|Hopewell Rocks, also known as the Flower Pot Rocks, are natural formations of sandstone and dark sedimentary conglomerate found in the Bay of Fundy in Hopewell Cape, New Brunswick, Canada. Camera sensitivities have become so powerful that you now can achieve astrophotography without specialized equipment.|
Imagine standing on the edge of a cliff in a remote area overlooking the ocean on a clear moonless night. The Milky Way is so bright that it reflects in the ocean, and the way it shoots up into the sky lines up with the small cove in front of you. Scenes like this are now much easier to capture with modern DSLRs and lenses. It takes some practice and a lot of patience standing around in the dark while your camera takes long exposures, but the results will make you glad you stayed up all night.
Separate Exposures For Sky And Foreground
In order to capture near-pinpoint stars, you have to limit your exposure time, or the rotation of the Earth will cause the stars to appear to move through your frame. I'm usually shooting at 25 seconds, ƒ/2.8, using ISO 3200 and a focal length of 14mm. This will give you stars that look close to pinpoints in a large print, but your foreground will be out of focus (and, most likely, underexposed) because you're focused for the stars at ƒ/2.8. For stars with minimal trails, as a rule of thumb, you can divide your focal length into 500 or 400 to get a maximum exposure time. (I prefer dividing into 400 for smaller trails.)
You could light up your foreground in the same shot, but it still would be out of focus. So in order to capture pinpoint stars and a well-exposed and in-focus foreground, you'll need to shoot separate exposures for the sky and foreground at different settings. You then blend them together in Photoshop. My foreground exposures will vary the focus point, ƒ-stop, ISO and exposure length, depending on the situation. I often try to shoot foregrounds at ISO 1600 or lower to get a cleaner image. If you want to make large detailed prints, then you'll need to be careful with noise and depth of field.
As always, you should be shooting in RAW mode to get the most out of your camera and editing ability. White balance isn't important to a RAW file, but it's important for the JPEG preview that you see on your camera's LCD. Most cameras also calculate the histogram they display based on the JPEG preview, so dialing in a white balance that comes close to what you might want your scene to look like will create a more useful histogram. On my Nikon D800E, I'll often use a manual white balance of 3700K, but it will depend on conditions. Perhaps there's a lot of light pollution or intense airglow, for example, which will affect the apparent color of the sky.
Long exposures and clear skies are often all that you'll need to capture a backdrop of stars, but perfecting the method requires a knowledge of the best camera settings for your project. If you plan ahead, you can even incorporate celestial bodies into a composition. Above: A long exposure of Otter Cliffs from Acadia National Park's Boulder Beach, Maine.
Utilizing your camera's long-exposure noise-reduction setting (dark frame subtraction) can be a lifesaver when it comes to reducing hot pixels in long exposures. The downside is that you'll need to wait twice as long since the camera will need to take a "dark frame" with the same exposure settings to compare noise floors. If you don't do any form of long-exposure noise reduction, be prepared to spend a long time healing hot pixels in postprocessing.
Composing With The Milky Way
Before you can shoot the Milky Way, you need to find out when and where you can see it. In the Northern Hemisphere, the galactic center is visible at night from mid-February to mid-November. Choose a location that has interesting foreground elements that work with the Milky Way, perhaps arching over a rugged coastline or mountains, or lined up with a river or road. The Milky Way looks the same every night (not counting for airglow and light pollution) so focus more on framing that uses the Milky Way as a compositional element.
There are a number of handy apps available for both Apple and Android devices that display the location, like SkySafari, Star Walk, Planets and Star Chart. If you have an iPhone, you can get the app PhotoPills, which shows the location of the Milky Way relative to any point on a 2D map, the perfect planning tool for landscape astrophotography.
Beneath the Milky Way, Screw Auger Falls plunges 30 feet into the Bear River, Oxford County, Maine.
You can capture pinpoint stars with even less noise by using a method that stacks multiple short exposures of the stars together before aligning them and averaging them. You can do this in Photoshop by masking out the foreground completely from each shot, aligning the images, combining them all into a Smart Object and using the "median" stack mode for the Smart Object. However, if you're on a Mac, you can make this process a lot easier by using the program Starry Landscape Stacker, available in the Mac App store (you can find more info here: sites.google.com/site/starrylandscapestacker/home). I've been using this technique with Starry Landscape Stacker and the results are amazing. I've experimented with taking 10 exposures of 10 seconds each at ISO 6400 and combining those, but I've also found that just five exposures work very well. The reduced noise level is still excellent.
The lupine fields in front of St. Matthew's Chapel, Sugar Hill, New Hampshire. Sharp long-exposure foreground shots will call for quiet nights. Exposure blending or stacking of multiple images can gain you a background of stars in pinpoint focus.
If you shoot multiple exposures for the sky and foreground, you'll need to blend them together in software. You can do this manually using Photoshop with layer masking, or you can try Photoshop's Auto-Blend Layers option. Another option is Helicon Focus, a program dedicated to blending exposures of different focal distances. The best tool will depend on the situation. I frequently use manual blending, often with luminosity masks, to make complex selections. For some scenes, it's as easy as a gradient mask to blend the sky with the foreground. You can find my basic tutorial on exposure blending on YouTube at www.youtube.com/watch?v=7k5bRHegiXA.
See more of Adam Woodworth's photography and his tutorials and sign up for his astrophotography workshops at www.adamwoodworth.com.
|Tips For Night Shooting
Gear and equipment for the best results with long exposuresFull-Frame Vs. Crop Sensor. A full-frame DSLR is the best choice for astro-photography, but I've seen great shots taken with APS-C crop sensors and even micro 4/3 sensors. Night photography really pushes image sensors to their limits, and a recent full-frame camera will get you the most dynamic range and the least amount of noise.Lens. Arguably the most important part of your astrophotography gear will be your lens. For wide-angle astrophotography, one of the best lenses is the Nikon 14-24mm ƒ/2.8 lens, which can be used on Canon cameras with an adapter. This lens is sharp, even at ƒ/2.8. You want a wide-aperture lens to let in the most light possible for your night sky exposures, ƒ/2.8 or greater, although most lenses that are faster than ƒ/2.8 aren't particularly sharp in the corners, resulting in soft stars. The Samyang 14mm ƒ/2.8 lens (also manufactured under the brand names Bower and Rokinon) is a very inexpensive full-frame superwide-angle lens. For APS-C crop cameras, the Tokina 11-16mm ƒ/2.8 is a popular lens.
Tripod. A sturdy tripod and secure head are a must. Astrophotography requires long exposures, usually 30 seconds or so for the sky, and often much longer for the foreground.
Remote Timer. A remote timer will be necessary to take exposures that are longer than 30 seconds, which you'll want to do when capturing detail in the foreground. I've found that most of the inexpensive remotes have a weakness in their cable design that breaks easily, so after replacing a few of those, I went with one by Promote Systems.
Focusing In The Dark. This will vary, depending on your lens. On my Nikon 14-24mm, if I put the focus ring at infinity, I know it's truly at infinity (of course, I always make test photos to be sure), but this isn't the case with all lenses. You may need to put your camera in Live View mode, zoom in on the LCD and manually turn the focus ring until you get the stars in focus. (You want the stars to appear as the smallest possible dot when zoomed in on the LCD.) When focusing for the foreground, you can use a flashlight to light up the foreground and use Live View to adjust focus while it's illuminated.
Light Painting. Shooting in the dark means you'll need to do very long exposures to get detail in the foreground and blend those shots with your shorter-exposure sky shots. But you can make the foreground exposure times shorter by using light painting, a technique where you use a flashlight to "paint in" the foreground. This can take a lot of finesse to avoid the light looking like it was just car headlights blasting your scene in a very flat manner, and sometimes it doesn't work at all, resulting in incredibly harsh shadows and specular highlights on things like wet rocks. I tend to use it sparingly and more often do very long foreground exposures for an evenly metered scene.