If you’ve ever thought about getting into astrophotography, you may have been dissuaded by the task of correctly processing your own images. There are countless guides online using a variety of programs, but they are either expensive and difficult to use, or are only available for a single operating system.
I’m not talking about processing milky way shots with a wide-angle lens here, but true deep sky objects, nebulae, galaxies, etc. That kind of processing requires specific programming, of which our traditional tools (like Lightroom and Photoshop) are woefully incapable. You may have heard of programs like Deep Sky Stacker, or PixInsight, which are extraordinary in their own right, but one is Windows only, and the other has a considerable price tag. Is there a happy medium? A program that is easy to use, works on MacOS and Windows, and is free?
Absolutely. And I have been urging people to consider its use for the past couple of years. In this video, I talk about Siril, a free, multi-platform astrophotography processing software that eclipses its free competitors, and with its robust features, stands up to the paid ones as well. What’s remarkable about Siril, is that it checks so many boxes for the hobbyist, while having features that even seasoned astrophotographers can only find in paid programs, or action sets and plugins for Photoshop. The first half of this video is dedicated to using Siril and its many processes, of which can only be found in the more advanced astro processing programs. Tools like photometric color calibration, background extraction, subtractive chromatic noise reduction, and automated stretching, are necessary steps in astro processing, but until recently, have not been available outside of paid programs. The second half of the video is dedicated to processes using only the tools in Photoshop, no extra plugins or action sets are required.
I made this video as a project to see if it was possible to get similar results using free software. The requirements were that it had to be easy to use, free, and could work on both MacOS and Windows. I realize that Photoshop is only one of those things, but most people who get into this hobby are photographers looking to expand the use of equipment they already own, and an overwhelming number of us already use Lightroom and Photoshop. But if you don’t have an Adobe subscription, Siril can work for you too, because it can also process images, and there isn’t an absolute need to venture into another image processor after you have finished with Siril.
There are two things a camera should have to be good at astrophotography: a large image sensor and the ability to manually control camera settings. Yet somehow, the Google Pixel 6 Pro manages to capture stunning astrophotographs with the press of a single button. The image sensor, though much bigger than previous iterations of the Pixel line-up, is still tiny in comparison to mirrorless or DSLR cameras. But it’s the powerful machine-learning software within that makes the Pixel 6 Pro so good at capturing the stars.
So just how does Google’s latest flagship smartphone manage to produce photos that are star-studded, with minimal image noise and stunning clarity? I decided to put the Google Pixel 6 Pro to the test, focusing on a few key areas. I’ll be taking into account its ease of use, how Artificial Intelligence (AI) processes photos to clean things up, its color handling ability, and I’ll also take the photos into post-processing software to see whether it’s better to shoot JPEG or switch over to RAW — the results might surprise you!
While PetaPixel has given the Pixel 6 Pro high marks overall and currently lists it as the best smartphone to leverage computational photography, in my eyes, it is also probably the best smartphone you can buy right now to capture night sky images. I realize not everyone buys a smartphone for this ability, but for those stargazers who want the convenience of astro shooting in their pocket, then this smartphone is the one to go for. For my money, the Pixel 6 Pro is not just a stopgap before you reach for a mirrorless or DSLR, it’s probably the fastest and easiest way to capture the galaxies with crisp precision.
Gone are the days of setting up your mirrorless or DSLR, squinting at the screen as you try to pinpoint focus on a dim star in the sky. There’s no need to calculate aperture, shutter speed, and ISO sensitivity, or warm up the lens barrel before shooting. All you need is the Google Pixel 6 Pro and a tripod.
Shooting astrophotography with the Pixel 6 Pro is an absolute doddle. There are two options for shooting in low light with the smartphone: Night Sight mode and Astrophotography mode. They each aim to overcome specific problematic shooting conditions.
Night Sight, which has been around on Pixel smartphones since 2018, works by using Artificial Intelligence to create well exposed low light scenes when shooting handheld. It looks for camera shake blur, motion blur, and other issues such as high image noise, and then works autonomously to remove them from the final shot.
Astrophotography mode, however, only appears when using Night Sight and the phone is completely still. It’s best to mount it to a tripod (I’ve used the Joby Gorillapod and accompanying phone holder with my Pixel 6 Pro) but you could also just prop it up on a rock.
Here are how to access both features:
Night Sight Mode
Open the Camera app
Swipe between modes at the bottom of the screen, navigating to the Night Sight option
The shutter release icon will turn into a crescent moon, tap this and hold the phone as steady as you can while it captures the photo
Navigate to Night Sight as above
Make sure the phone is on a tripod or propped up against something and remains completely still
The crescent moon shutter release icon turns to stars, tap it to capture an astrophoto
Wait up to four minutes for the exposure to finish
One thing I really like about the astrophotography mode is that it displays a countdown timer on the screen. By counting down the exposure time, the average user is free to think about other things, rather than concentrate on technical settings such as shutter speeds and ISO. For pros who like shooting in manual mode this lack of control might be a little frustrating, but let’s face it, if you’re going to be shooting professional-grade astro images you’re not going to be relying on a smartphone.
Another great feature is the level which appears when the phone reaches near-level. It appears as two lines, one labelled by degrees of how far out of alignment the phone may be. If you hit 0 degrees (completely level) then the Pixel vibrates slightly which makes it easy to get horizons dead straight without faffing.
Overall, color handling is good in the Pixel 6 Pro. The majority of the time the white balance is spot-on and does an excellent job at riding the fine line between reducing light pollution and keeping colors realistic. Occasionally though, it’s a little inconsistent. Swivel the camera round and take four or five different astro shots and you’ll likely end up with two or three different white balances. For example, a shot including the skyline of a distant city will produce a much warmer photo than one taken straight up at the stars with no foreground.
Tapping the scene while shooting provides on-screen sliders to control highlights, shadows, and the color temperature. Though, if you’re in astro mode the movement from the vibrations from the tap will likely send it into Night Sight mode, so you’ll have to wait a few more seconds before it switches back. It’s a shame that the astro mode isn’t an option you can lock into like Night Sight is, and is definitely something I’d like to see added in a future update.
JPEG vs RAW
The magic of Google’s new Pixel phones cameras isn’t in the hardware, even if it’s been updated for the latest line-up, but rather resides in the sophisticated AI-powered software that processes the images. I’m incredibly impressed by the Pixel 6 Pro’s JPEG handling when shooting astro as it reduces image noise astonishingly well, balances colors evenly, removes color artifacts, and also applies lens corrections to remove vignetting and lens distortions.
However, the phone does also offer the ability to shoot RAW files alongside JPEG. Normally when shooting any kind of photography, I always opt for shooting RAW and rarely bother with JPEG capture. But Google has done such an excellent job at automatically addressing imaging issues in the astrophotography mode that I’m considering making an exception for the Pixel 6 Pro.
These three photos below show the difference between the Google Pixel 6 Pro’s JPEG image, straight out of camera, a processed RAW version, and those same processed settings applied to its JPEG image. Personally, I think the processed JPEG looks the best:
I imported the RAW files to Lightroom Classic and went about my usual processing techniques to remove noise, get good color balance, and let the stars shine, but I found that I couldn’t process the image as clean as the JPEG file it produced on its own. No matter what I did in Lightroom Classic, I was still left with some color artifacts and image noise. That said, I was able to tease out more detail in the RAW files as is to be expected. Sadly though I wasn’t able to make lens corrections due to the fact Adobe has not yet to incorporate the profile into Lightroom Classic.
After synchronizing the settings between RAW and JPEG files I think I actually prefer the look of the JPEG. I think this is all due to Google’s imaging algorithms whirring away in the background tweaking the shots during capture, but if it works, it works.
Areas That Could Be Improved
What is the first thing you think of when picturing astrophotography? If you’re anything like me, it might be a beautiful, wide vista with an expansive sky overhead. The Pixel 6 Pro’s new ultra-wide lens would be ideal for this kind of photography, but unfortunately, astro mode can only engage when using the standard lens at 1x or 2x zoom.
It would be great to utilize the new ultra-wide lens for astro to fit more of the night sky into frame, and perhaps this is something we’ll see in future editions of the Pixel line. Disappointing though it is for the Pixel 6 Pro, it’s not a deal-breaker. As you can see from the example images it still captures a decently wide field of view on the standard lens.
It would also be good to see and set color temperature values when capturing astro shots, which would benefit the cohesiveness of not only a series of shots but also the timelapse function.
The phone is susceptible to some lens flare and glare from light sources, even though in-built software is designed to intelligently reduce this as much as possible. This isn’t much of a problem when shooting during the day, but becomes more apparent with the longer exposures required for night photography. Passing car lights or flashlights easily flare across the lens, spoiling astro shots. While a lens hood would probably be asking a bit much of a smartphone, it would be nice to see some kind of improvement on lens shielding.
Stellar Results for a Compact Camera
A look at the price for the Pixel 6 Pro reveals that it’s extremely competitive at just $899. Price, along with the sheer number of incredible features the Pixel 6 Pro has including 4x optical zoom, an ultra-wide lens, and fantastic low light/astro shooting features means I can’t see why anyone would voluntarily opt for a compact point-and-shoot camera these days where convenience is paramount.
Overall, for a smartphone that can shoot astrophotographs as competently as this, the Pixel 6 Pro can’t be beaten. This is certainly its specialty and it performs extremely well. I’m sure with future software updates we’ll see this pushed even further, especially now that Google has a smartphone with new camera hardware and the self-created Tensor chip living inside.
Astrophotography feature makes shooting easy
Excellent processing removes image noise
Limited to four minute exposure
Heavy vignetting around edge of frame
Should You Buy It?
Yes, especially if you’re looking to upgrade your smartphone and are thinking of purchasing a point-and-shoot camera for astrophotography. There’s no need to get those two devices separately if you opt for this smartphone, and you’ll probably save a bit of money too. Thanks to the smart processing in the Pixel 6 Pro and freshly updated camera hardware you can easily capture astrophotographs so detailed that the Milky Way and other galaxies, constellations, and more are within reach. And all from something that slips into your pocket.
Astrophotography has some specific and often more demanding requirements when it comes to lenses, and as such, it takes careful evaluation of potential options to know which is right for your work. For astrophotographers on a budget, there is the Viltrox 35mm f/1.8 AF, and this great video review takes a look at the sort of image quality and performance you can expect from it in practice.
Coming to you from Milky Way Mike, this great video review takes a look at the Viltrox 35mm f/1.8 AF lens, with a specific eye toward astrophotography. Even though the 35mm f/1.8 AF is quite affordable, it still comes with a range of useful features, including:
10 elements in eight groups
Two extra-low dispersion elements and two high-transparency elements for reduced chromatic aberrations and increased clarity and color accuracy
Two aspherical elements for reduced spherical aberrations and distortion and increased sharpness
HD nano multi-layer coating for reduced flares and ghosting and increased contrast and color fidelity
STM stepping motor for quick and quiet autofocus
Full-time manual focus override
Nine-blade diaphragm for smoother bokeh
Integrated micro-USB port for firmware updates
Check out the video above for the full rundown on the lens.
As we transition from summer to fall, two of the most photogenic planets, Jupiter and Saturn, have passed the point of closest approach (opposition) to the Earth for the year. Yet, they still make great targets for planetary astrophotography, especially since they are now high in the sky soon after sunset. As another bonus, photographing these planets does not require traveling to a dark sky site. This kind of astrophotography can be done from our backyards.
Saturn’s rings make it a favorite of astronomers, but Jupiter’s larger apparent size (due to its larger actual size and closer orbit), easily visible cloud bands and cloud swirls, and four bright moons make a more dynamic target for astrophotographers.
On rare occasions, these planets actually come close enough to be photographed together (a conjunction), as they did in late 2020. The composite shot below shows the two planets passing each other (from our viewpoint) over a few days, providing a convenient size comparison. The moons of Jupiter can also be seen in various positions around Jupiter. Our Moon was added to the composite as another size reference. It was not close to the pair during this conjunction.
The photo below is a single shot showing Jupiter and Saturn at their closest approach on December 21, 2020.
The photos above are examples of what can be done with a standard camera equipment (Nikon D850 + 2x teleconverter) coupled to a moderate-sized refractor (mine is a Japanese Borg 100ED, a 100mm diameter, f/6.4). The lower photo was shot with a Canon RP mirror-less camera coupled to the same telescope.
Shooting for Maximum Detail
When trying to shoot detailed shots of the planets, in many respects, planetary astrophotography is very different from most other types of astrophotography. Instead of taking longer and longer exposures, planetary astrophotographers try to take short (video rate) exposures and stack hundreds or thousands together to beat the natural distortions of our atmosphere. High magnification is also used compared to most other types of astrophotography.
To meet these goals, specialized equipment is necessary: a telescope to provide the high magnification is needed to start. Typically, this is a telescope which utilizes mirrors, which are less expensive in large sizes than a refractor. Amateur equipment typically goes up to 14-inch diameter (35 cm) reflecting telescopes. Refractors generally become impractical and too expensive beyond 6-inch (15 cm) diameters.
On the back end, a modern camera capable of shooting video (even a cell phone) can be used, but the tradeoff is loss of detail and dynamic range due to the 8-bit format and compression used in consumer cameras. The best solution is to use an astronomical “video” camera that features high dynamic range, lossless “raw” recording, and fast data transfer, usually to a computer via USB 3. A wide range of popular cameras are made by manufacturers QHY and ZWO in China.
Along with the specialized cameras specialized (but fortunately free) software is used to capture bursts of video. More specialized (and free) software is used to sort, align, and stack the captured frames. To sharpen and remove noise from the resulting stacked image, yet another free program is used to extract the highest possible detail from the image.
As mentioned earlier, planetary astrophotography generally requires taking high-speed but short bursts of frames, unlike deep sky astrophotography, which may take frames of a single target throughout multiple nights. The reason for this is that many of the planets are rotating so rapidly that stacking a long burst of frames will smear the final image.
Using Firecapture’s versatile capabilities also makes it easy to schedule regular bursts of frames, process each burst, and then assemble the resulting stacked frames into a time-lapse animation. Jupiter’s easily visible details and moons make the best target for this. In the example below, Jupiter’s moon Io is crossing Jupiter while casting a shadow on Jupiter. In the meantime, on the other side of Jupiter, the Great Red Spot (a permanent storm feature) comes into view.
Regular astrophotography of Jupiter can also yield some rare results. Recently an amateur astronomer was lucky enough to record a flash of light against the disk of Jupiter. This was probably a large meteor, estimated at 20 meters across, exploding in Jupiter’s atmosphere.
In some cases, longer bursts of frames need to be stacked as often amateur astronomers opt to use monochrome cameras with separate red, green, and blue filters for the highest resolution. In this case, three bursts of frames need to be taken sequentially, during which time planetary rotation can be unacceptable. In this case, another specialized program (Winjupos), will map the frames to a 3D model of the planet and stack the frames after “derotating” them to line them up properly.
Other Planetary Targets
Another favorite of planetary astrophotographers is Mars. At the closest approach, many surface details such as dark areas and polar caps are visible, but the instances of close approach (opposition) only occur about every 26 months. The next Mars opposition will be in December 2022. At the moment, Mars is on the far side of the sun relative to the Earth. However, later this year, Mars will become visible in the morning sky. It will be small but will be growing in apparent size as we approach opposition.
The remaining planets (Mercury, Venus, Uranus, and Neptune) have little or no features which show up in typical amateur telescopes, but photographing them all for your “collection” is a nice challenge. The family portrait below shows the planets as photographed over a marathon all-night (sunset to sunrise) session in July 2018.
Back in 2018, the planets were lined up in the sky as shown in the 180-degree panoramic shot below. At the time the panorama was made, Mercury had already set, and Uranus and Neptune had not yet come up in the East.
One thing to note in the planetary family portrait above is that Mars was close to opposition, so it appears very large compared to the other planets. Mercury and Venus show partial illumination phases at various times, appearing “full” when smallest. The range of apparent sizes (in arcseconds) of the planetary disks are:
Mercury: 4.5” – 13.0”
Venus: 9.5” – 66.0”
Mars: 3.4” – 25.1”
Jupiter: 29.8” – 50.1”
Saturn: 14.9” – 20.7”
Uranus: 3.3” – 4.0”
Neptun: 2.1” – 2.3”
For reference, the Moon and Sun are about ½ degree (1,800 arcseconds) in size.
Planetary Combo Opportunities
Because the planets are always moving against the sky and relative to each other, other photo opportunities to watch for are conjunctions (close apparent approaches to two or more objects) or even occultations (eclipses) of planets by the Moon. Jupiter and its moons also provide photo ops at certain times when the moons are occulted by Jupiter or pass in front of Jupiter, often also casting shadows on Jupiter.
In any case, if you’re looking for challenges in astrophotography, check out the planets.
Astrophotography has quickly become incredibly popular these days, with the advent of increasingly smaller and affordable star trackers, and not to mention the global pandemic, which has forced people to make do with photographing what is immediately around them, or above them.
If you are thinking about getting into astrophotography, or you already have, and are wondering about taking it to the next level but are unsure how to proceed, then this video is most definitely for you.
Nico Carver, better known in the astrophotography community and on YouTube as Nebula Photos, comprehensively breaks down five levels of astrophotographic equipment in detail. Starting with a humble smartphone and tripod, all the way up to a dedicated astrophotography camera, robust automatic tracking mount, telescope, and all the accouterments and gadgets that go with it, there’s a well thought out kit for every budget. And as you can imagine, the budgets increase exponentially, as does the complexity and quality of photos one can achieve as you progress through the various kits he outlines. As someone who is currently advancing through this field, I can personally vouch that the results are worth the expense in time and money if you are ready to tackle astrophotography with any seriousness.
I am constantly amazed though, by the quality of images that can be taken with the minimal amount of equipment, which seems to be Carver’s specialty. Astrophotography is an inherently frustrating realm of photography, and the steps needed to get the fantastic images you see on the internet are sure to scare away most hobbyists. But Carver does an amazing job in this video, and many others on his channel, at explaining that if done carefully, you can get amazing results with the smallest investment. Yes, even a smartphone.
Astrophotography is a tremendously challenging genre that requires some specialized techniques and knowledge, but when you nail a shot, the results can be jaw-dropping. If you are looking to improve your astro images, this excellent video tutorial will show you five great tips that will help you take better photos of the night sky.
Coming to you from Apalapse, this awesome video tutorial will show you five helpful tips for taking better astro images. Astrophotography definitely takes some very specific knowledge, techniques, and often equipment, but it can be entrancing to capture images of objects that are literally millions or billions of years old. If you are really serious about the genre, one essential piece of equipment you should eventually consider is an equatorial mount. These mounts work to counter the rotation of the earth and keep the sky still relative to the camera, allowing you to take much longer exposure without blurring, which is a huge boon in a genre where light is at a serious premium and you are often working with ultra-high ISOs and very long shutter speeds. Even the most inexpensive equatorial mounts will make a big difference. Check out the video above for the full rundown.
Are you a photographer who would love to give deep space imaging a try – but you’re not quite ready to spend thousands of dollars (or more) to build your own astrophotography rig? With remote astrophotography, you can create astonishing images without the high startup costs. You can learn how to capture and process images using high-end telescopes located all over the world.
Even if you have your own gear, remote technology can supplement what you already have. For example, you could improve your processing skills, capture images without light pollution, try out a variety of equipment options, or capture images from a different location or even hemisphere.
There is something uniquely satisfying about using your own equipment and software (plus some patience and skill) to capture a stunning image of a galaxy or nebula in deep space. However, as amazing as it feels to do astrophotography on your own, it’s also a hobby that can get, well, expensive.
First, the best celestial images require a high-end apochromatic refractor telescope or a fine-tuned astrograph reflector with precision-built optics. Second, in addition to the telescope for astrophotography itself, you’ll need a smooth computerized mount capable of being auto-guided with the help of a secondary guide scope. Third, you’ll need a suitable camera and several other accessories — for example, a dew control system, filters, reducers, field flatteners, correctors, et cetera.
Finally, you’ll need a place to set up your equipment. While you can certainly do deep space imaging in your backyard, it takes time and effort each time you want to set everything up and you may need to contend with light pollution or sky conditions, which can make things more challenging.
Also, one last thing: Even if you have excellent gear and a great place for imaging, your particular combination of equipment, location, and hemisphere will always limit what you can capture.
So, regardless of your situation, adding a remote option to your toolkit can help expand the imaging choices available to you.
So, How Does It Work?
With remote astrophotography, you collect your image data using a telescope set up in a remote location.
An observatory, usually located in a dark-sky location (whether an official IDA site or just a remote location with a very dark sky), houses the rig. The observatory allows electronic control of its roof, so you can remove it anytime for operation without anyone physically onsite at the observatory.
Here is how it works:
First, you submit an image request to the service provider, specifying your target and any other details required for capturing the image data.
Next, the computer-controlled equipment collects the requested exposures and sends you a file containing the raw (unprocessed) image data.
Finally, you use image processing software to “stack” and process your images to produce the final result.
A Great Way for Beginners to Experiment with Astrophotography
For beginners, remote astrophotography offers a great way to get started and learn some of the basics of imaging objects in deep space. You can focus your energy and initial learning on understanding the overall process, figuring out the optimal exposure settings, and converting the raw data into beautiful final images.
Sometimes people who are learning astrophotography spend a lot of time and money on equipment and capturing raw images, but they don’t spend as much time learning and perfecting the back-end of the process where the image “comes to life.”
With remote astrophotography, you can learn the entire process before investing in equipment, or you can do a mixture — use your own equipment while also experimenting with remote imaging so you can compare and optimize results.
But It’s Not Just for Beginners!
If you’re a more experienced astrophotographer, you can still take advantage of the benefits of remote astrophotography:
Practice and refine your processing skills with a wider variety of targets, conditions, and equipment.
Use higher-end equipment when you want to create an especially spectacular image.
Capture images from a different location or hemisphere.
If you’re crunched for time, take images without setting up the equipment.
If you have poor local sky or weather conditions, you can take images any time by choosing a location with better conditions since you are no longer limited to imaging only when local conditions are good.
What are the best options for remote astrophotography? A summary of the top providers including Insight Observatory, iTelescope, Telescope Live, and more.
Step-by-step guide: A walk-through using Insight Observatory’s ATEO-1 online 16″ f/3.7 astrograph reflector for astrophotography.
Whether you’re a beginner looking to learn the end-to-end process of capturing celestial images, or an experienced pro looking to hone your skills, remote astrophotography offers a great way to take your photography to the next level and expand your imaging possibilities.
About the author: Brian Taylor is a technology professional by day, amateur astronomer by night, and writes at TelescopeGuide. He loves exploring the wonder and beauty of the universe—and (especially) sharing it with others. The above article was adapted from its original, published at TelescopeGuide.
One of the Holy Grail quests for astrophotographers is the search for dark skies. Few of us are fortunate enough to live in ideal dark skies, but most of us are mobile enough to get to somewhere better than the center of an urban area.
In 2006, John Bortle published an article in Sky and Telescope describing an informal scale for rating your skies, now appropriately known as the Bortle scale. On his scale, 1 is best, 9 is worst. Bortle 9 is what I live under — I don’t bother with a flashlight when I go out in my backyard at midnight.
The contrast-enhanced shot above was taken after midnight with no moon in the sky. In person, only a couple of stars were visible when I took the shot. On the processed shot, I’ve circled the three bright stars of the prominent Summer Triangle. The other bright object on the left side of the image is Jupiter.
My local solution is a 100 mile (161 km) drive to my observatory at an elevation of 4,300 feet (1,310 meters), after which I’m under skies that are perhaps Bortle 4+ skies on a good night. The shot above was taken towards the southwest, where the glow of San Diego dominates the center horizon and the glow of the nearby town of Temecula and more distant Los Angeles begins on the right.
The cover photo (repeated above) was shot under first quarter moonlight in a site in San Pedro de Atacama at elevation 7,900 feet (2,407 meters) in northern Chile, which probably would be classified as a very good dark site (perhaps Bortle 1+). Despite a first quarter moon, the Milky Way is clearly visible. The volcanic peak in the background is Licancabur which is on the border between Chile and Bolivia. The top of the cone is 19,409 feet (5,916 meters).
Above is a mosaic shot at (by far) the darkest site I’ve ever visited (Namibia). It is situated on a high, dry plateau at the edge of the Kalahari desert with superb conditions for astrophotography, but is a real journey to reach. The image of the southern Milky Way is a 5-panel mosaic of 40-minute exposures on medium format film.
A more accessible site is Haleakala on the island of Maui. At an elevation of 10,023 feet (3,055 meters), the air is very transparent and steady, but as you can see in the image above, light pollution is clearly visible nearby. Tourism-oriented resorts and businesses outline the island shores on the left and right sides, with the central glow coming from the towns of Wailuku and Kahului, where the airport is located. On one hand, the top of the volcano is easily accessible by ordinary vehicles on a wide, paved road and is a national park. On the minus side, the peak is now so crowded that the National Park Service requires reservations to view the sunrise.
While perusing the light pollution maps may be helpful, it’s prudent to remember that like a map of the average cloudiness of the sky, these are averages. Like the actual weather, the local conditions at a particular location are highly dependent on several factors:
Brightness of lights in your immediate vicinity
Air pollution (atmospheric scattering)
The first point is the obvious one, which first comes to mind. Nearby lights can directly shine into your lens, causing reflection artifacts or affect your night vision. Seasonal effects include wind, fires, and fog. Holiday lighting is increasingly becoming a source of light pollution as cheap strings of LED lights are available.
A more subtle issue is the average glow of distant towns or cities, annoying especially for landscape astrophotographers. Even for deep sky photography, these distant light domes limit the direction and minimum altitude of shooting. Wide angle shots are particularly affected, with distinct gradients annoyingly spanning the photo. But even these effects vary. At my observatory, at certain times of the year, low coastal fog smothers the light domes of surrounding cities, improving the Bortle rating considerably.
The type of lighting also plays a significant role in the severity of light pollution effects. Many older types of lighting are in specific spectral bands, allowing at least the possibility of using filters to block some of the interference. Unfortunately, from the astronomers’ viewpoint, the ugly low-pressure sodium streetlight spectrum was the easiest to block, but it was such a monochromatic orange hue that it was hard to locate your car in a parking lot!
With the widespread availability of low-power LED lighting, many lights have been switched over to take advantage of the reliability and low-cost benefits. Unfortunately, to encourage the switch to LED lighting, manufacturers engineered bluer, more natural lighting, and in doing so, we have shot ourselves in the foot. LEDs are naturally very narrow-band sources of light, but phosphors have been added to absorb and re-emit the light to cover a wider spectrum. In doing so, we’ve managed to swing the light pollution spectrum towards the blue, which scatters in our atmosphere more than lighting with a redder color, as described in a recent study.
Air Pollution (Atmospheric Scattering)
The blue light scattering problem also raises the role played by particles in the air (whether considered pollution or not). The light sources, by themselves, would not be such a problem if the light did not have a way to scatter and bounce back at us. Smoke and urban smog are the most obvious contributors, but moisture and wind-whipped dust can also subtly affect contrast in our images, even though distinct layers of haze may not be obvious to the eye.
In the daytime, you can get an idea of how much of a problem scattering is for you by blocking the sun and seeing how blue the sky looks as you get close to the sun. Ideally, the sky will look dark blue right up to the edge of the sun. At night you can do the same test with the moon. At my observatory site, the sky can often look clear to the eye, but as soon as something bright like Venus or Jupiter rises, it becomes readily apparent that sky haze is present. In long exposures, large haloes (not related to chromatic aberration) become visible.
To get around this problem, a solution is to get higher in altitude to get above the low-lying air pollution as well as clouds. With thin and clear enough air, it’s possible to photograph the Milky Way even when the Moon (the worst natural light pollution source) is out. But even this may not be a good fix if a global event such as a large volcanic eruption has put ash high into the atmosphere. Your personal sensitivity to high altitudes may also limit this option.
The Simons Observatory (above) in northern Chile sits at 17,000 feet (5,182 meters), with air clear enough to see the Milky Way even with a first quarter moon in the sky.
Another often ignored source of light pollution concern is aircraft traffic. These cause a double-hit — light pollution as well as air pollution. Aircraft traffic exists at all hours of the day and night. At night, they are flying with bright navigation lights. A good strategy is to check not only light pollution maps, but also aircraft flight path maps, and choose a location appropriately.
In addition to the navigation lights of aircraft, engine exhaust is being emitted at high enough altitudes to linger for long periods, often in the form of visible contrails (high-altitude ice crystals).
What about satellites? For amateur astronomers, they are not a problem. They are much dimmer than aircraft, have no navigation beacons, and the low-flying ones are mostly visible near sunset or sunrise. For professional astronomers, they could become a problem, but amateur astronomers have larger problems to contend with.
Other Astronomers and Astrophotographers
And finally, I have to say that sometimes we are our own worst enemies. When we’re out shooting our own astrophotos, we need to keep in mind that 50 meters away, another astrophotographer may be trying to do his own thing. Lighting up the landscape with your flashlight may interfere with the next person’s shot. Your cellphone or camera rear screen may be as bad. Even the self-timer countdown flasher or memory card write light could be a problem, so have some black tape handy to suppress these sources of light.
As an astrophotographer, it’s also a good idea to avoid groups of amateur astronomers doing visual astronomy. They will often have groups of people with flashlights pointing everywhere, including directly at your camera. Green laser pointers are often a problem too and are bright enough to be picked up in photos (look closely at the image above) even when moved around. For this reason (as well as for eye safety), I strongly discourage the use of them as polar “finders” or pointers to targets.
Have you got a good location to recommend? Please add your comments below!
Astrophotography is by far one of the most specialized genres out there, requiring quite a bit of specific equipment, software, and technique, but capturing things that are unfathomable distances away can be really rewarding. If you are new to the genre or looking to improve your work, check out this awesome video tutorial that answers 10 of the most common questions people have about astrophotography.
Coming to you from Astro Backyard, this great video tutorial discusses 10 of the most common questions people have about astrophotography, ranging from the sort of equipment you should use to how to focus your camera and telescope. If you are really serious about astrophotography, it is well worth investing in an equatorial mount (it does not have to be a very expensive one to start). The problem is that due to the earth’s rotation relative to the stars, you can only shoot for so long before the stars start to blur due to the motion, and for deep sky objects, you need much longer total exposure times. An equatorial mount cancels out the earth’s rotation, keeping your camera still relative to the sky, thereby allowing you to shoot much longer exposures. Check out the video above for the full rundown.
Version 1.9 of Affinity Photo launched earlier this year in February and introduced an array of useful and powerful improvements, from linked layer functionality to better organisation for LUTs, OpenCL hardware acceleration for Windows and long-awaited saveable workspaces.
Introducing Astrophotography Stacking In Affinity
Flame And Horsehead Nebula HaRGB
One of the more esoteric additions was the introduction of a new ‘Persona’ (or workspace) for astrophotography stacking. This functionality is not commonly found in image editors – instead, it has always been the domain of dedicated astrophotography software, which can vary in price from free to several hundred dollars.
In this regard, Affinity Photo is relatively unique: it can perform the entire postproduction workflow required for professional-level astrophotography, all in 32-bit linear precision. The workflow is not complex either – if anything, the straightforward nature of the entire process may seem contradictory to expectations at first!
Astrophotography Stacking In An Inexpensive Photo Editor
Vela Supernova Remnant HaOIIIRGB
To understand the significance of having this functionality in a low-cost image editing application, we should consider the complexity of the stacking workflow and its requirements. We stack multiple exposures of the same subject to increase SNR (signal to noise ratio) – essentially, to reject noise and other artefacts from the final exposure, which allows you to pull through more meaningful detail of the actual night sky objects.
Depending on the subject and its brightness, long exposures – sometimes in excess of five or even ten minutes – are usually required to reveal enough detail, and with longer exposures comes increased noise levels and greater risk of visual artefacts like star trailing, light pollution and light trails from aircraft flying overhead. These all produce challenges during both the stacking and editing process that the software must be able to tackle.
There’s also the requirement of being able to calibrate the image frames before they are stacked together. This is achieved using a variety of calibration frames, which are often shot during the imaging session, although with temperature-controlled sensors and mounted telescope systems this is not always necessary.
The Stacking Process In Affinity Explained
Stack Persona (alpha)
The stacking process is easy in Affinity Photo: the light (image) frames and calibration frames are loaded into separate file lists within the Astrophotography Stack Persona, and you can configure various stacking options such as the clipping threshold, which is useful for rejecting aircraft light trails and other inconsistent pixel information. You then click the Stack button, and once the images have stacked you will see the final tone-stretched result. If you need to modify any settings, you can do so and click the Stack button again (with significantly reduced processing time) – each time you do this, a new layer will be placed into the Stacked Images panel at the bottom right.
Once you are happy with the result, you can click Apply and each stacked image is brought through as a layer into your main document’s layer stack. Levels and Curves adjustment layers are also provided by default which perform the initial tone stretching – you can tweak this further if required.
Stack Persona (White Fill)
For monochrome imaging, where narrowband or broadband filters are used to capture different wavelengths of light, you would typically stack each data set separately, then copy the final pixel layers into one document and blend them together. Layers may need to be aligned, which can be achieved by selecting them all and using Arrange>Align Layers by Stars.
From this point, it’s a fascinating editing process whose complexity can vary depending on the requirements of the subject. Light pollution can be tackled with the dedicated Remove Background filter, found in the Filters>Astrophotography menu. You can single-click to set sample points within the image and easily remove gradients from the background sky detail.
The software also has a comprehensive set of masking and selection options too, so you can easily make selections of star detail or background detail, then apply adjustments and live non-destructive filters. For example, you can use a Minimum Blur live filter to reduce the intensity of stars in the image or use an HSL adjustment to reduce background luminosity whilst boosting deep-sky object detail.
Since Affinity Photo also supports macros (recordable operations that can be played back instantly), you can speed up any techniques you find yourself using frequently, such as creating luminosity masks, applying your own tone stretching or even setting up blending of the initial monochrome data layers to produce the full-colour composition.
Another technical advantage to highlight is the ability to complete the entire workflow in 32-bit precision. With the exception of Median Blur (and therefore also Dust & Scratches), all adjustments, tools and filters are available for you to use in 32-bit. This cuts out the requirement of merging or flattening then converting to 16-bit in order to continue editing, and allows you to take advantage of processing entirely in a linear colour space from start to finish, as well as making use of the extra precision.
Orion Nebula HaOIII
Astrophotography, much like regular photography, can quickly become an expensive hobby or profession. Therefore, in some ways, you may argue that an extra few hundred dollars spent on dedicated astrophotography software is hardly worth quibbling over rather than investing a smaller amount into a more general image editing application. However, even if budget is not a concern, Affinity Photo offers a streamlined and straightforward workflow, especially if you are used to other layer-based image editing software. It’s ideal for newcomers to the genre, but also offers several notable advantages to seasoned astrophotographers as well, particularly for non-destructive workflows.
Even More Affinity Photo Astrophotography Tutorials
For anyone interested in exploring Affinity Photo’s astrophotography capabilities, we have a plethora of tutorial videos covering the subject available both on our website and YouTube.
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