To capture the Milky Way, you will need (1) a dark-sky site, (2) a camera with manual settings, and (3) a sturdy camera tripod (or a tracking mount if available). The image below was taken with just a point-and-shoot camera, which means if you have a DSLR camera, you can capture images far better than this! This tutorial will guide you on how to capture it on your first attempt.
Here’s a more recent Milky Way image taken on November 3, 2012:
For an archive of my Milky Way photos, click here.
Finding a Dark-sky Site
A dark-sky site is a place where you could safely conduct observations with minimum amount of light pollution. Ideally, it must have a clear view of the southeastern horizon to give you an unobstructed view of the Milky Way.
Best Time to Observe
It is advisable that you conduct your observations/imaging sessions during the time when the Milky Way is very prominent in the sky, usually during months of March to May each year. Since the Milky Way is only visible on a dark moonless night, in order to maximize your chances, it is advised that you conduct your imaging session on a date near a new moon. During this time of the year, you will see the Milky Way rising in the southeastern horizon at around 2-3 am and will be prominently visible from past midnight until sunrise. You will then have approximately a 3-4 hour window, but don’t worry, because you will only need 30 to 60 seconds of exposure time to take a decent Milky Way shot.
The starmap below shows how the Philippine sky (my locality) would look like at around 3 am, facing southeast, during the months of March and April each year. You can just use an app called Google Sky Map (for Android phones, just search the Market) or a freeware called Stellarium to navigate the night sky and help locate the Milky Way with ease. All these programs are downloadable for free on the Internet.
Spend a few minutes to familiarize yourself with the sky. It takes around 30 minutes for our eyes to fully dark- adapt. Note that your eyes must be dark-adapted before you could see the Milky Way. Locate it first before attempting to photograph it, so that you would know where to point your camera. If you are having difficulty locating it, feel free to leave a comment below stating your location (city, country). Note however that while as much as I would like to respond as timely as possible, my current work schedule has been very tight lately and thus I can only address queries during free time. Please allow a week or so for me to respond. :)
Recommended Camera Settings
It is assumed that your camera has a manual setting that allows it to take exposures (the amount of time the shutter is left open in a single shot) from 30 to 120 seconds. Use a wide-field lens and make sure that it can be focused at infinity.
Attach your camera to its tripod. Make sure that it is properly mounted since the smallest amount of vibrations will greatly affect your image. Set the exposure time to 30 seconds. Set the f-ratio/f-stop to its lowest value (widest opening of the iris diaphragm to accommodate more light, i.e., f/2.7 is preferred than f/8). Set the ISO value to moderate (If maximum ISO value is 800, set it to 400). Check that you are focused at infinity, and the flash mechanism is turned off. Make sure you are pointed to the right region in the sky. Turn on the camera’s time-delay shutter feature to avoid vibration caused be pressing the shutter from affecting the image (10-second time delay will do). When you are ready to shoot, point it to the target, press the shutter, then wait. Your camera should be able to capture it on your first attempt.
Adjusting the Exposure Time
As a general rule, most settings described above are left unchanged except for two: exposure time and ISO value. By increasing the exposure time, you will notice that the image becomes brighter. It is because more light is accumulated in each shot. With a non-tracking mount/tripod, you can increase the exposure time only up to a certain extent (usually up to 60 seconds) before you start to notice that stars no longer appear rounded, but rather as steaks of light (called star trails).
The trailing of stars is due to the Earth’s rotation. Objects in the sky appear to move from east to west at the rate of 15 degrees per hour, which is effectively counteracted by tracking mounts (if available). Tracking mounts would allow up to 3 to 4 minutes exposure time with no trails visible as compared to a non-tracking mount/tripod which is limited only to less than a minute or so. It is recommended that you start with an exposure time of 30 seconds then increase this value by a few seconds or so, until you have determined the optimum exposure value that will give you the most amount of detail, while at the same time, keep the stars from trailing. Keep in mind that as you increase the exposure time, star trails become more evident. It would be helpful to experiment with different ISO values and exposure time.
ISO Speed and Noise
Increasing the ISO value (or the ISO speed) would cause the sensor (CCD/CMOS) of your camera to become more sensitive to light. While greater sensitivity means more details can be captured in shorter exposure times, it would also mean introducing more noise. For low-light photography, it is recommended that you keep the ISO value from moderate to low in order to minimize noise (I would recommend that you set the value to not more than 50% of the highest ISO setting of your camera.). The image below illustrates the effect of different ISO values on the noise level of the image.
Milky Way Photos of Fellow Astronomy Enthusiasts
Here are some Milky Way images taken by fellow astrophotography enthusiasts. If you have captured a great Milky Way photo by following this tutorial, just leave me a note and I will include it in the list! :)
Clear skies and happy shooting!
For tutorials on how to get started with astrophotography, click here.
For DIY astronomy projects useful for astrophotography, click here.
To subscribe to this site, click here.
© Anthony Urbano (Manila, Philippines)