way photography, but the correct value depends on your camera, sky brightness, and aperture.
• Stacking several shorter exposures can reduce random noise without forcing you to use a dangerously long shutter speed.
• Focus, light pollution, and shutter duration often have a greater practical impact on star detail than simply increasing ISO.

Start With RAW and Manual Mode

For night-sky photography, use Manual mode and RAW for full control and easier editing. Focus manually on a bright star using Live View, then lock the focus. With the camera on a tripod, turn off image stabilization to prevent unwanted movement. These basics give you a solid starting point for astrophotography camera settings, especially for Milky Way and wide-field shots.

Choose the Right Aperture

When choosing DSLR settings for astrophotography, aperture is one of the first settings to adjust because it controls how much starlight reaches the sensor. Yet sometimes there could be problems like coma or soft corners at the lens’s maximum aperture. In this case, you should use a smaller aperture by one stop.

Since this lets in less light, you may need to adjust the ISO or exposure time. The goal is not simply a brighter frame, but sharp, clean stars across the image. When planning your composition, royalty free sky images can also provide useful visual references.

Set Shutter Speed Before Raising ISO

Stars move across the frame as Earth rotates, so a shutter speed that is too long can turn sharp stars into trails.

As a quick starting point, use: 500 ÷ focal length = maximum shutter speed

For example, 20mm gives about 25 seconds, while 24mm gives about 21 seconds on a full-frame camera. On crop-sensor cameras, include the crop factor. Consider it more as a general rule than an exact guideline. If you see your stars becoming elongated, reduce your exposure time while increasing your ISO.

Pick ISO Based on the Whole Exposure

ISO does not really increase the amount of light in the picture. It amplifies the signal coming from the sensor, which may also amplify noise. When shooting the Milky Way, use an ISO between 1600 and 3200. This is a reasonable starting point, depending on your camera and how dark the sky is.

First, set the aperture and shutter speed; then set the ISO according to your desired exposure. If nearby light pollution is washing out the foreground, reduce the ISO or shorten the exposure time.

Focus on a Star, Not the Infinity Symbol

Autofocusing will often have problems in low-light conditions. Use manual focus, switch to Live View mode, enlarge the view of a bright star, then adjust the focus until the star looks like a tiny, sharp point. Do not trust the infinity mark on the ring because it is likely not accurate enough. Try not to touch the ring once the focusing is done.

Use White Balance for Natural Night Colors

When shooting in RAW, you can adjust the white balance, but you may start at 3,500K to 4,000K to achieve a realistic sky. Avoid pushing the white balance too far toward blue just to make the sky look more dramatic.

Match Settings to Your Subject

The best astrophotography settings change depending on the subject captured within the frame. If the scene consists of a Milky Way panorama, using a wide-angle lens, a wide aperture, ISO 1600-3200, and a relatively fast shutter speed can be a good start. If you are shooting during twilight rather than full darkness, the exposure changes significantly. Blue hour sky photos can use much lower ISO and smaller apertures because there is still substantial ambient light in the sky.

For star trails, take a series of exposures and stack them instead of trying to keep stars stationary. Moon photography also requires a separate approach because the Moon is much brighter than the surrounding sky.

Stack Frames for Cleaner Results

If you cannot capture sufficient data in a single frame without streaking, it is better to stack the frames. You will simply need to take multiple images of the same subject and then stack them using software. This process will average out the noise while retaining the stars. This technique is particularly useful when you want a detailed night sky picture while keeping stars sharp on a stationary tripod.

When the Settings Finally Click

There’s no single formula that works for every night. Start with a wide aperture and a shutter speed that keeps the stars sharp. Then adjust the ISO until you get a clean, well-balanced exposure.