Astrophotography means taking pictures of objects in the night sky such the moon, stars and distant galaxies or constellations. Since these objects are very far away, and the light from them tends to be very faint, astrophotography is more difficult in some ways than other types of photography.
What You Need
Your equipment depends a great deal on what you are trying to photograph and the level of detail you want to achieve. If you want to photograph the full range of possibilities you should have all of the following:
- Camera with manual shutter control and a wide aperture
- Tripod mount
- Computerized altazimuth mount
- Equatorial motorized mount
- Camera remote control
Using a Simple Digital Camera (Beginners)
One of the best things about astrophotography is that just about anyone with a digital camera can take some simple but beautiful shots of the night sky without any sort of fancy equipment or complex technical know-how. If you are just starting out with this kind of photography, or you aren’t able to buy more expensive equipment, then just use the following tips to take good shots.
It is important that the camera be manually set for taking pictures of faint and distant objects. This means keeping the exposure time as along as possible and having a wide aperture. There are a few other digital camera tricks that can help as well. These settings can usually be found in the camera’s menu.
Digital cameras also have a sensitivity multiplier called the ISO setting. This is another way to capture more light and details. The trick here is to set the ISO as high as possible for the camera, and then go back and filter out any problems on the computer afterward.
Be sure to keep the auto-focus turned off. Standard digital cameras are not programmed to focus on such distant and faint objects, and it is very unlikely that auto-focus will get it right. Then you can manually focus the camera at its farthest focus setting.
Be sure to take steady shots either with a tripod mount or using some other anchor for support. Any movement in the camera will turn a long-exposure shot into a blurry mess. Keep in mind that with these extreme settings, many initial pictures may not look that great. Most shots done this way will require some tweaking on the computer before being presentable, but any digital photographer expects this. There is always computer work to be done afterward.
Your final pictures may also have star trails. This is a product of long-exposure shots done without the use of a motorized mount. Since the stars move even in the few seconds of exposure, their image elongates into a trail. This can be beautiful in its own right for some shots.
Using a Telescope and Mount (Advanced)
Those who truly wish to capture the glory of distant stars will want to use a telescope and motorized mount. This allows detailed images to be taken of the moon surface, as well as much better images of planets and distant objects. The motorized mount is important to compensate for the Earth’s rotation and prevent very long star trails or blurry images.
Hooking the camera to the telescope depends on the type of camera you have. Many cameras can be hooked to the telescope but still use their own lens, essentially seeing through the scope much like a person would. DSLR cameras and other advanced cameras may be able to hook directly into the telescope and use the telescope’s lens as their own. The direct hookup method is more advanced and will result in better pictures. This can be done with a few simple accessories, namely a T-mount and 2-inch or similar adapter. Be sure to get accessories that match your camera model and telescope size, since they are usually brand-specific.
Keeping the camera mounted on a motorized altazimuth mount or an even more advanced equatorial mount is very important for telescoped pictures. These mounts both stabilize the camera and keep it moving at about the speed of the Earth’s rotation. This allows the camera to stay steady on distant objects for very long exposure times. An altazimuth mount provides enough adjustment for about 30 second exposures. Longer exposures required equatorial mounts.
Most cameras can be manually set for an exposure time up to 30 seconds. Longer exposures will require a few extra tricks. After 30 seconds, the next highest setting is called bulb. The bulb setting means that the camera will keep its shutter open as long as you hold down the button. The problem is that you can’t do this while the camera is hooked up to the motorized mount and telescope. Your next accessory will be a remote control for the camera. Most brands have these to allow you to manipulate the camera shutter and settings without touching it.
Choosing the Right Location
As with all photography, location is critical to getting the best pictures. The most important factor for astrophotos is light pollution. Longer exposure times mean that even the smallest amount of light pollution can ruin the photo. You will not be able to take good pictures anywhere near a town or city, so the best astrophotographers travel as far as they can from civilization. Also be sure there is not a busy roadway nearby.
By keeping these simple tips and procedures in mind, you are well on your way to taking amazing shots of the night sky.