We constantly see photographs of space in the media snapped by advanced space telescopes, but it is surprisingly easy to capture your own pictures of the universe with fairly standard equipment you can buy "off the shelf."
Some words of caution first though: the results are limited with simple equipment but more specialist kit is needed to snap elusive deep sky treasures like galaxies and star clusters.
However, even with the most basic of equipment, you'll be surprised to see that colors -- previously unseen to the naked eye -- will leap into view when you point a camera at the night sky. It's not magic, it's science. Our eyes are poor at detecting color in low light conditions -- unlike a digital camera, which is why the multicolored glories of the sky can be revealed.
Let's start this astrophotography series with simple shots of the night sky.
The equipment for this type of shot is just a camera that can take long exposures, a sturdy tripod and some method of remotely operating the camera. Digital SLR cameras are ideal, but any camera that can take long exposures should be fine. Using this equipment it is possible to capture constellations, star trails, even meteors.
There are a few slight variations to this technique but essentially you need to fix the camera to the tripod making sure it's nice and solid, point the camera at the sky, focus on the stars (manual focus is more reliable than relying on automatic focusing) and -- *click* -- take the picture.
A method of remote shutter operation is necessary otherwise touching the shutter button on the camera body will cause shaking, which will be seen in the final picture with wiggly or blurred stars. It's possible to buy gadgets to do this or you can just place a piece of card in front of the lens while you push the shutter, let the camera shake die down, remove the card for your required exposure before putting it back before closing the shutter.
If you have a camera that has more settings available like a DSLR you will need to make sure the ISO setting is set high -- around 1600 will be good for a start (higher numbers mean more sensitive exposures, so fainter stars may be recorded). Also, make sure the lens aperture is opened wide so that it lets in as much light as possible. This will mean you'll be using a low f number such as f/2 or f/2.8, rather than something like f/16, which lets in much less light.
But you will need to experiment with the settings -- this will this determine which stars are recorded and whether the rotation of the Earth will be a noticed!
Depending on what you want to photograph, the secret is in exposure time. So how can you capture star trails, constellations and meteors?
Star trails are either the blight or the friend of the astronomical photographer. They are caused by the Earth having rotated during the period of the exposure. They can form stunning pictures if intended with foreground terrestrial objects to add extra interest but if you are trying to capture constellation shots they are less than helpful.
Exposures of the order of minutes (or hours) can yield some stunning results but also try an aperture setting around f/5.6 to reduce the incoming light a little. You can also try to fire off the flash during long exposures to light up foreground objects. Experiment and have fun.
For constellation shots, exposure times need to be short enough so that the Earth's rotation doesn't cause the stars to trail and ruin the pinpoint stars.
The length of exposure is determined by a couple of factors; the declination of the area of sky (you can use longer exposures when woking nearer the north and south celestial polar regions because the motion isn't as great as it is nearer the celestial equator) and focal length of lens in use (longer focal length lenses will magnify the sky more and therefore magnify the motion of stars across the sky, so a shorter focal length lens will allow longer exposures). It's a bit of a juggling act so don't be afraid to experiment. As a guide, try exposures around 30 seconds and you should get some good results.
If you want to capture elusive meteors, then follow the guide for star trails above, point at the sky and wait! I'm afraid a dash of luck is needed here as you never know where they will appear or when. You can guarantee you will stop the exposure at just the time when the best meteor you have ever seen appears.
It's all trial and error to find the best settings for your equipment, depending on the conditions, but persevere and using this guide as a starting point, you will start to see some good results.
In my next astrophotography guide we will look at ways to capture images of the moon and planets.