Milky Way Photo - My process the first time out
“A broad and ample road, whose dust is gold,
And pavement stars—as starts to thee appear
Soon in the galaxy, that milky way
Which mightly as a circling zone thou seest
Powder'd wiht stars.”
― John Milton Paradise Lost
I hoped that at least one of our stops in Peru would be somewhere with a dark sky as I've really wanted to learn how to take dramatic night sky photos. So to prepare I did research (big surprise, huh???) I'm thrilled to be able to pass on what I learned and tried. And I'd love to see any pics you take and hear what worked for you.
My first question was "How do people take pics of the Milky Way if we're IN the galaxy?" Well, the answer is that we shoot the core of the galaxy.
I knew I needed dark skies, which I don't get in the 'burbs of Chicagoland. But I started researching where to look in the sky. In the Northern Hemisphere, it's generally south and over the horizon. That would make some cool shots with scenery in the foreground. (Well, it would someplace other than Illinois. I suspect that where ever we have dark skies, my foreground will be cornfields and windmills. )
We were headed to the southern hemisphere, so I did more research. Down there, you generally have to shoot straight into the night sky. I was planning on taking my Platypod Max super portable tripod and checked to make sure I could get the camera angled high enough. Success, but.... I couldn't see the screen or view finder as they were angled down - almost at ground level. My camera doesn't have a rotating screen, but it is WiFi enabled and I can set up my iPad as a remote viewer and shutter trigger. That would work!
So, I'd solved the problem of how to manage the process physically, but what about settings? I knew I needed to have a long exposure to let enough light into the camera, but that creates a couple problems. The earth is moving, so a really long exposure would mean that I would get star trails. That could be cool, but not for this shot. I could go with a shorter exposure, but set my ISO really high. That makes the exposure time shorter, but creates what we call a "noisy" picture. And on a dark background, that's extra noticeable.
All the articles and tutorials I read offered the same basic solution - take multiple shots with a fair amount of noise and "stack" them in photoshop to reduce the noise. There are all kinds of complicated math formulas on how that works, but I am not going to cover that here. Suffice it to say that it does "smooth" the picture without losing much detail.
The first night in our hotel in Sacred Valley I was way too tired to shoot, and it was cloudy. The second night was much better - I had energy and the clouds cleared. I enlisted my husband to be my assistant and we went out to the hotel driveway. There were lights, but we found a relatively dark area. When we looked up, we were able to see the core of the Milky Way VERY faintly. I also used some sky mapping software to make sure I was looking at the right thing. I use Stellarium. They have free open source software for the computer and a charged app for iOS and Android. It was definitely worth it for this shot alone and I do hope to use it more often.
I started with some basic settings and set the camera up on my little portable tripod (It's called a Platypod Max - and it's awesome!) and pointed it towards the sky. I went through a little trial and error, but ended up with these:
No shutter delay - I should have done a mirror lockup to minimize shake, but completely forgot. If I'd not had the tablet to use as a remote shutter release, I would have set a 2 second delay to minimize camera shake.
ISO 5000 - normally this would be awful, but I knew I'd be combining shots.
Aperture f/4 - I wanted to let in a lot of light, and I knew everything I was shooting would be far away, I didn't need to worry about items on different planes being out of focus. See my note towards the end about something I'll do "next time".
Focal length 24mm - there were too many distracting objects in the area for me to use my wide angle. And my 24mm-105mm lens doesn't lock at any other focal distances. So since it was facing up, 24mm was all I could do.
Exposure - 15 seconds.
White balance - I just left it on Automatic, but I shoot in RAW so I knew I could change it in post-processing.
And this is basically what I got. Bleh. But it was exactly what I needed. If you look closely, you can see the galaxy. For this image, I took 4 shots - one after the other - without moving the camera or changing the settings. Next I uploaded the shots to Adobe Lightroom and made some basic edits - I upped the clarity, dehaze and contrast settings a bit.
I then opened the files as layers in Photoshop. My first task was to make sure they were perfectly aligned - the earth had moved slightly and therefore the stars had shifted on the screen. I started with the bottom two laters and lowered the opacity of the upper of the two layers to around 30%. I zoomed way in on a bright star and shifted that upper layer around slightly until it was aligned with the bottom layer. I then changed the opacity to 100% and did the same thing with the next layer, etc. When everything was aligned, it was time for the magic. I made sure the bottom layer stayed at 100% opacity and then decreased the opacity for each layer above - 75%, 50% and 25%. Everything averaged out and the noise was dramatically reduced!
I chose my next steps of post-processing simply based on what was more comfortable to me. I flattened the image and saved it as a tiff file (the default in my photoshop app). I then adjusted it more in Lightroom - mostly with clarity and dehaze - to draw out the stars. I will admit to photoshopping out that flagpole as it was really distracting.
Here's what I will do next time.
I'll do a lot more shots - probably ten.
I'd like to have a person or object in the foreground to make the shot even more interesting. In that case, I'll do one shot with them properly exposed and then do the exact same thing as in this series for the sky. Where we were situated, I really didn't have a lot of choice on the composition.
I will enable mirror lockup and see if I can get things even sharper.
That being said, there WILL be a next time. This was a fascinating process and I want to improve my technique. I also want to find some interesting ways to improve the composition. I am hooked on night sky photography! Now I just need to find some good dark sky locations.
Please let me know if you have any questions, comments or suggestions. And please share any fun photos you capture!