Category Archives: Astrophotography

Aurora: The Bewitching Glow

First published 06-Jan-2024. Last revised 07-Jan-2024

Who doesn’t want a photo of a curvaceous near-earth phenomenon called an Aurora? Not you? Well if not, you need not read on. But if you’re thinking that sounds interesting then you’ve found a good place to hone up on aurora and aurora photography. We’ll address what aurora are, how to plan for them, equipment, and photography methods including how to get decent photos from night capable cameras and typical current generation cell phones. In many ways aurora photography is similar to trying to catch meteors – see: Coaxing a Meteor into Smiling for your Camera – only aurora are easier!

Until recently, photo 3, below was the only aurora photo I was ever able to capture, and it was in 2011 while travelling back by plane from the Royal Observatory in London where I had won Astronomy Photographer of the Year, 2010. While flying over Canada, I noticed an odd glow that seemed to be moving unexpectedly. Suspecting it might be an aurora borealis, I covered the window up as best I could with a dark coat while simultaneously holding my camera against the window for a 4 second exposure on a bumpy flight. The camera immediately registered the tell-tale green color which wasn’t visible to my eye.

Photo 3: Window Seat Aurora Borealis

What IS an Aurora? and What Does it Look like “In Person”?

An aurora (which is named after the Roman goddess of Dawn) occurs when the sun ejects charged particles toward the earth. Those charged particles are warped by our earth’s magnetosphere which concentrates them like a lens and they then collide with components of our atmosphere (in the ionosphere and thermosphere) as high up as 1000 miles to as low as 30 miles above the earth. Note that the magnetosphere is centered around the earth’s magnetic poles, not the geographic poles. The north magnetic pole continuously moves and is presently near 81°18′N 110°48′W which is Ellsmere Island, Canada NOT at the geographic north pole (90°N). The location of the north magnetic pole within the North American continent is fortuitous for those of us who live in the extreme northern United States especially for those in Alaska, and Canada. Though the band of possible aurora sighting locations is broad and includes other northern countries and continents it favors Northern North America. Aurorae (the plural of Aurora) that occur in the Northern hemisphere are called Aurora Borealis from Boreas, the Greek god of the north wind. Those in the Southern hemisphere are named after the Greek god of the southern wind: Auster and are called Aurora Australis.

Other interesting places in the world to see the Aurora Borealis include the northern areas of Norway, Sweden, Lapland, Iceland, Greenland and Finland as well as the Siberian region of Russia. In the south, Aurora can sometimes be seen in New Zealand, the Southern tip of Chile (e.g. Tierra del Fuego) or the Falklands. In the south, however the best place would be on the continent of Antarctica.

All you really need to see an aurora is a reasonably dark sky and sufficient solar wind to produce a strong aurora. Aurora have no seasonality. The anticipated strength (brightness) of the aurora is forecast by the “Kp Index“. Unlike the apparent magnitude scale used by astronomers in which the smaller the number the brighter the object, the Kp scale goes from 1 to 9 with 9 being the brightest and MOST likely to produce aurora. During our sojourn in the Fairbanks area, the scale ran from 2 Kp to 5 Kp – and as I note below that 5 Kp event on December 17th was awe inspiring.

But what does an aurora look like in person?

Blurry cellphone photo of an Aurora:
f/1.8, ISO-3200, 4 sec
Photo 4: Aurora as it might appear to the eye. (Taken with a cell phone)

Most aurora will appear gray to the human eye which is poor at discerning color in dim light. A camera can capture the true color, and that color is generally predominately green due to the interaction of the charged particles with oxygen in the atmosphere. In Photo 4 you can see a peculiar diagonal glow that IS a diffuse aurora partially obscured by clouds and it is close to what it looked like to the naked eye – though the whole scene was dimmer in person.

What an aurora actually looks like depends on the overall sky darkness, the cloud cover, and the strength of the aurora. Just as seeing the true majesty of the Milky Way requires dark skies, the beauty and shape of the aurora is easier to spot in dark skies. A dim aurora might look exactly like the amorphous cloud in photo 4, above. In fact, many people who first notice aurora think they ARE clouds illuminated by moonlight or some distant city lights. A stronger, brighter aurora might have discernable hints of green, red or blue. And the aurora may also move quickly and chaotically about the sky in a display that can only be described as mesmerizing, and evocative. We got very lucky. Of the 4 nights we spent seeking the aurora we saw aurora on 3 of those nights, and the fourth night literally had this author in tears over the sheer beauty of what he saw. Don’t let this meager photo dissuade you… we’ll discuss in a bit how to get much better photos and show you much more delicious examples. We were fortunate in that there were two very large solar flares (class X) that occurred on December 14th

But here is a timelapse from the most energetic of the nights we watched. It zips along at about 15 times the actual speed.

Dance of the Northern Sky: December 17, 2023


Where can you See an Aurora? and WHEN?

Photo 5: Samsung cellphone Capture of Aurora at Borealis Basecamp, Fairbanks, Alaska

The short answer to the question is literally ANYWHERE with great good luck, but the the more accurate answer is near (about 20 degrees from) the north or south magnetic poles when the sky is dark and there is significant solar activity. The sun goes through an 11-year cycle from a quiet period (solar minimum) to lots of sunspots (solar maximum) and back to a quiet period. The sunspots are generally where the charged particles come from Coronal Mass Ejections (CMEs). The next solar maximum is in 2024 and the previous maximum was 2013 but the years on either side of the maximum can be just as good as the year of the maximum -> so now you know why we went in 2023!

A more detailed explanation of WHERE includes these criteria:

  1. A place with non light-polluted skies
  2. near the arctic or antarctic magnetic poles but preferably not at the poles. The farther you are away from the magnetic poles, the less likely you are to see any aurora activity
  3. generally favorable weather (meaning at least some clear skies).
  4. a season when there is true night/darkness. For example August in Alaska would be a bad choice because it never gets truly dark – which is why it’s called the “Land of the Midnight Sun”. In late December through January Fairbanks and farther north could aptly be called the “Land of Perpetual Midnight”. The more dark, the better the chances!
  5. travel distance and cost,
  6. availability and cost of lodging,
  7. and if you’re looking for that primo shot, consideration of the foreground for your shot (a flat field may not be as compelling as a snow flocked forest with a mountain poking out in the distance).
  8. time on site. Aurora are a “Space Weather” phenomenon and that is apt in the sense that you might confidently book a one-night stay in Seattle, Washington and expect it to rain because it frequently does so, but the longer you stay at a site, the more likely you are to observe the Space Weather you’re interested in and hopefully the less likely that the snow, rain, clouds or fog are to completely blot out your aurora experience. The first night we were on site at Borealis Basecamp it had snowed all day and was a gloomy overcast, foreboding night. We thought it would be a bust and we could catch up on sleep, but at 2:00 AM it cleared enough that the Aurora was pretty awesome.
Photo 6: The first night after heavy cloud cover an aurora broke out. Orion is at the right, Gemini in the middle

One strategy is to book a place and hope that while you’re there you get an aurora. I call this tactic “Book and Hope“. But there is another tactic you can try, too.

Monitor and Go

Another approach is to pick where to go based on monitoring the Space Weather reports for strong solar events and correlating the aurora predictions with weather forecasts. You can immediately arrange travel to an accessible location in the US or Canada at the last minute since there are often 2 to 3 days between the observed solar activity (CMEs) and the increase in aurora activity. The Monitor and Go approach may cost more and require more flexibility. You may find that some of the best locations and tours are booked seasons in advance for those who took the book and hope approach. We are strong proponents of Having a Plan C – which means having alternatives pre-investigated in advance of any possible opportunity to see the aurora.

If not above latitude 45 or so the aurora will be low in the northern horizon. But the closer you get to the magnetic pole, the higher in the sky the phenomenon will occur. In fact, one driver in Fairbanks told me “we don’t call them the Northern Lights here we just call them The LIGHTS because for us they are usually overhead and seldom only in the north.”

If you don’t live in Alaska or Canada, but are lucky enough to live in the northern-most portions of the northern US the chances of seeing an aurora are pretty good on as many as 5 or 6 nights a year when there is significant space weather (Kp index forecast is greater than 5). It may just be a matter of figuring out what nearby location has the darkest skies toward the north. Some of my photo buddies in New England, Washington, and Idaho have managed several times through a year to get captures of an aurora when the activity level is high. See the Viewing the Aurora link, in the resource list below for a better understanding of Kp.

Aurora from New England captured by Brian Drourr
Brian Drourr captured this image near his home in Burlington, VT (used by permission) Click the image to visit Brian’s Facebook page. https://www.facebook.com/brian.drourr

Where Did StarCircleAcademy Go?

For nearly all the reasons cited above, we chose to go during the winter to the area near Fairbanks, Alaska, and specifically to Borealis Basecamp which is located about 20 miles north of Fairbanks. We chose December for it’s longer nights and snowy environment (better for interesting foregrounds) even though December in Fairbanks has more cloud cover than say March. We’ll describe more about Borealis Basecamp in the next article, including features of the “igloo” accommodations offered, as well as weather considerations.

Gray, overcast skies at the Borealis Basecamp north of Fairbanks, Alaska, with a cheeky self portrait and a not-live  Grizzly bear.
Photo 7: Borealis Basecamp accommodations. The grizzly bear wasn’t really there 🙂 This was created by combining a panorama with a photo from the Fairbanks Airport all in the Samsung cell phone. The panorama makes the igloo appear squashed (smaller) than it actually is. The model inside is the author’s wife.
Photo 8: The author in a Borealis Basecamp “Igloo” in pre-dawn hours with stars and multi-colored Aurora visible.

There is a downside to Fairbanks, Alaska. By going in Winter… there are only 4 or 5 hours of daylight, and the average high temperature hovers near zero Farenheit (-17 Celsius). Borealis Basecamp is 800 feet higher in altitude than Fairbanks, so is usually a few degrees warmer (cold air sinks and settles in low areas). Borealis Basecamp is situated north of Fairbanks which helps because the light pollution from Fairbanks only affects the southern skies. There are other areas worth considering in the vicinity of Fairbanks as well, like Chena Hot Springs, Chatanika Lodge, Aurora Borealis Lodge north east of Fox, and many more. You can also opt to stay in Fairbanks and charter expeditions that ferry you by van to the best available spots for photography. Or if you are accustomed to driving on ice and snow you can be brave and rent a car. Beware that locals don’t call them “roundabouts” they call them “slide-abouts”. The upside to residing in Fairbanks is that you can avail yourself of the variety of restaurants and amenities in Fairbanks and also get aurora photos. The disadvantage is that the aurora can pop up at any time so generally you’d want to be out from say 10 pm until 3 am to have a good chance of catching what does occur. In our case at the Borealis Basecamp (as is true at nearly ALL aurora oriented accommodations), they notified us by phone when an aurora was visible and it was a matter of looking through the windows to decide if it was worth donning all the layers of clothing and heading out of doors or just staying in bed and observing in comfort. Plus we had the advantage of retreating indoors for breaks or to rewarm as needed. Indeed, one morning the aurora display was dim but really awesome at 8 am!

Photo 9: Multicolor Aurora at Basecamp Igloo 301 – Glow from on site restaurant.

Resources and Links


Parts 2 and 3 of this Series:

2 Aurora Photography with A Night Capable Camera
   + What is a “Night capable” camera?
   + Equipment (Camera, Tripod, warmers, dew heaters, …) 
   + Aurora aspects that dictate settings.
   + Adapting to conditions – both of the Aurora and the weather.
+ What to pay attention to to get the best results (there are 3 keys!)
   + Batteries, camera controls and tripods.
   + Aurora photography goals and considerations for getting a better picture.
+ Preparing for Winter in Alaska
+ Is -20 F survivable? (Short answer, yes!)
+ What should I bring / how should I dress?
+ What is Borealis Basecamp like?
+ Tips from Borealis Basecamp staff.

3. Aurora and Night Photography with a Cell Phone COMING SOON
   + Cellphone cameras – are they usable for aurora photos?
+ Stablizing a cell phone for better photos (both hardware and posture!)
   + iPhone settings – “Night” and “Pro” mode
   + Android phone settings “Night” and “Pro” mode
   + Handheld or stabilized? 
+ How to hold a cellphone if you DO NOT have a tripod/stable base
   + Hands free photos (e.g. tripod plus voice command or bluetooth trigger)

Stacking: the Overloaded Word That Needs Explanation

The current rage of “stacked Milky Way” (or night sky) captures is quite different from the star trail or timestacks style of captures. Huh? The words stack and stacking are overloaded with many different meanings. Let’s see if we can add some precision and clarification.

Here are some of the variations possible:

  • Auto Blend Layers with Stacking: Used for macro/focus stacking, HDR, and generic image blending – NOT for astro images!
  • Lighten Mode Stacking: Creating Star Trails!
  • Statistics Mode Blending (Stacking): Can perform the same operation as Lighten Mode Stacking when the option “Maximum” is used, however Statistics are heavy weight and more complicated to do in our opinion.
  • Align and Stack: Deep sky astrophotography using several images taken one after another as quickly as possible. Photoshop doesn’t do this well, but we describe how in the next section. Align is the distinguishing word here.
  • Tracked Stacked Images: For still astrophotography images with less noise and greater detail. A device is required that tracks the sky rotation – the word tracked is the key here.

    Adobe Lightroom and Adobe Bridge “Stacking”

  • Group into Stack:  Not stacking at all! It really just means “create a group”.

The above is NOT an exhaustive list of the kinds of stacking you may hear about!

Stacking Types Explained

Group into Stack

Let’s start with the easy one: Stacking may mean add to group. In Lightroom and Adobe Bridge you can pick several photos and the options  Stacking -> Group into Stack. Or pick several photos and either Photo Merge to HDR or Panorama with the “Create Stack” option checked. In this context, Stacking and Stack just means group.  Unfortunately a photo can only appear in one stack, and you cannot stack photos from different folders together.

Why would you want a photo to appear in two (or more) stacks groups? Here is an example where I used a single top shot and created two different panoramas.

Panoramas 1 and 2 were both created using image 3 (608095.NEF) but when panorama 2 was created, image 3 was removed from the stack (group) for 1 and added to the stack (group) with 2. Furthermore, you can see that the panorama and the two photos used to create it were all added into the group (notice the last image says 3 of 3).

Blend Layers using Lighten Mode

Stacking may mean blend photos in lighten or darken blend mode – examples are star trails and timestacks. In this usage, the lightest (or darkest) of all the pixels in each image is selected. This is the kind of stacking that AdvancedStacker Plus does. Below is an example of taking several images that we collected over time with long delays between each exposure causing the “dotted” appearance of the star trail.

Several layers of images taken at intervals all set to blend mode “Lighten”

Align and Blend Stacking

Stacking can ALSO mean ALIGN and blend images with median, mean (aka average) or more sophisticated algorithms. Indeed astroimagers have been doing this style of blending for years using techniques that involve “star registration” (aligning stars with stars) and some pretty fancy stacking algorithms like Alpha-Kappa Median Clipping and Entropy Weighted Average. The key point here is the alignment. Indeed, here at StarCircleAcademy, we’ve explained how you can brighten and reduce noise in your foreground using simple astrophotography processing techniques.  See below for how to accomplish Align and Blend Stacking in Photoshop, and plenty of warnings about why this method is very likely to FAIL using Photoshop as the tool.

You may also see references to tracked, stacked images. These are the same as “align and blend” just described, except that to capture the image, the camera is guided by an external device (or by some fancy internal hardware), to allow longer exposures of the stars without getting unintentional trailing (smears) of stars.

The takeaway is that not all stacking is created equal. You need to know the context to understand what is meant by the word: stacking.

Focus Stacking / Auto Blend Layers

In Photoshop there is Edit -> Auto-Blend Layers -> Stack Images this is yet another kind of stacking (focus stacking) and despite the wording is NOT the kind of operation needed to ALIGN and Blend astro images. If you don’t believe us, give it a try and you’ll see it will do very weird things with your layers. Below are the same images as earlier. Note the bizarre masks it created to do the blending.

Edit -> Auto-Blend Layers -> Stack Images makes a mess. We told you so! Click to see a bigger image.


Aligned, Stacked Starry Landscape Images

While it would probably be better to make this a separate article in itself, we found it painful enough that we don’t recommend bothering – and yet we proceed to explain HOW to do it anyway!

If you want the cleanest possible images, you’ll – of course – want to reduce the overall noise  and bring out details by using many images instead of one. This approach is not all puppies and kittens. Here are some of the pitfalls:

  1. The direction of sky movement relative to the ground has a significant influence on the quality of the result (as well as the order chosen for alignment). In general, setting constellations are better than rising ones.
  2. Most of the existing tutorials will assume that you have a recent (CC) version of Photoshop with statistics and an an “Auto Align” that properly manages masked regions.
  3. Some of the tutorials we’ve observed are more cumbersome than they need be. There are plenty of hotkeys and mouse shortcuts to make the process go pretty quickly.
  4. More than 10 or so images can become quite demanding on machine resources.
  5. The complexity of your foreground will also affect the outcome. A clean, crisp separation between sky and land is preferable. Trees, poles, wires, and other things that extend through the sky are problematic.
  6. Lens distortion can also adversely affect the outcome.

Aligned Stacking Procedure

  1. Load all the photos as layers in Photoshop.
  2. Heal out airplane and satellite trails from each layer.
  3. Select all the layers and add to a group named “Sky
  4. Right click the Sky Group and duplicate the whole group as “Foreground”
  5. Select all the layers in Foreground.  Use Layer -> Smart Object -> Convert to Smart Object.
  6. Select Layer -> Smart Object -> Stack Mode -> Mean
  7. Duplicate Mean using Ctl-Alt-Shift-E (Command-Option-Shift-E on MAC). Label the newly created layer “Mean” and turn it off.
  8. Select all layers in Sky. Set blend mode to “Lighten” and observe the direction of star movement against the ground.
  9. Be sure the image with stars nearest the ground is at the BOTTOM of the stack. The bottom layer will be your base for alignment. You can drag layers around, or Layer -> Arrange -> Reverse may do the trick.
  10. Create a mask keeping as much of the sky as is easy to do but that DOESN’T include any ground  or fixed location objects. IMPORTANT: Be sure the mask doesn’t have holes in it, including at the bottom corners. Click the layer mask, hold down the Alt (Option) key and drag the mask to the next sky layer. Repeat until all sky images are masked with the same mask.
  11. Select the bottom layer and lock it  (Layers -> Lock Layers -> check Position -> Ok)
  12. Select all the sky layers.
  13. Chose Edit -> Auto Align Layers -> Auto
  14. When alignment is done, set blend mode for all sky layers to Darken. If stars are disappearing in the result image, that’s bad.
    1. If alignment is great everywhere, that is you have plenty of stars, you’re done. But it probably won’t be. So…
    2. Duplicate the current layers to a NEW document – call it whatever you want, but perhaps “Left looks good” makes sense.
    3. Open the history palette and click just above the “Align Layers” item (to restore to before the alignment was done). Lock the TOP layer (see item 11) and repeat steps 12-14.
    4. If a large portion of the image still has streaks in some quadrant, try undoing align, undoing the lock and re-aligning.
    5. If you’re still getting a significant amount of streaking you can also try Auto Align -> Reposition rather than auto.

      Q: Why do I have disappearing stars?
      A: The reason they are disappearing is because they are not aligned. In Darken mode, the darker sky “wins” out over the several stars. This COULD be a good thing in other situations, but not here!

      Q: If I went through the trouble of doing all this alignment, why is it still “off”?
      A: Photoshop isn’t optimized to align stars. Secondly, lens distortion makes a star move non-uniformly across the sensor. And third: stars at different declinations (celestial latitudes) travel at different speeds across the field. To eliminate streaks, the best solution is to track the sky.


  15. Take the aligned sky, delete all the layer masks. With all the aligned sky layers selected, create a smart Object.
  16. Do the same Stack Mode “Mean” trick for the sky smart object that you previously did for the foreground.
  17. The rest is pretty straight forward. Turn the foreground (mean) back on. Use a selection to reveal only the foreground and apply that to the Foreground Group.
  18. Adjust contrast, color balance, vibrance, etc. to your satisfaction.
  19. Save the kit and caboodle.

Does all this seem too complicated? Well, then perhaps you might consider using these tools instead. They do most of the hard work for you and they KNOW the difference between stars and foreground (usually because you help them know).

  • On a Mac: Starry Landscape Stacker – from the Mac App Store
  • On a PC: Sequator – do a Google Search to download it.

By the way there are many astro processing tools, like Deep Sky Stacker – but most/all of them expect that your images will have NO foreground or non-moving objects like wires in them.

Landscape Astrophotography

Thanks for attending my Landscape Astrophotography discourse with the San Jose Astronomical Association on Tuesday, June 19, 2018. 7:30 PM to 10:00 PM. Most of the audience are Astrophotographers.

Below is a form you can fill out and we will email you a PDF of the notes from this lecture.  Following are some brief excerpts from the talk.

The Meeting of Earth and Sky

Big Sur, California, has earned a reputation for being The Greatest Meeting of Land & Sea, a phrase attributed to Robinson Jeffers, the “Walt Whitman” of the West Coast. Indeed living here is inspiring. The towering cliffs and mountains, lush forests, crashing, craggy Pacific surf all work together to evoke a sense of beauty and wonder that is astonishingly intimate.  There are certainly other beautiful places in the world – even nearby. But I believe that there is awesome, virtually undiscovered beauty that touches nearly everywhere in the world: the night sky.

Night Sky photography has grown by leaps and bounds in the last decades. Prior to the age of digital photography, there were relatively few painters of the night sky. Not surprisingly, none of those painters painted just stars. All featured stars with landscapes. Perhaps the most well-known painter of the night is Vincent Van Gogh. In Van Gogh’s day, light pollution was far, far less noxious than it is now. Indeed our super abundance of artificial light has rendered our night sky almost unobservable. But the night sky has such depth and mystery that everyone should find a dark sky to sit under for a time. Part of the allure of the night sky is its expansiveness… its immense scale.

Because the scale of the night sky is difficult to grasp I believe it is important to link human-scale to the starry night. Deep-sky photography of nebula and galaxies reveals things completely unseen or unseeable by the naked eye – and the revelation of those objects is  compelling and engaging. But even more compelling are photographs that tie humanly identifiable scale to the mysterious night.

In addition to scale, compelling photographs reveal the unexpected. Photographs can show time, location, relationships, colors, and details that are unobservable by looking. To draw lay people, however, I believe there must be a strong link between what is observable with what is not: a Marriage of Earth and Sky. And for that reason, I’m urging Astrophotographers and astronomers to try Landscape Astrophotography.

As Numerous as the Grains of Sand

This is truly a meeting of Land, Sea and Sky

For more details, please see the accompanying notes.



Landscape Astrophotography Notes
Landscape Astrophotography Notes
71+ Pages of notes covering the following topics:
  1. How to Make Images Memorable
    • Scale / Grandeur
    • Connectedness
    • Interest
    • Revelation
  2. Impact of Photos
  3. How to Create Scale / Grandeur
  4. How to Connect - Interest and Familiarity
  5. Revelatory Photographs
    • Time | Location | Relationships | Familiarity | Seeing Differently | Surprising Colors | Intricate Detail
  6. Inspiration from Painting
  7. A sense of place
  8. An Astrophotography Idea
  9. Conclusion
  10. Resources and References

 

Other articles on this site that you may find relevant include:

Adding Special Touches to Your Astro Landscape

Published: November 6, 2107

1000 ISO, f/2, 3 minute exposure with some augmented stars

Because stars are pinpoints of light, the camera does not capture them as our eyes see them. To our eyes, brighter stars stand out more noticeably than dimmer ones. At a workshop in Alabama Hills, one of the participants, Julian Köpke, was using a diffusion filter so the stars captured would look more like you see with the naked eye. Sometimes nature provides its own diffusion filter in the form of high, thin cirrus clouds as shown below. The large bright orb is the star Sirius in the constellation Canus Major (Big Dog). The orange star near the top of the frame is Betelgeuse in the constellation Orion. One nice thing about the blur that the clouds added is the star color is more noticeable. But the diffusion here is not uniform because the belt stars (Alnitak, Alnilam and Mintaka) and “corner” stars (Bellatrix, Rigel, Saiph) in Orion are all noticeably brighter than the surrounding stars while in this photo only Betelgeuse and Rigel stand out.

Dog Star [C_065586]

You can create a make-shift diffusion filter by shooting through a nylon stocking – or buy a diffusion filter. The disadvantages of using a filter are that everything is blurred – including the foreground and you reduce the amount of light collected. Most night sky photographers try to avoid clouds and you will get an image like this:

The moon and Teapot Asterism in Sagittarius – over Lone Pine Peak – as shot.

When what you had in mind is something like this:

Same Photo as above, but with the Teapot Asterism in Sagittarius enhanced.

How to Bring Out Star Color And Enhance The Apparent Star Size

Our Advanced Stacker Plus has two built-in ways to increase star brightness. We call those Bump Up and Pump Up the stars. Bump Up creates a small blur by literally duplicating the shot , nudging the duplicate(s) and recombining .  Pump Up is more sophisticated and tries to find the stars so it can then apply enhancements to just the stars. But there is a new tool in the arsenal that I have begun using: Star Spikes Pro from ProDigital Software.  Version 4 is the latest as of this writing.

NOTE: Star Spikes Pro and HLVG described later are currently only available on Windows machines.

You can use the Star Spikes Pro plugin to add diffraction spikes and diffusion. The most common diffraction spikes you see with stars are due to obstructions in the telescope used to photograph them and many people come to think of the spikes as evidence of astrophotography.  You can create diffraction spikes easily on your own.- just stop down your aperture;  however stopping down to make stars create those spikes will not work well.

The first time I tried to use Star Spikes Pro it did not quite work as I expected.

Look hard. Star Spikes Pro decided the moon was a huge star outclassing all others.

Indeed it took me a bit to realize what was going on. The good news is it was easy to work around. The huge moon looks like a huge star to Star Spikes Pro – and that makes perfect sense since the plugin is usually used with Astrophotography that does not involve landscapes.

Here is how I made it work as I wanted and limited the effect to just the desired stars.

Layer Palette and Steps to Enhance The Teapot Asterism

Above left is the layer palette. Look carefully and you may spot the fix. After loading the image (1) I first duplicated the original and called the new layer Heal (2). I then did minor contrast adjustments, used the healing brush to remove hot pixels and other offenses (short satellite trail). Next I duplicated the Heal to another layer (3) and fed it into Hasta La Vista Green – a free plugin written by Rogelio Bernal Andreo of DeepSkyColors. HLVG removes green which is an unnatural sky color usually caused by RGB artifacts. HLVG operates on the entire layer and does not know the difference between land and sky. To leave the natural green in my landscape I used the quick selection tool, dragged it across the sky followed by Select -> Modify -> Expand 4 pixels. Then I created a Layer Mask using “Reveal Selection” (4). That made the foreground come back to its normal state. If you look carefully you will notice I also used a white brush to add some of that green removal back onto the mountain by painting on the HLVG layer mask (4).

The next operation was a finger twisting sequence that has no menu equivalent: Ctrl-Alt-Shift-E (on Mac that’s Command-Option-Shift-E). What that sequence does is “flatten” all the visible layers and create a NEW layer in the process (5). That layer I called Input to SSP.  Since I had discovered that Star Spikes Pro was confused by the moon (and could be confused by the foreground), I used the quick selection tool again and brushed it across the foreground. By default using the quick select tool again ADDs to the current selection so I brushed it around inside the moon and its halo. At this point I did not need to create another layer (Ctrl-J/Command-J or Duplicate Layer) but I did so that it was easy to see what happens next. After creating the new layer I selected it and used the delete key. Delete removes the selection making it transparent – that is the foreground and moon were now gone (6).

Next up: let Star Spikes Pro loose on the image. First deselect (Ctrl-D Command-D) or Select -> Deselect), and feed the sky layer to Star Spikes Pro via Filter -> ProDigital Software -> Star Spikes Pro.  The defaults for SSP produced the image below (I’ve zoomed in on the teapot asterism)

I felt the color was a bit too strong, and I did not want the diffraction spikes. The next step was to select “Advanced” – just below Settings, set the Primary quantity to zero. Next was the Secondary tab where I reduced the quantity to 44, the intensity I bumped up to 23. Soft flare I set quantity to 12, bumped up the intensity, dialed down the size a little and dialed down the Hue to -21. These adjustments were all based on eyeballing the image and were made for aesthetic appeal.  After all the adjustments looked about right, I saved the settings as a new adjustment I called “DiffusionOnly”. Finally I clicked OK and my layer was all nicely done by the SSP filter.

The filter processed a few more stars than I intended to augment. The simple solution was to create a “Reveal All Layer Mask”, select a brush, the color black and paint out all the effects I did not want on the layer mask (7).

The final operation was to use an Adjustment Layer (8) to increase the contrast and restrict that adjustment to the sky (where you see white) and tone the adjustment down a little with a low-flow back brush on one area that looked a little too dark.

The topmost layer in the layer palette is my watermark.

There Is An Easier Way!

With some experimentation, and some coaching from the plugin author I discovered that Star Spikes Pro has several features that make the process easier than I imagined. Instead of creating the transparency (deleting the moon and landscape) I only needed to select the area I wanted Star Spikes Pro to operate on.

Also, instead of masking off the stars I did not want affected after the fact, Star Spikes Pro has two tools to greatly simplify things the: “Hide” tool to turn off any effect that I did not want, and the “Show” tool to turn the effect on.

 

Star Spikes Pro limited to specific section of the sky via a selection and using the Hide tool to turn off an effect.

 

The net is that you can get that nice diffusion effect for your stars without having to compromise by shooting through a diffusion filter. However if you DO want to try a diffusion filter, I recommend you take two shots quickly. One with the filter off, one with the filter on. You can then place the diffused shot over the normal shot. Set the diffused shot to Lighten and mask in (or out) the areas where you want the diffusion to show through.

If you’re wondering whether there is a way to get the diffusion effect on a Mac or without purchasing Star Spikes Pro, there is, but it requires a lot of Photoshop twiddling and it is not anywhere near as pleasant as using ProDigital Software’s Star Spikes Pro.

Disclaimer and Book

I am not affiliated with ProDigital Sofware. I am a happy customer of Star Spikes Pro (and another product called Astronomy Tools). I was not paid, or encouraged to write about the product. I chose to because it is that good. Rogelio Bernal Andreo  author of Hasta La Vista Green and purveyor of DeepSkyColors is a friend and a multi-multi award-winning astrophotographer. He has a Kickstarter Project that I recommend you look into called Notes From the Stars

Notes from The Stars: 10 Award Winning Authors