Beginner’s Guide to Deep-Sky Astrophotography
Have you ever wondered how everyday people use their DSLR camera to photograph deep-sky objects in space? If you have ever looked through a telescope, you probably already know that the vibrant colors and contrast you see in the images do not appear that way in the eyepiece. This is because cameras can record much more light that our eyes can.
If you are interested in taking your own photos of the astonishing deep-sky objects in the night sky such as the Orion Nebula and the Andromeda galaxy, this beginner astrophotography guide will get you on your way.
A Beginner’s Guide to Deep-Sky Astrophotography
All of the photos on this website were captured using a very basic DSLR astrophotography setup for deep-sky imaging. Below, you will find the items you will need as well as the basic process I use. For a complete list of the equipment I am currently using, please visit the “my equipment” page.
There are a few types of astrophotography cameras used to take pictures of objects in space including the sun, planets, galaxies, nebulae, star clusters, comets and more. The type of astrophotography you will find on my site is known as Deep-Sky DSLR Astrophotography. This means that I use a DSLR camera and a telescope to capture an up-close view of objects such as galaxies and nebulae in space.
It is important to first understand the characteristics of your DSLR camera, before advancing your skills towards capturing deep-sky objects including galaxies and nebulae. Deep-sky astrophotography involves learning the basics of camera operation, telescope control, and image processing. All three of these elements come together to produce stunning images of our night sky.
Basic Beginner Astrophotography Setup: Camera, Lens, and Tripod
If you want to take wide-angle photos of the Milky Way, stars, and constellations, a basic DSLR camera and lens on a tripod will do just fine. Even entry-level DSLR cameras are capable of capturing dim stars and DSO (deep-sky-objects) in a 30-second exposure. This is a great way to start learning the basics of night photography using long exposures.
This “Entry-Level” DSLR camera from Canon is capable of incredible astrophotos, both wide angle landscape, and deep-sky imaging through a telescope. Canon cameras are a favorite among astrophotographers, myself included. A standard kit lens such as the 18-55mm f/3.5-5.6 IS will yield some impressive images at it’s widest range of 18mm. However, if you are looking for an affordable upgrade to the standard lens, the Rokinon 14mm F/2.8 is a great choice.
If decide to purchase your first Canon DSLR camera, you are well prepared for many adventures in astrophotography in the future. When you are ready to start imaging deep-sky objects through a telescope, Canon cameras support a wide array of accessories and adapters to connect to virtually any setup. The camera can be astro-modified, and accepts an assortment of filters to help you get those most out of your imaging sessions.
The Rokinon 14mm F/2.8 is a great performer considering it’s affordable price tag. This astrophotography lens comes highly recommended from users who shoot nightscapes including the Milky Way. The crew over at the AstroBackyard Facebook Page noted just how sharp this lens is, and that coma and vignetting issues are not overly present.
A wide-angle camera lens like this allows you to capture a giant swath of the Milky Way in one shot – even without a full-frame camera. The fast aperture of F/2.8 means that the Rokinon lens lets in much more light than a standard F/4 camera lens. A faster aperture means recording more stars, in a shorter period of time.
A sturdy tripod is very important when photographing images at night. The camera must be completely stable to avoid blurry or moving stars. It is also important to choose a tripod with a flexible ball-head, so you can easily point the camera towards the sky. A quality tripod will safely hold your camera a lens without worry. A good will last you for years, so don’t skimp on your budget for this item.
You will likely be traveling with your astrophotography equipment, to set up under dark skies and for planned compositions of celestial events. A lightweight tripod built from carbon fiber will make these trips more enjoyable as they are strong yet easy to carry.
Astrophotography with DSLR camera on a Tripod (no tracking)
The photo below is a good example of an image you can expect to capture using a DSLR camera and tripod with no tracking. This photo was shot using a Canon 17mm F/4 Lens, a wide-angle lens. Several 30-second exposures were captured and manually stacked in Adobe Photoshop.
Beginner Astrophotography Setup – Deep-Sky Imaging
A stationary camera and tripod is capable of beautiful wide angle shots of the Milky Way and constellations, but what if you want to take close-ups of galaxies and nebulae? Deep-sky imaging adds another level of difficulty because it involves taking long exposures of moving objects in space. Well, we’re moving, the rotation of the Earth means that we need to move with the objects we are trying to capture.
Deep-sky imaging is the area of astrophotography that caught my attention, and where I spend the majority of my time. Below you will find everything you need to get started, including the equipment I personally used with great success.
An Astro-modified Canon T5i will capture the intense colors of nebulae including the red emission data ignored by stock cameras. Modifying a DSLR camera for astrophotography can be done yourself using a tutorial, or by a professional. The Canon T5i is one of the latest DSLR’s in the Canon Rebel line-up and a top contender for best beginner astrophotography camera.
I currently use a modified Canon Rebel T3i, an earlier model of this camera. The controls and features of this camera become very comfortable after a short period of time. This camera works well with a camera control software known as BackyardEOS – built specifically for deep-sky astrophotography.
This is a wide-field apochromatic triplet refractor. The Explore Scientific ED80 was built for astrophotography, and the results speak for themselves. Using your DSLR camera with this telescope will produce incredible photos of large deep-sky objects such as the Andromeda Galaxy and North America Nebula. Read my review of the Explore Scientific ED80 Here.
I will always recommend a small apochromatic refractor telescope to those who wish to get started in deep-sky astrophotography. This type of telescope has many advantages over the other designs in terms of portability and ease of use. If you looking to purchase your first astrophotography telescope, visit the following section of my website:
Connecting a DSLR camera to the telescope:
To connect a DSLR camera to your telescope you will need a t-ring and t-ring adapter. The rings attach to your DSLR body just as a regular camera lens would, and the t-adapter threads into the ring. These adapters come in 1.25” and 2” sizes to accommodate your telescope’s focuser draw-tube.
Your mount is the single most important piece of your gear. A quality mount will last for years of outdoor use in a variety of elements and temperatures. You will not be able to take sharp pictures of deep-sky objects without a tracking mount that has been polar-aligned.
The Skywatcher NEQ6 is a superb choice for beginners because it is easy to use, affordable and a proven performer. With proper autoguiding, this mount can easily take exposures of 10 minutes or more. This mount has a payload capacity of 18kg, more than enough for your telescope, camera, and accessories.
Autoguiding is the act of using a separate “guide camera” to track a star and keep the telescope focused on your target. It compensates for periodic error in the telescope mount and can help you shoot much longer exposures.
The kit from Orion includes the Starshoot autoguider camera and 50mm guide scope. This little combo works wonders for imagers using refractors on an equatorial mount such as the SkyWatcher NEQ6.
Running the Equipment:
A portable laptop computer is required to run the camera and autoguiding software. There is a software called BackyardEOS that was built for controlling your DSLR during a night of astrophotography. For autoguiding, PHD guiding 2 is a free software that works well with the Orion autoguider package and the tracking mount.
Although the Explore Scientific ED80 telescope has a flat field due to its triplet design, the edges of your frame may still show elongated stars. This can be corrected by using a field/flattener. This adapter threads onto your existing t-adapter to help “flatten” the edges of your image field. The model I use is a 0.8 X flattener/reducer, which reduces my telescopes focal length and aperture for a faster/wider view.
Your telescope’s objective may develop dew on its surface due to a change in temperature. This usually happens when the temperature cools off at night. Dew heater straps and a controller can eliminate moisture on your telescope lens by gently heating it. These straps simply wrap around the telescope around the objective.
Capturing Images with a DSLR and Telescope
With the right gear, you are now able to capture images of deep-sky objects, up close. DSLR astrophotography involves taking several long exposures to capture enough light from a dim object in space to show color and details.
Certain objects are apparent right away, while other DSO’s are very faint and require multiple hours worth of imaging to properly capture. If you are an astrophotography beginner, I would suggest choosing a bright target from the list below:
To photograph a sharp image of your target, your equatorial telescope mount will need to be polar-aligned. For observers in the Northern hemisphere, this task is made much easier by using the “North Star” Polaris to align your mount.
Polar alignment ensures that your telescope mount turns at the same angle as the rotation of the Earth. By aligning the axis of the mount with this rotation, you can effectively “freeze” the object in space to photograph it.
A camera sensor can record much more light and detail than our eyes can. By exposing a deep-sky object in the night sky to the sensor for a long period of time, the dim object becomes bright and colorful. This is why you have seen beautiful images of nebulae full of color, but can barely see a thing when you look through a telescope visually.
Without tracking, you will record start trails after about 30 seconds
With the telescope now moving on the same axis as the spin of the Earth, we just need to make sure that the camera and telescope lock-on to our subject. This is where autoguiding comes in. Using a software called PHD Guiding 2, we can use the laptop to communicate with the telescope mount and make adjustments to the tracking.
It is important that these images are properly exposed, and contain sharp details including the stars and the deep-sky object. The tracking, polar alignment and autoguiding will take care of the sharpness, but the exposure of each image frame is another story.
As a rule of thumb, the data should appear to the right ¾ of the histogram. This is the “sweet spot” where a good amount of photons have been collected, without clipping and overexposing your shot. Certain bright nebulae such as M42 can be “blown out” in exposures of 1 minute or even less, due to their extreme brightness.
FWHM in BackyardEOS
There are a number of ways to focus your camera through your telescope. My personal favorite way is the FWHM method built into BackyardEOS. This feature displays a number on the screen indicating how small the image of the star is. The smaller that number is, the tighter your focus.
Another way to achieve a sharp focus is by using the live view function of your DSLR camera. With a bright star in view, turn your camera’s ISO all the up to the maximum. You should see the out-of-focus bright star or several. Using the 10X zoom, manually rotate the focus until the star is as small as possible. Take a few test shots to be sure.
Capturing Multiple Exposures
By taking multiple exposures, we can stack all of the data on top of each other to improve the signal-to-noise ratio. This means that we are improving the signal (The light from the DSO) and reducing the thermal noise created from the camera. Noise can vary depending on camera model, temperature, and ISO setting.
Noise is the enemy of DSLR cameras and precautions need to be taken to reduce it. One effective way of removing noise in DSLR astrophotography is to use the dither function found in BackyardEOS. This will shift each frame slightly after each photo is taken. By shifting each frame, the noise is layered in a random pattern that smoothes out much of the color mottling and noise found in the frames.
Support Files: Darks, Flats, Bias
We can dramatically improve our final image by taking support frames such as darks, flats and bias frames. These are separate photos we need to take that will help during the stacking process. They are all relatively easy to acquire, much easier than taking the actual “light frames” of the deep-sky-objects.
Stacking and Processing an astrophotography image
The software I prefer to use for stacking my astrophotos is free. It is called DeepSkyStacker and does a great job a creating a master file of your image. The software calibrates and registers all of your exposures into a single file that you can process in Adobe Photoshop.
This is where you will load in all of the support files I mentioned earlier. Dark frames do a great job at reducing the amount of noise in your final image. Flat frames can even out the gradients and vignetting in your background sky. They also cancel out any dust or particles that were recorded by the sensor.
Post Processing in Adobe Photoshop
Arguably the most exhilarating part of the entire astrophotography process is post-processing your image in Adobe Photoshop. This is where you will really start to see your hard work and dedication pay off as your image takes shape. The power of Adobe Photoshop is in its layers and actions. Drastic changes to the levels and curves are made, while subtle boosts in saturation can bring out the true beauty of your target.