Geminid Meteor (and other) Shower Tips

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Psst. It’s not a secret but we love meteor showers here at StarCircleAcademy.com. So much so, that we frequently schedule expeditions to capture meteors in interesting dark sky locations.  The latest expedition is in a few days. But if you look through our catalog of events, (e.g. the latest and this one) you’ll see we’ve been hunting meteors for quite a long time.

Star Man and Perseus [C_059960-1]

The things you want to happen for a meteor shower include a non-intervening moon. Showers peaking on or near full moons are usually disappointing. Then, of course you’ll will want good weather, and an interesting foreground.  However there is no cookie-cutter approach to getting that to all work out.  For the Geminid meteor shower, it’s useful to know that Gemini rises in the East a little after sunset and sets in the west around sunrise. If you want to get the MOST meteors, you generally want to shoot after midnight and before dawn (so southwest), and thus southwest is the direction you’ll want the darkest skies. But if spending midnight to dawn somewhere is not practical for you, consider finding dark skies facing the south East instead.

Meteors CAN appear anywhere in the sky, however, so even when we suggest dark skies to the south, do not let that stop you from finding dark skies in any direction.  The interesting foreground you want may only work with a Northern view.

We describe at length how to find dark skies in this article and in the discussion consider alternatives, such as  distance, weather, and goals. In that article we also link to a resource to help you find dark skies. But do not be mislead: not all dark skies are created equal and there is really no substitute for having been in a location a time or two to know how “dark” is “dark.” Understand that weather conditions significantly affect the darkness of skies. Dry, arid places as a rule will be darker than moister climes.

Once you have landed on a place, you need to know how to shoot those meteors – so we have an article for that, too!  And once you get those little streakers, you will want to be confident that they really ARE meteors (most of the time they are not). So if you want to know that what you got are indeed meteors, please read our article on identifying those streaks accurately.

Satellite Flash (Iridium) [5_033852-4br]

 

To fully enjoy a meteor shower we suggest the following preparations:

  1. Dress appropriately. Assume it will be 20 degrees F colder than the stated overnight low. Not because it will be colder, but because with no sun to warm you at all plus little activity it will FEEL colder.
  2. Bring a fully reclining chair or sleeping mat so you can lay down and look straight up (or toward the darkest skies).
  3. Bring a blanket or sleeping bag and a pillow.
  4. Bring some hot (and/or cold) beverages in a thermos and some snacks.
  5. Set up you camera with an equatorial mount to track the skies, or just point it toward the dark. Use an intervalometer to automatically take photos (using the settings we suggested in this article – don’t want to read that: try ISO 6400, maximum aperture, 20 seconds or less).
  6. Bring a friend. You will be encouraged to hear your friends going OOOH and AAAAAH when you do – and if nothing else, you can keep each other awake and share stories.
  7. Be sure your family knows where you’re going and when you’ll be back (if they aren’t coming with you).

There is always more, of course, but ultimately we suggest that when possible, you consider joining us when we schedule a workshop or field expedition.

Happy space debris hunting to you!

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.

Sneaky Night (and Daylight) Photo Processing Tips

 

Did you attend the Sneaky Night (and Daylight) Photography Processing Tips event held at Adobe in San Jose, California on July 23, 2018? Welcome!

The topics covered include these:

Let’s Start With a Pop Quiz

The Equation…

Or asked another way. Do these look like they might be the makings of an interesting shot?

Three Nuns Thumbnails

The Answer To the Pop Quiz

Combining the images shown in the thumbnails, nets this Interesting star trail.

N-604259-361lstr

“Long Streaks” Star Trail from 112 separate photos

Creating the Star Trail component above is discussed in detail in our NP105: Creating Star Trails & Timestacks Webinar – it’s an interactive 2 hour course with notes, a recording, and practice files. We run that webinar approximately quarterly next event is July 25th. Details  covered include how to set up the shots, configure the camera settings, and combine the images using various tools.

Adding that bright frame with a bit of selection and masking to the star trail image nets this:Reaching for the Sky

And that MUST be interesting because it garnered 80,000 views in just a few days. How do you do this bit of Photoshop Magic? Over the years, we’ve shown quite a few methods for accomplishing this. For example in Foreground – o – Matic we illustrated how to use the quick selection tool. That may work well here because the rock has a nice crisp boundary. Other methods that may work include “thresholding” and Color Range selection.

Thresholding to create a mask:  We’ve described this before. Briefly this is how it works. Select one of the images – one with contrast between the sky and foreground.  Duplicate that image (Ctl/Cmd -> J). Then use Image -> Adjustments -> Thresholds and slide the carat left or right until it has selected what you want (mostly black or white). Paint out the stray areas with either a 100% black or white brush as appropriate.  When done, you have an image you can use as a layer mask. The trick to doing this is to select the black and white image, EDIT an existing layer mask, and paste the black and white image as the layer mask.

 

Photoshop Processing Tips

  • Do work on a calibrated free-standing display in a dim, consistently lit room.
  • Do NOT attempt to process important images on a laptop monitor. You will frustrate the dickens out of yourself trying to get consistent color, brightness, and so forth on a laptop monitor or in an uncontrolled lighting environment. The monitor display angle can cause subtle to dramatic differences in color, saturation, brightness.
  • Do make an action and assign it to a hot-key if you find yourself repeating that operation frequently… E.g. I have an F9 key to apply a contrast enhancement adjustment curve
  • Do name your layers sensibly. You may save yourself a world of hurt.
  • Do NOT crop too early – save this step for last.
  • When combining dark and light subjects (e.g. daylight-like and night) it’s usually best to have very crisp selections – not feathered selections.

Gallery of Photoshop Hot Keys

These hot-keys are described for Windows users. I use these ALL the time. Some have no menu equivalent. You can translate from Windows to Mac as follows:

Ctl -> Command
Alt -> Option
Shift -> Shift

Layer / Layer Mask shortcuts:

  • Duplicate layer dialog allows you to duplicate into another/new document!
  • Ctl-J: Duplicate the current layer
  • CtlAltShift-E   Merge visible layers to a new layer as a COPY.
  • Shiftclick on layer mask to turn it off or on.
  • Ctldrag layer mask to move it to another layer.
  • Shiftdrag a layer mask to Invert it and move it to another layer
  • Altclick a layer mask to EDIT it.
  • Altdrag a layer mask to copy it. Toss in Shift to invert the mask.
  • Shiftclick a layer mask to turn it on/off
  • Altclick quick mask icon to create an inverse layer mask from a selection
  • Do not be afraid to duplicate and adjust a layer for the sole purpose of creating a mask!

Selection shortcuts:

  • Ctlclick on layer mask to create a selection from that layer mask.
  • Ctlclick on a channel e.g. RGB, R, G, or B to make a selection based on brightness.
  • Sometimes Select -> Modify -> Expand or Contract (by 1 pixel) helps to fine-tune a selection. Feathering seldom works well for compositing light and dark images.


Sneaky Tips
Sneaky Tips
Notes from "Sneaky Tips for Processing Day and Night Photography"

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

 

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