Who hasn’t dreamed about seeing other planets of our solar system or even anebula? Now more than ever, we can observe and capture them. In this article we will explore this job and passion, especially about planetary astrophotography. Beginning with what can you capture? What to do when you’re out shooting? And finally, what you can do after you captured your planets?
To get good pictures, a good preparation is needed; first you need to know what you want to shoot: the entire milky way, a time-lapse, planets, the Moon, nebulae or even galaxies.
Each one needs a different preparation and an optimal equipment. For a time-lapse or a milky way shot, a simple camera or wide view camera is recommended. A tracking mount is possible to get more light and details without trailing stars.
For planets, a telescope is recommended, the bigger the diameter, the better its capacity to brighten the image and have more details of the planet. More light also means more ease to distinguish dim objects like nebulae, galaxies, or the moons of other planets.
For planetary astrophotography, a tracking mount isn’t needed but makes it easier to have the planet dead center and keeping it there, especially with a telescope with a big focal (the focal is the distance that light travels inside the telescope) because the bigger is the focal, the more zoomed in the image will be, the planet will move fast in the ocular and you will need to readjust the telescope more frequently.
Once all this considered, the last preparation is to know when and where to go on your adventure, the best spots are, of course, spots where there isn’t light pollution and the highest ones. The best moment to shoot is when there is no clouds or wind, when the object you want to shoot is at the highest point in the sky, and when atmospheric perturbations are at a minimum, when you are in a high pressure area. To know where your planets will be when you’ll be capturing them, you can use sky maps or apps like Stellarium. Lastly, to shoot dim objects, watch out for the Moon phase and where it is, it kills contrast between the cosmic background and the object you want to capture.
Once on site
You are now at your spotting location, the first thing is to setup, if you have an azimuthal mount, make it level with a bubble. If you have an equatorial mount, make it level, and then align the right ascension axis with the rotation axis of the Earth. After, look for a bright star and focus your telescope, if you have a Bahtinov mask, make it like the central ray is in the center of the two others.
Once the setup is done, you can start your shooting session; in planetary astrophotography, the simplest way to have good results is to take many photos, or even take some videos. We’ll stack all those images later to have a sharper image.
It’s at this step that the telescope or lens is crucial, if you have a big aperture, a single image will be sharper and have more details. If you have a bigger focal, the image will be more zoomed in on the planet. Be warned to not zoom over the limit of your telescope or your lens, or the picture will be blurred. The maximum magnification can be calculated by multiplying aperture in millimeter by 2, and for a telescope, the magnification is calculated by dividing the focal of the telescope by the focal of the eyepiece, both in millimeter.
Once back home
Go to sleep! You’ve earned it, after a night outside, you’ll be better tomorrow to work on your images.
From here, many paths are open to you, you can keep what you have or stack your images with specialized software to have sharper pictures and more details. An astrophotography stacking software will take your best pictures and average all images to lower the noise of each image to later make it sharper.
The more you work on your pictures the better they will be, especially with galaxies and nebulas if you have those in addition with planetary shots. Apps like Photoshop will do.
Astrophotography is a passion and a job that can be complex and frightening for a beginner going in blind, however by taking time in learning all the basics, optics physics, mechanics… the observation and then capturing of celestial bodies will be easier, the observation being simpler and needing relatively less knowledge, is a great beginning for anyone moving his or her first steps in astronomy.