Introduction
When it comes to capturing the beauty of the night sky through photography, it can be quite challenging. Without optimal camera settings, you may end up with dark photos, motion blur, or unsharp corners. This becomes even more difficult if you want to include a sharp foreground or capture deep-sky images of distant interstellar objects. Fear not, as this article aims to provide you with a comprehensive guide on setting up your camera properly for astrophotography.
Before diving into specific recommendations, it’s important to note that the techniques discussed here are ideal for capturing sharp stars from a landscape photography perspective, where stars are not the sole focus of the photo. For astrophotography with a telescope or capturing star trails in a landscape photo, more specialized information may be required beyond the camera settings mentioned below.
Focal Length
When it comes to nighttime photography, the choice of focal length plays a significant role in the type of image you wish to capture. While you can shoot nighttime photos at any focal length, the decision depends on the desired outcome.
If your goal is to photograph a classic landscape with the Milky Way overhead, and you want everything to be as sharp as possible, using the widest possible lens is the best approach. Ultra-wide lenses offer several advantages for capturing the night sky. Firstly, they allow you to include more of the Milky Way in your images due to their wide field of view. Secondly, wide lenses have greater depth of field, making it easier to achieve a sharp foreground. Lastly, these lenses enable longer exposures before star movement starts to blur the image, thereby allowing you to capture more light.
Personally, a preferred focal length for this type of photography is anything 20mm and wider, although longer lenses can also be used. If you don’t mind blurry stars or intentionally want to capture that effect, a longer focal length may be more suitable. For instance, capturing motion in the stars can be achieved by using a longer focal length, coupled with an extended exposure. Deep-sky astrophotography, on the other hand, requires a long lens to capture distant objects in the sky.
Takeaway:
- Use a wide-angle lens to capture as much of the sky as possible, increase depth of field, and employ longer shutter speeds.
- If capturing motion blur in the stars or using an equatorial mount, choose the focal length that best suits your composition requirements.
Aperture
Aperture, one of the most crucial settings in photography, takes on a slightly different role in astrophotography. In this context, using the widest aperture on your lens, or near it, is generally recommended.
Stars emit such dim light that capturing them as brightly as possible requires utilizing all available means. Ideally, an aperture of f/2.8 or wider is preferred, although lenses with a maximum aperture of f/4 can also work to a certain extent.
However, shooting at the widest aperture does present a few challenges. Image quality, especially in the corners, may suffer, particularly if you include a foreground in your composition. Additionally, the narrower depth of field that comes with wider apertures may not be ideal for some situations.
If your lens has a maximum aperture of f/1.4 or f/1.8, it is worth testing its performance at these wider apertures. Pay attention to issues such as vignetting and coma (smeared stars in the corners). If these problems are particularly severe, it may be prudent to use an aperture that is slightly smaller, perhaps 1/3 to 2/3 stop smaller. However, if your lens has a maximum aperture of f/2.8 or f/4, it is generally not recommended to stop down further, as light may already be limited.
The decision regarding aperture settings involves finding a balance between capturing sharper corners and gathering sufficient light. There is no definitive answer as it largely depends on your lens and personal preferences. If unsure, it is advisable to take photos at various aperture settings in the field to determine the optimal choice.
Personally, when using my main wide-angle lens with a maximum aperture of f/2.8, I typically shoot at that aperture for astrophotography. However, when using a Nikon 20mm f/1.8 lens to photograph the Milky Way, I may use anything from f/1.8 to f/2.2, depending on the tradeoffs I am prepared to make on a given day.
Takeaway:
- Shoot at the widest aperture setting possible, especially if your lens’s maximum aperture is in the range of f/2.8 to f/4.
- If your lens’s maximum aperture is in the range of f/1.4 to f/2, consider the level of coma and vignetting in your images. To prioritize slightly sharper corners over maximum light capture, use an aperture that is 1/3 to 2/3 stop smaller.
Shutter Speed
Shutter speed is one of the “big three” settings, alongside aperture and ISO, that significantly affect astrophotography. It plays a crucial role in determining the brightness of your nighttime photo and the amount of motion blur in the stars.
Stars move across the sky faster than one might imagine. While capturing multi-minute exposures of the Milky Way to gather as much light as possible would be ideal, practical limitations come into play if you want to capture sharp stars without using an equatorial mount.
The potential shutter speed before capturing motion blur depends on several factors. Firstly, as mentioned earlier, the focal length influences the length of the shutter speed. Wider lenses allow for longer exposures before star movement becomes noticeable. The direction you are facing and the rotation speed of stars around Celestial North and Celestial South (such as our North Star in the Northern Hemisphere) also have an impact.
An individual’s willingness to accept motion blur in their photos is another factor. Some photographers prefer no movement at all and limit their shutter speeds to around five or ten seconds for night shots. Others are more tolerant of star movement and may push shutter speeds to the range of 20-30 seconds for the same shot.
However, there is a point of diminishing returns. Once a star has completely moved from its original position, increasing the shutter speed further will not make it brighter (apart from creating the illusion of brightness due to increased size and blur). Many astrophotographers aim to capture dim stars, so it is crucial to note that an ultra-long shutter speed is not the answer unless you are using an equatorial mount. In fact, it may only amplify background light pollution, reducing the visibility of stars.
In general, the optimal shutter speed for most nighttime work falls within the range of 10-25 seconds, varying depending on the specific situation. Personally, when shooting with my 14-24mm f/2.8 lens, I tend to use a shutter speed of 20 or 25 seconds, but this ultimately depends on the desired image.
Takeaway:
- For capturing sharp stars, the shutter speed usually falls between 10 and 25 seconds, depending on factors like focal length and composition.
- In-depth calculators can help determine the optimal shutter speed, but trial and error in the field is often a quicker approach.
ISO
Determining the perfect ISO for astrophotography, just like in other types of photography, can be a complex task. In the context of capturing the Milky Way, two schools of thought prevail.
Firstly, one can shoot at an ISO value that produces photos with the desired level of brightness, typically ranging from 1600 to 6400 due to the dark nature of nighttime scenes. Secondly, choosing an ISO value that prevents as many stars as possible from “blowing out” or overexposing is also a valid approach, usually falling within the range of 100 to 400.
For most photographers, shooting at a high ISO value is recommended for nighttime photography. However, it may sound counterintuitive, but in some cases, capturing Milky Way photos at the camera’s base ISO (resulting in a very dark image) and later brightening it in post-production can be a viable technique.
It’s worth mentioning that the explanation which follows is more technical and may not be relevant for all photographers. Some cameras exhibit ISO invariance at low ISOs, meaning that there is no discernible difference between brightening an image in-camera using a higher ISO setting versus adjusting brightness in post-processing software like Lightroom or Photoshop. The concept behind this is that higher in-camera ISOs may introduce loss of detail in stars, so shooting at a lower ISO and enhancing brightness later in post-production becomes a viable alternative. It is important to note that not all cameras exhibit extreme ISO invariance, and some are only close to it.
Particularly, my Nikon D800e camera is close to ISO invariant within a certain ISO range, which leads me to occasionally employ this technique. However, it’s not completely invariant at lower ISOs, so I typically stick to shooting at higher ISO values, such as ISO 1600 (the highest “real” ISO on my camera).
Unless you are well-versed in the intricate details of your camera’s sensor response and desire that extra level of detail in stars, it is recommended to simply shoot at a high ISO value that results in bright nighttime photos, typically within the range of ISO 1600 to 6400.
Takeaway:
- For most photographers, shooting at a high ISO value that delivers bright nighttime photos, usually ranging from ISO 1600 to 6400, is sufficient.
- If you know that your camera sensor is ISO invariant within a certain range, shooting at the lowest ISO that is invariant (the highest “real” ISO) and adjusting brightness in post-production can be beneficial.
Other Settings
While aperture, shutter speed, and ISO are the most significant camera settings for astrophotography, there are other considerations worth mentioning. The foremost is shooting in RAW format instead of JPEG to maximize image quality, especially in challenging nighttime conditions. If you haven’t already made the switch to shooting in RAW, it is highly recommended, and our RAW vs. JPEG article provides further insights.
It’s important to note that many camera settings affect RAW photos differently than JPEGs. These settings are not baked into the RAW file, so they do not impact ultimate image quality. Examples include high ISO noise reduction, white balance, and Picture Control/Style. Therefore, assuming you are shooting in RAW, there are fewer details to worry about in the field.
However, certain behind-the-scenes settings still affect RAW images, including one that is particularly relevant for astrophotography: long exposure noise reduction. This setting involves taking two sequential photos: the first captures the scene, while the second is a “dark frame” with no subject. The dark frame contains noise and hot pixels similar to those in the first photo. The camera subtracts the dark frame from the initial image, resulting in a cleaner photo.
Long exposure noise reduction does impact RAW images and, therefore, is an essential setting to consider. However, it brings its own set of considerations, as it doubles the time spent capturing each image. While this may not seem significant initially, it can become cumbersome over time. Some photographers opt to capture their own dark frames and subtract them during post-processing, while others choose to leave the setting turned off altogether. Regardless of your decision, it’s important to be aware that long exposure noise reduction is available and can be a valuable option.
And with that, we have covered the most important camera settings for astrophotography. If you have properly focused the image and are shooting in RAW format, there are primarily three aspects to focus on: aperture, shutter speed, and ISO. It’s crucial to find a balance among these settings to capture stunning night sky images. Now, all that remains is to find the perfect composition and let your creativity shine.
Takeaway:
- Shoot in RAW format for superior image quality in astrophotography.
- Long exposure noise reduction can significantly reduce noise and hot pixels but doubles the image capture time.
Conclusion
Nighttime photography, particularly astrophotography, is a complex endeavor, with countless possibilities and intricacies (just ask the Hubble Telescope!). Nonetheless, armed with the recommended settings mentioned above, you now have a solid starting point for your own astrophotography endeavors. It is important to remember that settings may vary depending on the specific shot you aspire to capture, be it a wide-angle landscape or a deep-sky image. Ultimately, the chief aim is always to capture the magic of light dancing across the night sky.
Takeaway:
- Experiment and explore the world of nighttime photography.
- If you have any questions or tips regarding astrophotography, feel free to leave a comment below.
The article is compiled and compiled by tipcamera.com
