Photographing the Night Sky with your DSLR Camera
by Dr. Robert Berdan
October 17, 2011
My first picture of the Night Sky taken with an Olympus OM-1 SLR camera on tripod on Kodachrome 64. The stars making up the big dipper are circled. The stars appear to move in an arc around the North star (outside the picture in the top right) due to the Earths rotation. Midland, Ontario, 1972.
Photographing the night sky requires nothing more then a digital single lens reflex (DSLR ) camera and a tripod. You can use almost any lens though its easier to start with a normal (50 mm) or wide angle lens and set it to its widest aperture. Fast lenses with F2.8, F2 or F1.4 will let you take shorter exposures. With a DSLR you can preview your images on the LCD screen after shooting and make adjustments to the exposure if necessary. To determine the best exposure try your camera in A or Aperture priority mode - some cameras work great this way even in automatic exposure mode. If you don't get good results try setting your camera to M or manual mode and adjust the exposure until the exposure looks right on your LCD screen. If you know how to check the levels histogram - even better. For night photography you can start with 10, 20, 30 seconds. If its really dark its almost impossible to overexpose your shots at night. If you need longer exposures you can set the camera to B or Bulb mode which means the shutter stays open as long the shutter button is depressed. If you use Bulb mode it helps to have an electronic cable release so you can lock the shutter open.
A good subject to start with on a clear night are constellations. As your confidence improves try and capture the milky way, meteors, comets and even lightening. Below I show a series of night sky photographs taken with a digital single lens reflex camera and various wide angle lenses. it's easier then you think. Be sure to remove any filters from the front of your lens. If you own a compact digital camera, you can experiment with night shooting mode, fireworks mode etc, but be sure to set the focus at infinity if possible. Some compact digital cameras can take great night shots, but most of them are not good for this type of photography.
Orion constellation, Fort McMurray - January around midnight. 20-30 mm Zoom lens, At F2.8. Stars around the edge of the photo are not be sharp, by stopping the lens down 1 F-stop usually results in sharper stars at the edge of the photo, but you will need to double the exposure time. When the exposures exceeds about 1 minute, you will begin to see star trails. There is a simple formula to determine how long the exposure can be before you see star trailing, take the number 600 and divide it by the focal length of your lens and it will provide the maximum time in seconds you can expose the picture before seeing trails.
Maximum length of exposure before you see star trails
600\50 mm lens
600\24 mm lens
600\15 mm lens
600\10 mm lens
The Big dipper is the easiest constellation to see - the stars have been circled to see them better. If you have really good eyes you can see a double star in the handle of the dipper made up of two stars named Alcor and Mizar. If you camera is focused properly you can also see these two stars in your pictures. The thin streak is a Perseid meteor - certain meteor showers show regularly, the Perseid meteor shower has been observed for over 2000 years and appears around August 12-13 each summer in the northern hemisphere.
There are many subjects you can photograph at night. If the sky is clear you can try capturing star clusters and constellations. Set you camera to ISO 400-800, set you lens to manual focus and put it on infinity. Point at the stars and shoot. For critical focus, you can select a very bright star point your camera at it, turn on Live view so you can see the star on the screen, zoom in 10X and then adjust your focus carefully so the star is as small as possible with little or no colour fringing. This should result in infinity focus which is what you need to get pin-point sharp stars. Out of focus stars will look bloated when you enlarge your pictures. Some lenses (e.g. Nikon) you can simply set them to infinity and they will be close to infinity focus) others such as those from Canon may focus past infinity so you need to check your pictures on screen and zoom in - if the starrs are not pin points - adjust your focus and check the photos on your LCD screen. You will not be abler to see or focus on the stars through your viewfinder - at least I can't! Some photographers use a magnifier finder to help them focus - this works for the moon, but I have not found it helpful for stars. You should check your focus about once an hour as it may change due to a drop in temperature or accidently touch the lens.
Viewing and photographing the milky way requires a reasonable dark site. When you take a photograph of it, the camera will capture more detail then you can see with your eyes (see below).
This is a photo of the Milky way taken with a 24 mm F1.4 Canon lens at F2.2 - 30 second exposure ISO 1600
TIn this photo the Milky way extends right down to the horizon, The Crossing resort, Grasslands National Park in Saskatchewan.
When you spend time looking at the night sky especially on a moonless night you begin to see satellites flying overhead and you will also likely see several meteors that streak across the sky. If you know where to look you can even see distant galaxies like Andromeda with your naked eye - it appears as a fuzzy smudge below the constellation Cassiopeia or the "W" in the Milky way (see below).
Andromeda Galaxy, a satellite passing over head and the finer streak is from a falling meteor or shooting star. There is also a faint green Aurora glow in the sky. Grasslands National Park - from the Crossing Resort. Meteors appear like fine scratches. Satellites sometimes have a pulsing light and tend to be uniform in thickness in the photos.
On some clear nights you can see the stars shortly after sunset - Prelude lake, NWT 24 mm F1.4 lens, Canon 5D Mark II
Aurora Borealis reflecting off Prelude Lake near Yellowknife in the NWT - notice the Pleiades star cluster, also called the Seven Sisters. This open star cluster can be seen with the naked eye rising in the East. The Aurora is rare in southern latitudes, but can be seen on most clear nights outside of Yellowknife which sits under the Aurora oval (57-65° N). The Aurora is sometimes visible further south and you can increase you chances of seeing and photographing it by subscribing to one of the many websites that send out Aurora alerts. I discuss Aurora photography separately in several articles on this site - e.g. Aurora Photography.
Noctilucent clouds are high altitude clouds visible at twilight. They are made of crystals of ice that form between 75 to 85 km up in the atmosphere. They are most commonly observed in the summer months at latitudes between 50-70° north and south of the equator. These clouds were photographed at Prosperous lake outside Yellowknife in late August. The green light is from the Aurora Borealis.
Comet Kohoutek - November 1973 outside of Calgary - note the Pleiades star cluster on the left side of the picture. Photographed with film, Ektachrome 1600 about 30 seconds exposure. Comets are relatively rare occurrences, but are often mentioned n the news and you can find out more about them and their occurrence in a variety of astronomy magazines.
Moon, faint Aurora, Comet Kohoutek - November 1973 - Outside Calgary.
Another subject that is easier to photograph at night is lightening. If the lightening is off in the distance, set you camera up on a tripod and put it on B or bulb mode. Hold the shutter down until you see lightening strike then release the shutter and check your LCD finder. I recommend starting with 10-30 second exposures at F4-F5.6, focus at infinity. ISO 200-400 works well. If you leave the shutter open too long, you will get too much light from other sources so a little bit of experimentation is required. If lightening gets too close, get inside your car and attach your camera to a window mount - see more information on window mounts here.
Lightening over Cochrane - photographed from the highway above town in the early morning hours.
Photograph of the Moon
If you have a telephoto lens 200-400 mm, you can use it like a telescope to photograph the moon. The main problem is that your camera will tend to overexpose the moon unless its near the horizon. If this occurs use your exposure adjustment button and try setting it to -2 or -3 stops under exposure and you should begin to see details on the moon. Also set your ISO speed up to 400 or higher so you can use short exposures. The moon moves fairly quickly across the sky and the more magnification you use, the faster it appears to move.
Lunar Eclipse, 300 mm Telephoto lens, Nikon D300, ISO 800, 1 sec Feb 20, 2008 on a tripod - I also used a cable release to reduce shutter vibration.
Left is my photo of the sun taken with a Celestron C6 telescope (1500 mm F10) and my Nikon D700 camera attached, ISO 800, 1\320 sec and on the right a photo of the sun from NASA's Solar Dynamics Observatory - both on Nov. 5, 2011. Note the large group of sunspots coming into view on the left size of the sun. Images like this can be taken using a telephoto lens, BUT ONLY IF YOU HAVE A PROPER SOLAR FILTER which can be purchased at most astronomy stores. Looking at the Sun directly through a telephoto lens when the sun is high in the sky can cause blindness and damage your camera's sensor. The only time you can photograph the sun directly with a telephoto lens is around sunrise and sunset as shown below.
Sunrise taken with Nikon D300 300 mm F2.8 lens + 1.7X teleconverter - you can take pictures like this with your telephoto lens because you are looking through the edge of the earth's atomosphere, but you should not stare at the sun through the lens or you can damage your eyes. Note the distorsion in the shape of the sun due to differences in air density.
Things that will make shooting at night easier include a small flash light or head lamp, fine gloves or mitts, some star charts to find your way around the sky, a warm drink, a comfortable chair, a set of binoculars and a good friend. You don't have to go anywhere, you can start in your own backyard if you own one. My backyard has lots of light pollution, but I have counted numerous meteors on summer nights and even photographed the Aurora in my backyard in the summer time (see below).
Aurora over my garage taken in August. Power lines and street lamps are a hinderance, but it's convenient. If I know there is a good chance for Aurora I head out of town and search for a dark site - sometimes I am lucky, then again often I am not. See my article on Aurora outside Calgary, on August 7, 2011.
Another interesting subject to photograph is the alignment of planets with the moon - conjunction. This picture was taken with Canon 5D 70-200 mm F4 lens, ISO 3200 Exp -2, 1\15 sec. On close inspection it was possible to see 2 moons around Jupiter.
Although I focus primarily on nature photography, I am always amazed at how many outdoor photographers ignore the night sky. You don't need fancy equipment if you own a tripod. A pair of binoculars will help you discover some of the fainter objects in the night sky such as star clusters, double stars etc. If your interest in the night sky grows you can join a local astronomy club - they even have star parties where they gather to share their passion under the night sky. You will never meet a finer group of geeks than at an astronomy club :-). Most of thes folks will gladly show you what they are looking at through their telescopes, so you don't even have to own anything except a pair of binoculars when you head out.
Star party (gather ing of astronomy enthusiasts) at Grasslands National Park - astronomers are teaching Park staff the constellations who in turn will teach visitors to the park. Astronomer uses a green laser to point out objects in the sky.
Astronomy enthusiasts often use red lights to keep their night vision and if they have laptop computers they usually cover them with red acetate. If you ever visit a star party be careful where you point your flash lights and be sure to run your bright car lights off if you approach at night - at least if you want to avoid being scolded.
if you find your self wanting to learn more about the night sky check out your local astronomy club and various astronomy web site. If you plan on buying a telescope it is a good idea to get the advice of an experienced hobbyist or at least read the Backyard Astronomy book which is probably available at your local library. I have owned several telescopes, but most of the time I use a pair of binoculars and my camera. My telescope buying experience suggests - don't buy too big or too heavy, start small and you can always upsize later. A good pair of binoculars is the best way to get started. If you have a camera, next time you are out at night or go camping - set up your tripod and camera and give night sky photography a try.
Clear Sky Chart for Calgary, Alberta
Click here for more information on how to intrepret the Clear Sky Chart
Links & Additional References
Tips for focusing on stars using Live View - excellent for Aurora photography to find infinity focus
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