How to Plan, Shoot and Edit a Milky Way Arch Panorama (Part II)
Note: This is the second in a two-part series about creating a Milky Way panorama. Part I covered planning and shooting. Below we go over how to put it all together in post.
In last week’s blog post, Matt demonstrated how to create the raw materials for a Milky Way panorama arch. I really enjoyed the post and was glad that he asked me to follow up with a tutorial on processing the frames he captured to stitch the final image.
Computer Software
To create a panorama from multiple images, you’ll need some type of software for your computer. When it comes to software, I like to keep it simple—until I can’t. For me, keeping it simple means working with software I already own and understand. In this case, that means working with Adobe Lightroom Classic and Photoshop. While there are other stitching programs out there, I have always been satisfied with the Adobe products. I already own them, so again, I keep it simple.
In general, both Lightroom and Photoshop are seriously robust and each have their own advantages and disadvantages. When it comes to processing panoramas, both programs work well. Lightroom is the more convenient of the two, and Photoshop offers more options and tends to create more realistic results when you have less-than-perfect captures.
What are less-than-perfect captures? In short, images that the software finds difficult to stitch together. This could be frames taken without a nodal rail or frames that don’t overlap enough, etc. In last week’s article, Matt showed how to create perfect captures that will be easy enough for either program to stitch.
Pre-Stitch Processing
Once you download your images, it’s time to start processing them. If you are planning to stitch (or “merge”) the images together using Lightroom, there’s very little processing that’s necessary beforehand. The reason is that the result of Lightroom’s Merge function is a panorama that is still a RAW file. This means you can do all your processing to the final pano after it’s created, rather than to each individual file before stiching.
Figure 1.
However, there is one exception to that, and that exception is Lens Correction. Why? Because correcting lens quirks will help the rest of the process go better, particularly in regard to vignetting. Removing vignettes will help the exposure look consistent across the whole panorama.
The Lens Correction panel (Figure 1) lives in the Develop module, and it’s the one place you must visit before merging your images into a panorama. Here you can see I’ve checked the Remove Chromatic Aberration box as well as the Enable Profile Corrections box.
Checking both of these boxes tells Lightroom to correct any aberrations associated with that particular lens. At this point Lightroom will typically recognize which lens you’re using and apply the correct profile corrections automatically. However, if you are using a very old lens, or if you’re using a lens brand that’s different than your camera brand, you may need to manually input the type of lens you used. In the example in Figure 1, I had to choose Zeiss from the Make drop-down menu for before Lightroom recognized the lens as the Zeiss Milvus 2.8/15 ZE.
Once you have set the Lens Correction panel on one image, it’s time to sync that change across all the images of that set. From the thumbnails at the bottom of the page, first click on the image with the Lens Corrections. Next, hold down the shift key and click on the last image in that set. This will highlight (select) all of the images in the series. Notice in Figure 2, the cell for the first image I clicked on (the one with the changes) is white, while the remainder of the selected cells are light gray. This means that all the images are selected, but the white image is the “active” image. When we sync, the active image is the one that shares all of its settings with the others.
(If the image with the Lens Corrections is not white, simply click on the correct image. All images will remain selected—you will have just changed the active image.)
Figure 2.
With all of the images selected, click the Sync button (circled in red in Figure 3). (If the Sync button is not available, that means you have only one image selected. Return to the Filmstrip at the bottom and reselect the images.)
Figure 3.
Now, click the Sync button to open the Synchronize Settings dialog (Figure 4).
Figure 4.
Click the Check All button and then finish by clicking the Synchronize button. This will close the box and copy all of the settings from the active image to the selected images.
Figure 5.
Merging Using Lightroom
With all of your images selected and synchronized, it’s time to merge them into a panorama. From the Lightroom menu, choose Photo > Photo Merge > Panorama (Figure 5).
The next thing you’ll see is the Panorama Merge Preview box (Figure 6). The choices here are quite minimal. Projection (Spherical, Cylindrical and Perspective) is what determines the overall shape and look of your image. Simply choose the one that best represents your original vision. Because Matt used a nodal rail when shooting, the difference between Spherical and Cylindrical is nearly impossible to discern. This may not always be the case. Again, just choose the setting that produces a result you like.
Figure 6.
With this image, when I choose Perspective, I get the error “Unable to merge the photos” (Figure 7). If you get this error, simply choose another projection. It may or may not work. As I mentioned earlier, while Lightroom’s Merge to Panorama is convenient, it may not work in all circumstances.
Figure 7.
The remaining options are really just that—options. My preferred settings (which appear in Figure 6) are:
I keep the Boundary Warp at 0 and I check the Auto Crop box. This keeps Lightroom from stretching the image to fill in blank spaces around the edges, and instead crops out those stray spaces.
I keep the Auto Settings box unchecked. This keeps Lightroom from auto-tuning the basic adjustments in the final pano. I prefer to make my own adjustments.
I check Create Stack so that the panorama file is stacked with all of its source images in the Library module. This just helps keep things organized.
Click the Merge button at the bottom right of the Panorama Merge Preview dialog to create your panorama. Lightroom will begin merging your images, and you can track its progress in the taskbar in the upper left portion of your screen (Figure 8).
Figure 8.
Once finished, your image will appear back in Lightroom (as a RAW file), all ready for you to apply your favorite Milky Way edits!
Comparing Lenses
As you may remember from last week, Matt shot the raw materials with three lenses—the Zeiss 15mm Distagon f/2.8, Viltrox 20mm f/1.8 and Sigma 35mm f/1.4 Art. Here are those three panos created with Projection set to Spherical.
Figure 9. Nikon Z 6 with a Sigma 35mm f/1.4 Art lens. Multiple stitched frames shot at 8 seconds, f/2.8, ISO 6400.
Figure 10. Nikon Z 6 with a Viltrox 20mm f/1.8 lens. Multiple stitched frames shot at 14 seconds, f/2.8, ISO 6400.
Figure 11. Nikon Z 6 with a Zeiss 15mm Distagon f/2.8 lens. Multiple stitched frames shot at 16 seconds, f/2.8, ISO 6400.
The first thing you might notice is that the panos shot with longer lenses are darker, with fewer stars appearing in the sky. That’s because Matt needed shorter exposure times for the longer lenses, in order keep the stars sharp.
The next thing you’ll notice is that the images from the widest-angle lens—the 15mm (Figure 11)—do not merge well. The sky on the left side of the image appears uneven. Lightroom may sometimes have problems merging panoramas made with superwide-angle lenses.
Merging Using Photoshop
When using a very wide lens, or if you didn’t use a nodal rail—or if Lightroom is having trouble with the pano for any reason, discernible or not—you may have to take your images into Photoshop to do the stitch. The steps are very similar to merging in Lightroom. In fact, the first three steps are exactly the same:
Select first image in the series and go to the Develop module.
Go to the Lens Corrections panel and check Remove Chromatic Aberration and Enable Profile Corrections.
From the thumbnails at the bottom of the page, click on the image with the Lens Corrections (this should already be selected if you were just working on it), hold the shift key and click on the last image in the pano series. With all of the images selected, click the Sync button.
Now we start to detour from the Lightroom pano workflow. Before exporting to Photoshop, you can edit your images before merging. Stick with the big overall changes in the Basic panel, such as White Balance, Color Profile and the fundamental tonal adjustments. Remember you’ll be syncing these changes across all of your images in the set, so don’t make a change that might adversely affect one of the other images.
Once that first frame is suitably adjusted, sync the settings across the whole set in the same way as described above. Then look at each image to ensure that the settings work well with each frame. If they don’t, return to the settings and adjust as needed. Then synchronize them again.
Once all the frames in the set look right, select the whole series by clicking the first and shift-clicking the last. Then, from Lightroom’s menu, choose Photo > Edit In > Merge to Panorama in Photoshop (Figure 12).
Figure 12.
Next you’ll see the Photomerge dialog in Photoshop. Choose Auto from the Layout panel on the left and check Blend Images Together (Figure 13). You don’t need to check Vignette Removal or Geometric Distortion Correction, because you already fixed those issues in Lightroom; you don’t need to check Content Aware Fill Transparent Areas because we’ll tackle that manually later.
Figure 13.
Click OK. Photoshop will now start to create the panorama. This could take a minute or so. For our example, Figure 14 shows the final image that Photoshop creates.
Figure 14.
Next, from the Photoshop menu, choose Layer > Flatten Image.
For the simplest way to wrap up, choose File > Save and then File > Close and your image will return to Lightroom ready for your magic touch in the Develop module. However, if you are even somewhat Photoshop literate, there are some advantages to keeping the file open and continuing to work on it before sending it back to Lightroom. Read on. …
More Photoshop Edits
One of Photoshop’s more powerful features is Content Aware Fill, which is perfect for filling in gaps at pano edges that you would otherwise need to chop off with the Crop tool. In this example I wanted to keep a bit of sky over the Milky Way arch, so I left the blank corners, as seen in Figure 15. Content Aware Fill will help us quickly and intelligently fill in those blanks.
Figure 15.
After I crop the image (as seen above), I choose Layer > Duplicate Layer from the Photoshop menu. This keeps all of my edits on a separate layer and protects my original pano as a background layer.
Next I select the Lasso tool and draw a circle around the area that I want to fill (Figure 16). I don’t want to include too much excess area, but I also don’t want to cut it too close.
Figure 16.
After making the selection, I select Edit > Content Aware Fill, which is where a lot of magic can happen. In the Content Aware Fill dialog, everything masked with green is where Photoshop will look to sample data to fill in the blank area (Figure 17).
Figure 17.
By default, the Subtract paint brush is selected. Simply paint away any areas of green that you feel don’t need to be included in the sample; likewise, you can add to the sample by holding Alt (Windows) or Option (Mac) and painting to add green. Figure 18 shows how I painted away areas not similar to the area I want to fill. For example, I don’t want Photoshop to sample a starry sky when trying to fill foreground rocks. The Preview box on the right foretells the final effect.
Figure 18.
When finished, click OK, which will apply the fill and close the dialog. Figure 19 shows the result. Photoshop has literally made up information (based on the green-masked sample) and filled the blank area.
To continue filling in the corners, I return to the pano copy layer by clicking on it (Figure 19). Again I make a selection and proceed as above until all of the corners are filled. (Remember to return to the Layer 0 Copy layer between edits.)
Figure 19.
Once you are finished, you can flatten the image (Layer > Flatten Image), choose File > Save and then File > Close, and your panorama will return to Lightroom ready for final edits.
In Summary
Both Lightroom and Photoshop can create seamless panoramas of the night sky. Lightroom excels at being simple and convenient when using source images that are easy to merge. Photoshop can be used when images are less than perfect. This includes images made from superwide-angle lenses or frames that don’t overlap as much.
Regardless of which tools you use, making the time investment to learn how to create Milky Way panoramas will open up a whole new area for creativity in night photography.
Whether you’ve been making Milky Way panos for years or will start after reading this post, we’d love to see your images! Please share in the Comments section below or on our Facebook page.