What is the Milky Way?
So, what is the Milky Way? Well, technically, you, me and everyone else on this big blue rock hurtling through space, are in the Milky Way galaxy.
When you look up into the sky, every star that you can see in the night sky is part of this galactic thing called the Milky Way. So when you ask, “How do I find the Milky Way?” what you actually need to know is, how to find the Milky Way’s center–that really bright part of the Milky Way you see in all of the photos.
When can I see it?
It can be a bit of a pain to set out on your first excursion only to find the Milky Way is not visible at that time of year. Not many know this, but the night sky has seasons. About mid-March through mid-October is the best Milky Way Season in pretty much any part of the world.
Technically, the Milky Way can be seen at any time of the year, but when shooting in the Off Season, September to April, we are only able to see the dimmer parts.
Pretty much anywhere in the world, on any dark night, it’s almost always possible to see at least a portion of the Milky Way’s plane. But, on really dark nights, during the right time of year and the right time of night, it can be found arching across the sky.
Another fun fact: Where you plant your tripod also determines what part of the sky the Milky Way will be in. What do I mean by that? For those of you, like me, in the northern hemisphere, the Milky Way is visible in the southern half of the sky (Trivia: Over 80% of the worlds population lives above the equator.) In its Off Season, it barely rises above the horizon. But for those of you shooting from the upside-down southern hemisphere, it will be directly overhead, especially right in the middle of Milky Way Season, around mid-June.
JUST LOOK UP!
First thing you will notice, even if you are in a dark enough place, finding the Milky Way with the naked eye is not as obvious as it appears in all of those long exposure photos you see.
Find as dark an area as possible, away from the light pollution of the cities. Make sure you’ve brought plenty of your own light though, in the form of flashlights and headlamps. And fresh batteries for your lights and your camera! Since you will be out there for a while, bring some snacks and a bottle or two of water. Maybe a grande vanilla latte too, if it’s cold.
It is best to scout locations before it gets too dark, lining up an interesting foreground or objects to include in your shot. Give your eyes a good 20-25 minutes of getting used to the dark, so they can adjust. Use this time to look around, set-up your gear, and get settled in.
Be courteous. Make sure not to shine any bright lights towards you or your fellow photographers. Don’t turn on the dome lights of your car either.
If you learned to recognize constellations as a kid, you should have no trouble finding the plane of the Milky Way. Growing up, I use to marvel at the night sky and could pick out most of the constellations. Now, that I’m much, much older, I still marvel at the night sky, but have forgotten how to find constellations. Now I found them with a map or an app.
I’m not going to go into the hows/wheres of finding constellations, Google has that covered, as well as, some apps, but you will generally want to look to the southern skies for the following constellations.
• Scorpius: It’s characterized by the star Antares, also know as “The Heart of the Scorpion.” Antares is one of the brightest stars in the sky and it has a distinct orange-yellow color, making it stand out from many of the other stars.
• Sagittarius: Situated almost exactly at the brightest part of the Milky Way.
• The Summer Triangle: This part of the Milky Way contains three more of the brightest stars in the sky: Vega, Deneb and Altair. They can be found high in the sky in May, June and July.
• Cassiopeia: This one’s a bit easier to find because it’s shaped like a giant “W.” Cassiopeia is visible almost all year in the northern part of the globe, as it’s one of the more northerly constellations, sitting adjacent to Polaris, the “North Star.” It will be in the northern part of the arch, should you be able to see it all.
• Crux or the Southern Cross: For those of you shooting from the southern part of the globe, Crux forms an almost perfect cross with some of the brightest stars in the sky, sitting right on the Milky way.
• Orion: This part of the Milky Way is the easiest to see in the “off season” from September through April. It’s recognizable by looking for the three bright stars that make up Orion’s belt.
These are the main constellations for finding the Milky Way. Today you can use a smartphone app to help you find and recognize them. In no time, your explorative sessions of gazing into the night sky will allow you to become quicker at recognizing them.
Even if you’re not trying to photograph it — Enjoy marveling the skies!
Apps That Can Help Find the Milky Way
A few favorite apps for finding the Milky Way’s bright galactic center.
Here is a quick overall look at each one. Use the link to go to their site and learn more.
PhotoPills for iOS
PhotoPills for iOS is a great app for photography planning. It includes an “augmented reality mode” and 2D Milky Way planner, which no other app provides. The 2D Milky Way Planner allows you to simulate the location of the Milky Way as an overlay on top of a map. This makes it easy to plan your shooting position and allows you to align landmarks with the Milky Way ahead of time. Especially as you’re scouting locations before it gets dark. Those PhotoPills folks were kind enough to also put together an extensive guide for planning and photographing the Milky Way.
SkyGuide for iOS
SkyGuides amazing feature is that it has a photorealistic representation of the night sky, allowing you to orient your iPhone to line up with where the Milk Way will be that night.
Learn more about how to use it, and how Nick Risinger, creator of skysurvey.org traveled the globe to capture more than 30,000 exposures of our night sky to build it.
Stellarium Mobile for Android
It includes Skysurvey’s mosaic for visualizing the Milky Way, but it’s at a lower resolution than the iPhone’s SkyGuide app. One trick I’ve read, is to turn the Milky Way brightness up to about 7 in the “Advanced” settings. Stellarium Mobile uses your phone’s compass and accelerometers as you orient your phone, to guide you towards the Milky Way’s location. There’s also an iOS version of Stellarium Mobile.
One of the best tools for finding the Milky Way before you leave the house, or just for the shear fun of exploring what’s in the sky–is Stellarium.org. An open source desktop computer app, which is free on Mac, Linux and Windows.
The lens you use is an important factor in image quality. Focal length and aperture size are the two basic traits of a lens that we will look at.
Which Lens Is Best?
You will generally want a wide angle lens. Look for a 24mm or shorter if you have an APS-C camera, or 35mm or wider for those of you on a Full Frame Camera. If you’re shooting with a 4/3 camera or smaller sensor, a 16mm or shorter will do best.
As you already know, a wide angle lenses captures a larger field of view (FOV), which will allow you to capture a larger area of the Milky Way sky.
Longer shutter speeds create star trails as the earth rotates, which you don’t want. Well, not in this lesson at least. Using a shorter focal length/wide angle lenses allows you to get by with longer shutter speeds.
Earth-rotating-caused-star-trails generally happen beyond 30 sec or so, depending on your focal length and where you are shooting.
Simple rules to prevent star trails…
There are several rules that astrophotographers use to guesstimate what shutter speed should be used to prevent “star smears.”
On a full frame camera, there is the “500 Rule” — Take the number 500 and divide it by your focal length, this will be the maximum number of seconds before star trails are visible. — A 24mm lens; take 500 and divide it by 24, you’ll get 500/24=20.8 — A 20 second shutter speed. Any longer than that and the stars may not be pin-sharp.
With the 17-40mm f4L lens, the maximum time (500/17) is right at 30 sec.
So, wider equals more Milky Way and longer shutter times to capture more light.
For APS-C cameras the rule becomes a “300 Rule,” so the same math, but now with 300.
That same 24mm lens on an APS-C camera would max out at about 13 seconds or so, while that 17mm will get you out to about 18 seconds.
If you have an APS-C sensor digital SLR that came with one of those 18-55mm kit lens, this will provide a relatively wide angle 18mm, at maybe f3.5
Another interesting phenomenon–the direction you point your camera in the night sky will affect the speed at which stars move, just due to the rotational angle of the earth. It also affects the direction and shape of star trails.
As with any other exposure, determine what maximum shutter speed will work best, via the above “rules of thumb” and then adjust accordingly.
As Always — Experiment!
Another important thing that will affect how much light you can gather in your Milky Way shots is the aperture or f/number of the lens. The f/number should be at the lowest number possible; remember smaller f # equals a larger aperture opening– f/2.8 or larger. Lenses with apertures of f/4.0 or smaller are not recommended, as they are not able to collect enough light for a proper exposure without resorting to higher ISOs, resulting in noisier images.
Which one to use? Photography is just one big balancing act. Both in setting exposures, also in buying the toys needed to explore more image opportunities.
Fast wide-angle lenses are available from pretty much every major lens manufacturer. Three manufactures; Samyang, Bower and Rokinon, produce great lens for astrophotography, as well as, other applications. They make most of their lenses available for at least Canon, Sony and Nikon, along with some for Fuji, Pentax, Olympus and Samsung bodies.
Many of the nightscapes you see are shot with a Rokinon 14mm f/2.8 (Rokinon FE14M-C 14mm F2.8 Ultra Wide Lens for Canon (Black) - Fixed), or Rokinon 24mm f/1.4 (Rokinon 24mm f/1.4 ED AS UMC Wide-Angle Lens for Canon). They are wide, fast and sharp enough to deliver amazing results. And most important, they’re inexpensive compared to ‘Name brand’ lens.
Remember, these lenses are all Manual Focus only, so they will take more patience and practice than the autofocus lenses you are used to shooting with. But at about a quarter of the price of the top-of-the-line Canon or Nikon lenses. Their image quality often match or exceed those name brands.
Once you’ve found the longest shutter speed you can get away with, with the aperture at its maximum to gather as much light as possible, you’ll need to start turning up the camera’s ISO to produce the proper exposure. Caution–this affects the amount of noise in your image too.
An ISO is adjusted as the “third leg” from your aperture and shutter speed. There are several ISO “rules of thumb” or “sunny-16 type rules” for a Milky Way exposure that many photographers talk about, such as; 30 seconds, f/2.0, ISO 1600. It just comes from their experience.
You are trying to achieve an exposure balance between brightness and dynamic range, while keeping noise down. ISO 3200 is about the maximum you should go on most of todays digital cameras. ISOs higher than 3200 will work if needed, but they may produce overly bright stars, with noise in the black sky. The best star color seems to be at ISOs between 800 and 3200.
As you adjust shutter speed or aperture, adjust the ISO reciprocally one stop for each change in shutter speed or aperture settings.
Use the Zoom-In-Feature of your camera's image review to check for star trails. If you see star smear, either decrease your focal length, go to a larger aperture, reduce your shutter speed, or increase ISO as needed, shoot again, check again, repeat as necessary.
The important part to remember is, a longer focal length lense will require shorter shutter speeds to prevent star trails — which equals less light captured — needing a higher ISO. All of which makes shooting the Milky Way more difficult.
I have a really sharp vintage Pentax 50mm f1.4, but its maximum shutter time for Milky Way shooting works out to only 6 seconds. Having an aperture of 1.4 helps, but I still need to crank up my ISO past my “comfort level” to capture enough light. My vintage Pentax 35mm f2.8 only gets me out to 9 sec. So, neither one is good for Milky Way shooting, even with the large aperture, so I go to my 17-40mm, which is “only” an f4.
If the stars are still streaking, you may need to reduce your shutter time. While the settings I have suggested should work, about 85% of the time. You may still need to make some small adjustments. You cannot usually rely entirely on what the photo looks like on the back of the LCD, it will be brighter than you expect.
I recommend using the histogram to find the proper exposure.
Every camera is different, but all of them feature some way to view a histogram graph of the exposure. To activate the histogram you may have to explore your menus or check your instruction manual.
There is no “right look’ to histograms, you are simply working towards a histogram that shows peaks toward the center of the graph. Sometimes it may be difficult if you are using a relatively slow lens, which may be forced to expose to the left. Try to avoid these underexposure shots, they will be very noisy. Exposures with histograms to the right are slightly safer, but harder, since it is a dark sky, unless there is substantial light pollution or if the moon is bright.
Understanding how to read your camera’s histogram will help you get the best results from your astrophotography. Experiment and do what you can to push your camera to capture more light without compromising quality. Don’t forget to check your image review often, zoom in on the LCD to check that focus is sharp. Double check the histogram’s information.
Once you find an exposure that works, you should lock it down in Manual Mode for the rest of the night. Just double check each image. Just to keep things interesting and to improve your chances of getting a great shot, re-compose your frame often.
If you find that you are having a rough time, and keep exposing to the left or underexposing, it may be time for a better lens.
Note: these suggestions are all for Canon, so make sure you click on your brand of camera.
Photography and photographers... A look at both. Blame it on the light.