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I’ll walk you through the most powerful software in astrophotography, PixInsight! Join me as we work on the Orion Nebula showing off the impressive features of this program. Please like this video and join our growing community of amateur astronomers by subscribing to this channel. Let me know what you like about PixInsight and any other software you enjoy using for astrophotography.
Imaging the nighttime sky can be one of the most rewarding things to do in astronomy. When the light from deep sky objects that are thousands to millions of light years away hits the sensor of your imaging equipment it begins the wonderfully rewarding journey of imaging the heavens above. Today, I’m going to walk you through the techniques I use to properly image these objects and explain how to take Light, Dark, Flat and Bias Frames that can later be stacked and processed to bring out incredible details. To show each step of this process, we will be imaging one the best targets in the night sky, the Orion Nebula. If you have an interest in astronomy and astrophotography please subscribe and let me know about your questions and any techniques that you use to capture these images in the comment section below. Let’s begin with the most critical part that everything else depends upon, capturing the best light frames we can of our deep sky object.
How to Take Light Frames
Canon SL2, Samyang 135mm Lens, iOptron SkyGuider Pro
Light frames are the most important part of this entire process because they are the images of the actual object you are capturing. Nothing after this step matters unless you have solid usable data of the object you are imaging in the night sky. The more light frames you can capture the better your signal to noise ratio will be for your target once we stack these frames together using a program like DeepSkyStacker. For example, if I take 60 one minute exposures and stack them together to one hour of data it can nearly achieve the same signal to noise ratio as one long one-hour exposure would once we’re done with the whole process. This will lead to finer details showing up in the final image during post processing. A good resource that goes into incredible depth on these topics is “The Deep-Sky Imaging Primer” by Charles Bracken. I read this book a few years ago and it greatly improved my understanding of astrophotography and I’ll be sure to leave a link to it in the description below. I capture my light frames using a DSLR, Samyang 135mm lens and the iOptron SkyGuider Pro Tracking Mount. There are three main things we want to do to help us capture excellent light frames and those are making sure our camera is set to RAW, achieving sharp focus and choosing the proper exposure length. Without sharp, properly exposed light frames shot in RAW Quality with its incredible amounts of data there really is no use for what comes next in the process.
If you are interested in more info on DSLR Settings for Light Frames
To capture our light frames, let’s start by setting our camera to Manual Mode and RAW Quality. Next, let’s work on getting sharp focus for our light frames by focusing our equipment on the brightest star we can find. One thing that can help you with this is a Bahtinov Mask. After placing it over your camera lens, slowly adjust focus until the center spike is perfectly between the other two spikes. Now that we’ve set our camera to RAW and have adjusted focus, let’s turn our attention to getting a proper exposure of our target, for me tonight, that’s the beautiful Orion Nebula. For the DSLR I’m shooting with, I’ve set the ISO to 400 and my Samyang 135mm lens has its F-Number set to F/2.8. Now, we need to test out different exposure lengths to see which one will work best for our target. Let’s test out different exposures for our light frames by taking 15 second, 30 second, 45 second and 1 minute exposures. To determine what exposure works best, I’m going to press the info button to see the difference in the histogram for each image.
The histogram is your friend in astrohphotography!
The trick is to get a histogram that is about 3/4 of the way over to the left. Too far to left and you don’t have enough difference between your object and the background of space, too far to the right and you may lose some of the brightest details of your object from the data getting clipped off. Tonight, it looks like the best exposure for me will be somewhere around 20 seconds. This again will vary greatly depending upon what object you are imaging, the light pollution of your area and the capability of your tracking mount. Now that our camera is set to RAW, we’ve achieved sharp focus and determined the best exposure length it’s time to actually shooting our light frames. Remember, these are the most important part of the imaging process, the more light frames you capture and the higher their quality the better your signal to noise ratio will be thus revealing more detail in your final stacked and processed image. To assist you in capturing your light frames, use something like a remote shutter release trigger to set how many exposures you want and how long you want them to be. My goal tonight is to capture at least 200 separate 20 second light frames of the Orion Nebula before it lowers into the light pollution dome of a nearby city. Once I’ve double checked that the first few light frames are sharp and properly exposed, I head inside for about an hour until it has finished capturing them.
In Summary: Light Frames
How to Take Flat Frames
The White T-Shirt is your Friend for Flat Frames
Now, our attention turns to the process of taking different types of additional frames that will later be used to correct imperfections that can show up in our light frames. I’m going to begin this part of the process by capturing the flat frames. Flat Frames will improve the quality of our image by removing unwanted differences in brightness, such as vignetting and dust shadows on our sensor. To get rid of these imperfections, Flat frames need to be evenly illuminated throughout the field of view and to accomplish this I like to use a sophisticated scientific instrument known as the white t-shirt. Begin by making sure your imaging setup is in the exact same orientation as it was for the light frames and make sure you are still shooting in RAW quality with the same ISO and F-Number as before. The only thing you will want change on the camera is the mode from Manual to AV. Carefully stretch a white T-Shirt over the lens hood, making sure there are no wrinkles. Once that’s done you are going to need a light source to evenly illuminate it. I like to use a white background on my iPhone with the brightness turned up to 100 percent. With both of those things in place, press the shutter to take the Flat Frames. Since you are shooting in AV mode, the camera will make sure everything is properly exposed with the histogram peaking near the middle. As for all these frames, the more the merrier, but there is a point to which you get diminishing returns on how much they will improve things. I normally shoot between around 75 Flat Frames.
In Summary: Flat Frames
How to Take Bias Frames
No Light Needed
Our next type of frame is the quickest to shoot and simply requires you to place the cap on your lens so that no light whatsoever shows up in your frames. These will improve our image by removing the bias signal and read noise from our sensor. Switch your camera back to Manual Mode and be sure to keep the same RAW Quality and ISO you’ve used all night. Go into your settings and select the fastest shutter speed available for your camera. For this camera that’s 4,000. Press the shutter and easily capture your bias frames. I normally aim for around 75 of these as well.
In Summary: Bias Frames
How to Take Dark Frames
No Light Needed
Finally, we have our Dark Frames. These will improve our image, by removing the thermal signal of our sensor and any hot or cold pixels. Like Bias Frames, they require you to keep the lens cap on to keep things dark, but the key difference for these is that you need to take them at the same exposure length as your light frames captured earlier in the night. For me tonight, that was 20 seconds. Make sure you are still shooting in RAW Quality with the same ISO as well. The exposure length and ISO are critical for Dark Frames because we want the camera’s sensor to be as close to the temperature as it was when it was taking the light frames a few minutes earlier. What I would suggest you do is keep your equipment setup just as it is outside and use your remote shutter release trigger like before to capture your Dark frames at the same length as your light frames earlier in the evening. Now, the temperature will change slightly throughout most nights, but this is a nice way to match the temperature of your sensor from earlier in the evening as best you can. I normally try to take between 75 and 150 Dark Frames depending on how long my exposure times are, changes in outdoor temperature and how early I’d like to get to bed.
In Summary: Dark Frames
I hope you’ve found this article helpful on how to capture the best Light, Dark, Flat and Bias Frames possible. Check back soon for my video on how to put each of these frames to use by stacking them in DeepSkyStacker. Once it’s released, I’ll tag it and place a link in the description of this video. If you have any questions or suggestions on how improve these imaging techniques, please let me know in the comment section below. Thank you all so much for your support and clear skies for Late Night Astronomy.
DSLR’s are wonderful to use for astrophotography. Whether you’re just getting into imaging by shooting star trails on a tripod or you’ve begun taking breathtaking pictures of deep sky objects with a tracking mount, DSLR’s are an impressive piece of equipment in amateur astronomy. Today, we’re going to look at the best camera settings that will help you maximize the quality of your nighttime photography with a DSLR
Step 1: Manual Mode & RAW
I’m currently shooting with is the Canon SL2 and while the menu system will obviously vary between companies and camera models the settings we are going to be discussing today should be fairly universal for most DSLR’s but always be sure to test things out for your camera before you get started with a long late night of imaging deep sky objects. Let’s begin by making sure your DSLR is in Manual Mode. This will give us the most flexibility with altering settings and controlling all aspects of how the camera is capturing our target. Once you’ve done that, go into the menu system and change your image quality to RAW. This is by far the most important setting in your menu to double check before each imaging session. RAW is such an important setting because of the amount of data it saves of the photons hitting your sensor. It’s sometimes referred to as a digital negative due to the large amount of data it saves. Increased information for variances in brightness, color and dynamic range will lead to more flexibility down the road for stacking and post processing when you are attempting to bring out the great dynamic range of a nebula like Orion or the subtle faint blue details surrounding the Pleiades Star Cluster.
Step 2: Various Menu Settings
Next, let’s go and change some other settings in our menu system and we’ll continue by setting our Picture Style to Neutral and White Balance to “Daylight”. These two settings won’t have an impact on the actual files being saved since we are shooting in RAW but they can have an impact on the histogram you will be analyzing when you are finalizing how to image your target when we get to that portion in a few minutes. We will also change our High ISO Speed to off. Since I plan to shoot dark frames later in the night, this feature is not needed. Another setting I like to disable is sensor cleaning. You will want the light, dark, flat and bias frames you will be capturing later in the night to be consistent and if your camera were to turn off and do a self-cleaning of the image sensor that could change any imperfections on the sensor from one shot to another. This will allow us to clean up those imperfections more easily with post processing. I’ve also found it good practice to have image review set to off and drive mode set to single shooting. Be sure to switch your camera’s lens to Manual Focus as well so you can fine tune the focus using the naked eye or something like a Bahtinov mask to assist you when imaging your target. Again, be sure to test these camera settings out because they can vary between brands and although things like shooting in RAW and using Manual Mode are universal practices other things may slightly vary in name or function but for my DSLR these settings have worked very well for me over the years!
Step 3: F-number
The final three settings we’re going to look at are the critical final steps before you begin capturing large amounts of data throughout the night for your target and they also vary greatly depending on your specific camera and lens. Let’s look at what you should consider when determining your DSLR’s F-number, ISO and Shutter Speed for deep sky astrophotography. Your options for F number will depend upon what lens you are using. The lower the F-Number the more light it will let in. More light is obviously good for capturing the night sky, but it may be a good idea to stop your lens down from let’s say f/2 to f/2.8 to sharpen the image a bit. Sometimes stopping down the F number can even be an artistic choice. Even though my Samyang 135mm F/2 can get sharp stars fully open at F2, I will often choose to stop it down to f2.8 because I like the spikes that come off bright stars from the blades of the aperture at that f number. I would suggest starting with your lens fully open and then do some test shots to check the focus from edge to edge of your frame and consider stopping down if you aren’t pleased with the initial results.
Step 4: ISO
Next, we need to figure out the ISO to use for our DSLR. Now, how to exactly describe what the ISO does to the sensor of a DSLR is a complicated topic that I would like you all to help me with in the comment section below. I’ve always thought of changing the ISO as adjusting the sensitivity of the sensor. This doesn’t magically allow your camera to collect more light and increasing the ISO too much can negatively impact the dynamic range of your final RAW image. Also, ISO settings affect DSLR sensors differently, so this isn’t a one size fits all setting. Simply put, I have experimented with my camera’s ISO settings ranging from 100 to 1600 ISO imaging a wide variety of deep sky targets and have found my cameras sweet spot to be ISO 400. Anything higher and I tend to lose too much dynamic range when I go to processing and anything less can leave streaks and banding effects from the sensor itself. Experiment with this and do some additional research for your specific DSLR to find out if others have discovered what works best for your sensor.
Step 5: Shutter Speed
Lastly, we need to figure out what to set our shutter speed at so photons can fill up our sensor and create beautiful images of the nighttime sky. This will depend partially on what additional equipment you own. Are you shooting on a tripod, a smaller mount like the Sky Guider Pro or have you invested in a couple thousand dollar tracking mount? For the benefit of this video, let’s assume you are testing the waters of astrophotography and have a tripod or entry level mount like the Sky Guider Pro I own. For a tripod, go out and shoot some beautiful star trails. Point to a part of the sky, adjust your focus and experiment with how long you can keep your sensor open to get different effects from the star trails. Play around with what your camera can do and try to find Polaris to see how much it does or doesn’t move compared to the other stars in the sky. A nice tool to mention real quick that doesn’t cost that much money is a remote shutter release trigger. The one I own allows me to set the shutter speed of the camera and how many pictures I want it to take. Connect it to the wire remote port on your DSLR type in your settings and you can head back inside for a bit while the camera works its magic imaging the night sky. For those of you with a polar aligned tracking mount the decision of shutter speed becomes more exact. With your F-number already set on your lens go outside and do some test images at various shutter speeds and ISO’s if you haven’t determined if your camera has an ISO sweet spot. For this example, I’ve adjusted my camera to every menu setting mentioned in this video, set my lens to F2.8, ISO to 400 and have taken 15 second, 30 second, 45 second, and 1 minute exposures. To determine what exposure works best, I’m going to press the info button to see the difference in the histogram for each image. The trick is to get a histogram that is about 3/4 of the way over to the left. Too far to left and you don’t have enough difference between your object and the background of space, too far to the right and you may lose some of the brightest details of your object from the data getting clipped off. This again, will be something you will need to experiment with depending on your lens, ISO and the maximum practical exposure length that your tracking mount is capable of. Most of the image I shoot on my Sky guider Pro, with a 135mm Samyang lens at F2.8 and ISO 400 have an exposure length between 30 and 90 seconds depending on what I’m imaging, the light pollution of my area and what the histogram is telling me about the data I’m collecting for future stacking and post processing.
What DSLR settings work best for your camera for astrophotography? Please be sure to help each other out with questions and suggestions regarding all your different types of imaging equipment in the comment section below. Thank you all so much for your support and clear skies from late night astronomy.
Let’s unbox, review and test this lens to find out why it is one of the best bang for your buck deals in astrophotography! I’ll walk you through all this incredible lens has to offer as we go outside to test it with some deep sky imaging. If you own the Samyang or Rokinon version of this lens please let me know about your experience using it and what your imaging in the comment section below.
One important thing to mention off the bat regards the confusion over any differences between Samyang and Rokinon lenses. From what I’ve read, the 135mm f2 versions of each lens are identical. The difference in their names simply comes down to a marketing decision. If both are available to buy where you live, do what I did and go with the cheaper one, that ended up saving me about 20 dollars for this the Samyang model.
When researching what lens to buy for astrophotography, there were several things that led me to this Samyang Lens. One of which was its low F number. At F/2, this has a very large aperture which lets in a tremendous amount of light, leading to fainter objects showing up under ideal imaging conditions and shorter individual exposure times needed to collect light for stacking and post processing. The true beauty of this lens comes from the fact that even shooting at F2, you can still get incredibly sharp images across the entire field of view and that’s not always the case for lenses.
The second thing that sold me on this lens was the fixed 135mm focal length. Prime lenses that don’t zoom often lead to sharper results for astrophotography due to the design of the lens. 135mm is also a nice sweet spot for my current tracking mount. At a little less than 2 pounds, its light enough for my Skyguider Pro and the amount of sky that it can image will reveal faint details of impressive deep sky objects but also doesn’t push the limits of what my tracking mount is capable of in terms of its tracking accuracy at long exposure times.
Few things test a lens like imaging the nighttime sky with its pinpoint stars and faint deep sky objects, so let’s put this lens to the test and see if it’s impressive claims match up to the real-world rigor of astrophotography by imaging the Constellation Orion. Now the detail of your images will vary from mine due to things like light pollution, exposure times and post processing but the thing I really want to point out is the sharpness of this lens, fully open at F2. From the Flame and Horsehead nebulas near the bright star Altinak, to the Orion Nebula with its nursery of dynamic gas clouds creating stars all the way over the extreme edge of the image where faint stars shine bright, this lens remain as sharp as the center of the image across the entire field of view. The Samyang 135mm F/2 easily lives up to its hype and should be near the top of your list of purchases if you are new or experienced in the field of astrophotography.
If you’re using or are looking to buy the Samyang or Rokinon 135mm F/2, please let me know what you’re imaging with it or any questions you may have in the comment section below. Thank you all so much for your support and clear skies from Late Night Astronomy.
In this video, I’ll show you how to quickly find Polaris and use it to polar align your tracking mount for a great night of astrophotography. What equipment do you own for astrophotography? How do you go about achieving polar alignment? Please let me know of any tips and tricks you use in the comment section below!
Have you ever wanted to take a picture of Saturn using your telescope and camera? This video will walk you through each step of the process. From equipment, to capturing footage, to using free software that will help you create incredible images of Saturn!
As Mars nears opposition, I’ll show you a step by step guide to take incredible images of the red planet using your telescope and free software. Please let me know about your questions and experiences observing or imaging Mars in the comment section below.
On a cold but crystal clear 28 degree night, I balanced and aligned the SkyGuider Pro, attached my DSLR and focused in on the Orion Nebula, a target I had been waiting to image since first getting into astrophotography.
Located roughly 1,300 light years away, the Orion Nebula is one of the closest stellar nurseries to our planet. It’s impressive size and gorgeous colors makes it one of the most viewed and photographed objects in the night sky. This 50 minute exposure is beyond what I expected to get for my first attempt at photographing this beautiful nebula.
With one hour and twenty minutes of exposure and several hours of processing, I have finished my work on the Pleiades Star Cluster. Also known as the seven sisters, its stars are surrounded by blue nebulae, which are difficult to see in a telescope but easily visible through long exposure photography. As the blue stars move through these dust clouds, their light reflects off of them creating the nebulosity in this image. I am really pleased with the faint details of the clouds and their complex structure.
Late Night Astronomy 