Tag Archives: layering

Adding Special Touches to Your Astro Landscape

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

Blobulous Revisited – Part 1

It’s pretty amazing what you can accomplish with just a little bit of effort.  Below you’ll see a star trail formed using the Blobulous technique that I described in an earlier column on Advanced Star Trail Tricks.  There are many ways to achieve this effect. The method I described in the prior article – adding the last frame using Screen or Add blending – works especially well if the skies are dark. But here, I used high ISO shots about an hour before moonrise. Because of the high ISO exposures with a soon to rise moon the sky was blue not completely dark.  Adding the last frame to the stack as described earlier will work but it makes the Milky Way blow out and the sky overbright. I wanted the Milky Way to remain noticeable.


Selecting Images to Work With

There are few important things to note here. The radio telescope tracks the sky and slews from location to location causing blur. Each 20 second exposure was shot at ISO 3200, f/2.8 using a 15mm fish-eye lens on a Canon 5D Mark II. I carefully picked a range of images where the start of the sequence through to the end of the sequence included only images where the dish did not move “too far”. The next four frames show how dramatically the dish moved in subsequent shots. Had I included them it would have made quite a mess.


The dish moves far in 80 seconds…

To say it clearly: looking at the individual frames is what allowed me to zero in on the specific images I planned to stack. After selecting the range of images (C_072887 to C_072935),  I stacked them using good ‘ol brightness mode stacking. You can stack using a ton of methods but our favorite, of course, is to use the Advanced Stacker+ from StarCircleAcademy.com though the free TEST Stacker can do the job, as can a variety of free tools that we describe in this article and in our Star Trails Webinar.

To create the shot below on the RIGHT you’ll need Photoshop or some equally featured program that allows layering and masking like GIMP. Even the lowly, stunted Photoshop Elements will do the trick. After doing a normal brighten mode stack, the output looks like what you see on the left.  After some image manipulation magic, we achieve the result on the right.


Before (left) and After (right)


It would be tedious to show step by step what I did, so I will start with a “one shot” view. You’ll notice there are 9 layers that contribute to the final image.  The top – SLC-SCA – is obvious, it’s my watermark.

Results with all layers shown.

Results with all layers shown.

However you can also see the brighten mode stack (at the bottom), and a copy of that same stack with a layer mask.  If you look carefully it’s pretty obvious that the black on the mask corresponds to the upper part of the moving dish.  Sharp eyes will notice two additional blacked out parts corresponding to the other radio dishes.  Notice that above the stacked layer is a single frame: C_072934 – the next to last image from the set used in the stack. All the layers above the single frame are adjustments to correct color, white balance, hot pixels (the Heal layer), and to do some sharpening.


The single frame (934) is blended in Lighten mode with the stack. The stack is at 36% opacity.

The essential bit of magic here is that the Brighten layer is only used at 36% opacity. 36% was chosen by eye. I slowly reduced the opacity until the Milky Way became noticeable rather than a blur and yet the star trails remained noticeable.

The image was nearly complete by painting out (excluding) the blurred stack areas using a black brush at 100% opacity with a small amount of feathering – i.e. a brush that was not 100% hard.  It’s easy to paint on the mask and watch how the blurry dish from the stack is replaced by the non-blurry single image from C_072934.  If you’re wondering why I didn’t use the final image, C_072935, it’s because it was a tiny bit blurrier than the preceding image.

The rest of the adjustments are straight forward – they were all meant to fix contrast, darken the overbright areas and then correct for the color saturation increase that occurs when you darken an area with color.

We cover complete details in the PhotoManipulation webinar series.

Here is the image obtained from the next set of exposures after the dramatic dish move. This image used the “Streaks” stacking method available in the Advanced Stacker, but is otherwise identical in creation.


For yet one more take – using yet another Advanced Stacker Mode (long streaks), there is this.

Long Streak Runnin'

In the next column I’ll show all the steps I took to produce the first image on this page.


Bump up Those Stars

After publishing the article on the 600 Rule (and why it’s a lousy rule), I was heavily prodded by a reader who insisted that a 4, 5 or six pixel star streak is not noticeable and not to worry. My counter argument is: “it all depends!”  A larger print (greater magnification) will reveal the streak.  But that got me to thinking – and dangerous things happen when I start thinking.

How Do I Boost the Visibility of My Stars?

The obvious answer is to bump up the brightness and the contrast – but that creates other problems – including magnifying the noise. But there is a simple way to boost those stars – at a relatively low image quality cost.  And this method may very well remove some of the dash like appearance of a star in a longish exposure.

Are you ready? In Photoshop duplicate the layer. Select the duplicate layer. Activate the Move tool. Hold down the control (windows) or option (Mac) key and click the up (or down) arrow key exactly once. Photoshop calls this maneuver a “nudge”  Now change the blend mode to Lighten, 100%.

What do you get? Here is the original.



Now watch as we perform the “bump” (cursor over the image to see what was bumped)

Why Does this Trick Work?

Actually, your first question might be: why doesn’t my image get blurrier? The answer is that it does but you probably won’t notice even if you print the image LARGE. You can counteract blurry by masking off everything that is not sky in the nudged layer.  The reason that the stars seem to be brighter is that you’ve added more bright pixels in nearly the same location. The eye sees more light where every star is. If you look closely you may also notice that some other features get brighter too – the snag (dead tree) at the far right and the waterfall. To see the change in foreground details compare the Original with the Up One images.  Then compare the Up One with the Down One. In the Down One image I masked off any area that is not in the sky and as a result the tree and waterfall brightness do not change.

Perhaps you’re asking a different question like:

PS My thanks to Tiberiu Tesileanu whose questions and comments lead me to experiment with the “bump” strategy.

Advanced Star Trail Tricks

Published: Oct 11, 2012
Last Update: April 26, 2016

I have been playing with Star Trail processing for quite a while.  Ever since I wrote the StarCircleAcademy Stacking Action I’ve been tweaking processing to try different things. Sometimes failure is inevitable, sometimes… well, you’ll see.

First, you may want to look back through my earlier columns on shooting and processing star trails because this is not a primer on star trails – it builds on what I’ve previously written and this is not a good place to try to understand what stacking is.

Second, please understand that I use a variety of tools but almost all of my more successful endeavors end up as layers that are combined in Photoshop (CS5 at the moment).  You could combine your layers in GIMP if you don’t have Photoshop, but you’ll be out of luck if you try to use Lightroom.

Here are my star trail effects:

  1. Smoothee – Averaged sky and/or foreground to reduce the grittiness that sometimes results from brighten stacks. I’ve been espousing this for quite a while. See the Simple Astrophotography Processing Technique.
  2. Blobulous – stars at the beginning (or end) of a trail are made to stand out from the rest of the trail.
  3. Comets – star trails appear to grow brighter and the end of the trail looks like the nucleus of a comet.
  4. Streakers – Like comet only the trails are longer
  5. Blackened – A clever trick removes sky glow from light pollution, the moon, or twilight.

And of course you can make “Blobulous Comets” and “Blobulous Streakers” and “Blackened Smoothee Comets” and more.

Building Blocks

To creatively combine exposures, I usually create the following stacked frames.

  • Dark (Darken in Image Stacker/StarStax)
    The darkest elements emerge – especially the hot pixels
  • Brighten (aka lighten) stack
    The Brightest of everything is present, including hot pixel and more noticeable noise
  • Average
    Contrast is reduced, smoothness increased.
  • Additive (called “Stack” in Image Stacker)
    Hot pixels become really bright.
  • Scaled (called Stack/Average in Image Stacker)
    Allows some increase in brightness but more smoothness, too. Experiment with different divisors.

Normally I create all of these combinations using Image Stacker against my JPG files because it is really easy to do.  I end up with a set of frames something like these although I’ve significantly brightened them so that they are easier to see.


In a Nutshell: Combine the Average stack over the Brighten stack using Normal mode at 45% opacity.

I’ll start with the Smoothee technique since it’s probably the easiest to do and perhaps the easiest to understand.  The problem with “Brightness” (or lighten as it’s called in Photoshop) is that it will also pick up all the hot pixels, and the brightest bits of noise.  Averaging on the other hand tends to smooth out everything except for truly hot pixels since most noise is random. By putting an averaged stack as a layer over the brighten stack and then adjusting the blending modes and opacity you get a smoother sky and foreground.  Exactly what settings to use depend on the images, but surprisingly many of the blending modes for the Average layer work here including Darken, Multiply, Overlay, and Normal. The starting place for Opacity is about 45%.

Hint: You can also use an Additive stack instead of the average stack but usually only the Normal blend mode will work.  For even more fun combine the Additive stack and the Average stack.

For additional smoothness you can also subtract the “Darken Stack” while adjusting the opacity to prevent halos and weirdness.


In a Nutshell: Add one of the single frames more than once.

What do “Blobs” look like? Like this…

“Fat Star” processing.

There are two ways to produce “Blobs”. One way is to add “Comets” to a smoothed star trail. The other is to simply pick an image (usually the last one in the set) and add it in using “Add” or “Screen” mode. To make the blob more pronounced duplicate the last frame so it’s added twice. BUT remember when you add in any single image the hot pixels are going to come out… and even more so if you add an image twice.

Comets and Streakers

These two techniques require some fancy stacking techniques. Fortunately I’ve created an action to do all the fancy stuff.  I’ll be rolling out the action and the explanation to my Photo Manipulation Webinar participants first <NOTE: The Advanced Stacker PLUS action has been released and is available for purchase in our store>.

Oh, here is a peak at what the Comet action looks like:

What's The Point?

And here is what an animation of comets might look like:



I know you’re going to ask so let me save you some typing. Except for the “Comet” image above, all images used in these illustrations were taken during the Ancient Bristlecone Pine Workshop in the Patriarch Grove on White Mountain, East of Bishop, California.

The 34 or so images that I’ve combined in the examples above were all taken with the following settings: Canon 50D, ISO 400, f/3.5, 79 seconds, 10-22mm lens at 15mm.