via Photography Blogger by Luis Argerich on 2/24/12
Photographing our own galaxy: The Milky Way is a great experience. From a dark location without light pollution the dusty band of the Milky Way is a wonderful sight to the naked eye and it looks even better in long exposure photographs. Summer in the North Hemisphere and Winter in the South Hemisphere is the best time to photograph the Milky Way and here’s a short article about how to do it.
Good preparation is critical if you want to get a good shot of the Milky Way. I use Stellarium (free) to forecast how the sky will look from any location at a given time. For the Milky Way, you will get a good shot around 3am in March, around 2am in April, around 1am in May, and at midnight on June. In July and August you the ideal times are from 9 or 10pm.
The brightest part of the Milky Way is towards the direction of Scorpius/Sagitarius. Look for those constellations on Stellarium and take note of the direction where you need to point the camera and the best time of the night to do it (when the constellations are higher in the sky).
Then you need to find a location that has little or no light pollution in the direction of your shot. This can be hard depending on where you’re at. Rural areas are fine but make sure the Milky Way is not in the direction of a town or city.
Setup & Taking the shot
To take a good photo of the Milky Way you need to avoid star trails. Use a very wide lens, a fast one if you have it and a solid tripod with a good ballhead.
The following procedure will help you frame the shot and take the best possible exposure.
First Stage: Framing
– lens wide open
– ridiculous ISO (12800,25600 etc)
– 2 or 4 second exposures
Use this short exposures moving the camera around to find the framing you like. The photos are useless but we are using the camera as an extra pair of eyes, eyes that are far more sensible to the light than ours.
Once the framing is found we move to stage 2, the exposure.
Second Stage: Exposure
– lens wide open
– ISO800 or 1600
– 20 seconds exposure
Take a shot and in the camera LCD examine the stars near the borders of the frame (not the center) if you see trails, then repeat with a shorter exposure. If you don’t see trails repeat with a longer exposure. Do this until you find the longest exposure you can afford without trails.
Note: when you check the stars for trails you might see the stars at the borders display a strange triangular shape. That’s called “comma” and is an optical defect on the lens. To solve that close the aperture 1 step (for example move from F2 to F2.8). Some lenses are good at F2.8 others at F4 and others around F5 for night time photography.
Following these steps you will get a shot with a framing you like and the longest possible exposure time without trails or optical defects. That’s your Milky Way photograph!
The Milky Way will move in the sky following Earth’s rotation as the stars move, this means you will have different compositions at different times of the night. You can get the band of our galaxy in vertical or horizontal orientation and in the middle you will have a diagonal.
The Milky Way is huge, you can attempt a panorama to get the whole band of the Milky Way in the sky. Just make sure to allow a gentle 40% overlap between shots to make things easier to your stitching software. Besides that it’s like any other panorama.