For a couple of years now, the web has experienced a surge of attractive night sky images. The shots are so vibrant such that makes it inadequate to look at them once. While most people are used to the city life where there is no view of the Milky Way, the photos bring a picture of the world less seen by many.
Astrophotography involves capturing astronomical or space objects. Most photographers use a basic telescope as they start where they capture and share whatever they find fascinating. Others have come across the beautiful shots somewhere, maybe in magazines or on the internet, and wish to take their own.
Photographers will use the night sky to come up with pictures with close-up images of distant galaxies.
How does one shoot the night sky?
There is a long exposure that involves using the right equipment to shoot star trails or objects that are very dim. However, the use of modern digital SLR cameras has made it possible to use short exposure photography.
The cameras have outstanding low light capacities. Long exposure photography can be a bit complex when capturing objects such as distant galaxies. You need to have a lens with the correct focal length. The standard lenses used in photography will capture the moon quite well. However, to shoot deep-sky objects, you will need a large telescope.
There are different ranges of telescopes you will find. There are basic models and, even more, advanced with computerized mechanisms. Though it’s possible to attach the telescope and the camera, getting deep sky images is that easy.
To become excellent in astrophotography and come up with great images, you will need to give your time and practice a lot. Therefore, if you don’t get it right in the first trials, don’t be upset. It’s important to note that there is no perfect setting that will give similar results consistently. The reason behind this is the atmospheric light present in the area.
Gear and Equipment required for astrophotography
You will need a camera that allows you to do manual control on the shutter speed, the ISO, and the aperture. A DSLR camera is ideal equipment for that. Cameras with automatic control will not yield the results you want. Temperature control is the main compromise in the use of DSLR camera as an alternative to the astronomical cameras.
Cooling of the camera is crucial in reducing noise. Dedicated Astro-cameras come with the feature. Besides, they are sensitive to the red-light at the hydrogen-alpha wavelength. Light at that measurement is ideal for shooting the galaxies.
While the DSLR has a sensitivity similar to most Astro-cameras, there is a filter block to cater for day time photography. Therefore, DSLR cameras are not at par with astronomical cameras, which are built specifically for astrophotography.
You will need a tripod for support of your equipment. Remember, you will be shooting for long, and you have to stay still for the time. Choose a sturdy tripod to ensure the camera does not shake since that will result in blurred images.
While a remote trigger is not very crucial, it’s vital to you have it in your bag. The purpose is to prevent the camera from shaking on pushing the release button. However, if you can use a timer-setting to have the photos captured after a 2 seconds delay, in such a workaround, you will be away from the camera during the capture.
A remote trigger is another option that you can use to let the camera capture exposures of more than 30 seconds.
Which lens is the best for night sky photography? The most suitable is the one with a large aperture. An ‘f’ number, which you can present on the lens, denotes the aperture. Consider the lowest the number can reach is you do change the settings of the aperture.
It’s all about controlling the amount of light that gets into the camera via the lens. Since you will be doing night shoots, the best lens is the one with a larger opening, meaning a lower ‘f’ number. The selection of the lens is a crucial step in astrophotography.
During long exposures, a flashlight is critical to help illuminate subjects in the foreground of your image. For instance, it is great when you want to portray a tree in your photo. Besides, you can use it when you want to appear in the image. It is through the trick that you find images with a person pointing on a distant object.
How to shoot astrophotography?
Below are the steps you will follow from the beginning until you get that image.
Find your location
To end up with great images, you need to find a place where you can view the night sky.
The location is very critical in astrophotography. The darkest places are the best. Put off all the lights around you and let your eyes acclimatize for some time. Therefore, you will be trying to be away from cities and towns. There is an illumination of the artificial light in such places.
When doing star photography, artificial light makes it difficult to see the stars. The best location is the international dark sky reserves since the light is either negligible or absent to bring interference to your photography.
Subjects are the points of interest that you would like to be part of your photos. They appear in the foreground of your image as the bright stars appear in the background.
You will now set the camera on the tripod. The legs should lock well and tightly to avoid any shaking of the camera.
Set the shutter speed
You will now set the shutter speed and the camera on manual mode. When doing astrophotography, you want the slow shutter speed to have long coverage duration. The camera will have enough time to capture the minute light flickers. The best length, to begin with, is 20-30 seconds.
It is important to note that since the earth is rotating, the stars make minor shifts in position in front of the camera. Therefore, the image will have star trails. Though the photos may look exceptional due to that, you can use rule 600 helps to avoid the trails. It involves dividing 6000 to the focal length you are using in capturing the images.
The value you get is the shutter speed you should use before the stars start forming trails on the photos. For instance, if your focal length is 20, then 600/20 =30. It means that 30 seconds is the shutter speed you should set to avoid star trails on your images. If you like the star trails, you will need to shoot in a series.
For example, you can take 50 images in succession; you will then create the star trails in post-processing.
Set the ISO and aperture
ISO is the sensitivity. You will need to set it together with the aperture accommodating the exposure duration. The first image will assist you in making the necessary adjustments.
What is the best aperture for astrophotography?
When it comes to setting the aperture, you will need to shoot with the smallest ‘f’ number. It will let in a vast amount of light into the camera. Therefore, you can capture images with a lower ISO. You can as well slow the shutter speed.
What is the best ISO setting for the night?
The ISO should be between 800-2000. Alternatively, you can try to reduce the shutter speed and maintain the ISO on the lower end of the gauge to reduce noise on your images.
Focus the lens
So, how do you focus a lens for astrophotography?
The safest mode of focusing when capturing distant objects is setting the lens on manual focus and adjusting it to infinity. The infinity is denoted by either ‘I’ or ‘L’ mark on your lens’s focusing ring. Other than the infinity, you can focus on a distant light or a bright point around 300m away.
When set, take an image and then zoom on the distant objects using the Liquid Crystal Display and magnification button on the rear of the camera. Make slight adjustments on the focus and take another photo if the current is not 100 percent sharp. You will repeat until the distant objects are in focus.
When focusing on a subject, you will need to set the camera to autofocus, paint the subject, and focus until the camera show that the focus is right. You will then switch back to the manual focus while the focusing ring remains still. At that point, all of your photos will be sharp and in focus.
Turn off the noise reduction
The two forms of noise familiar with most cameras are long exposure and high sensitivity (ISO). How do you reduce noise in astrophotography? You can set high ISO during post-processing since it does not affect the raw files. However, it may alter details from Jpeg photos.
The reduction of long exposure noise doubles the duration taken to capture each image. Additionally, it leads to erroneous removal of some objects. When used star-trail photos combined from numerous shots, it may cause breaks in the trails.
Use the self-timer or a remote release
To avoid blurred images, you will use a remote release. If it’s not available, a self-timer will be okay.
Some lenses come with stabilization control, though not all. If yours has it, you will need to deactivate it when capturing long term exposures with a tripod. Having the stabilization control off prevents the camera from attempting to stabilize any shake automatically. The tripod supports the camera for you, so you don’t need the mode is not necessary.
It is a stage where you refine your captured images. Once you shoot astrophotography, the photo needs some enhancements.
There is no need to be frustrated if the images you capture aren’t precisely similar to those you have come across on the web or magazines. There is a lot of refinement that happens in post-processing to enhance the photos. You can carry out adjustments on the whites, exposure, and highlights.
If you are for star trails, then this is your place. Hopefully, you now have the images of stars that you took in a series. You will need to import all of them into the lightroom where you will apply all the adjustments you need into one photo.
You will load them into photoshop and then highlight all of them together. Finally, change the layers tab from normal to lighten setting.
Remove satellite trails
There are developments about SpaceX’s intentions to launch Starlink satellite constellation. It is a move that raised concerns from astronomers, why? Well, the satellites are a threat to both radio and visual astronomy. Though satellite trails are not that damaging to your deep-sky photos, there are ways to remove them.
You will not need to use all your time in photoshop, removing them. The process works by averaging all the pixels in a photo and identifying which image deviates from the mean value in comparison. It could be because they are either too faint or bright compared to similar pixels in other frames.
The program eliminates all those photos whose pixel values are out of range. That way, the final image will not be affected. It is an easy way of removing satellites, UFOs, and planes from the last photo.
Color balance in astrophotography
Balancing the color in your photos is a fundamental technique you should apply in post-processing. It goes beyond the primary calibration of images, and you can do it regardless of the software you have.
Before you learn the technique, you need to grasp monochrome data. It will help you in calibration, stacking, and stretching a single color at a time. After that, you will move to balance the color between three channels.
You will enjoy astrophotography most away from the city. Therefore, it may require you to travel and do some planning if you dwell. You should be ready to spend a long evening in the wilderness to have a spectacular view of the night sky.