We'll start out with the easiest of subjects, the Moon and Sun. They are the biggest and brightest astronomical objects close by to the Earth. Then we'll shoot some easy night-time images, star trails and constellations. Try to learn a little about the relationship between exposure and the brightness of objects recorded, including the sky background, and how the camera's meter can be fooled by small bright objects in an otherwise dark frame. For this reason, automatic exposure usually doesn't work well with astronomical images. You will want to use the camera on manual exposure most of the time. Luckily with a digital camera we can always test the exposure by trial and error and then get immediate feedback by viewing the image and histogram on the back of the camera. We'll learn that we can only expose for so long, especially under skies with light pollution, before the sky background becomes overexposed. We'll also learn that because the Earth rotates, objects appear to move across the sky, just as the Sun and Moon appear to rise in the East and set in the West., The stars, planets and other celestial objects all move across the sky also for the same reason. Because of this apparent motion, exposure length will be limited before objects become trailed. We even exploit this fact in our star trail pictures. We will also learn that with the new generation of low-noise DSLR cameras, we can record a remarkable amount of stuff in a relatively short exposure on a fixed tripod from a dark-sky site, and that some of the prettiest pictures can be taken with very simple equipment. The Learning Curve
If you have a camera, take it outside one clear night, put it on a tripod or bean bag on top of a table, use the self-timer and the longest exposure possible with the lens wide open and focused on infinity, and take a picture of some stars. It's that simple to get started. Once you have learned a little bit about astronomy and started to find your way around the sky, you can get started with some basic astrophotography. If you have a camera, no matter what kind, try some simple shots with the camera on a tripod. You can shoot the constellations, moon, brighter planets, bright comets and meteors with very simple equipment. There is a bewildering amount of equipment and advice about astrophotography around. It is very easy for a beginner to become overwhelmed. Take your time and start slow. Subscribe to an astronomy magazine like Sky & Telescope or Astronomy and read up a little. Join a local astronomy club and attend the monthly meetings. Look through some club member's telescopes at a star party. Talk to a lot of different people about the kind of astrophotography you are interested in. Many astrophotographers have definite ideas about what they think is right, but they might not necessarily be right for you. Take everything with a grain of salt. Eventually you will learn that there is a consensus about most things. When it comes to astrophotography, you can learn a tremendous amount from reading, but the best way to truly learn is by trial and error and by actually doing it yourself. That, however, doesn't mean that you have to re-invent the wheel and repeat every common mistake every time. There is also much to be learned from the accumulated wisdom of veteran astrophotographers. If you don't have a digital camera, or telescope, but want to buy one, or want to buy a better one to get started in astrophotography, please do not rush out and buy something on an impulse in a department store or camera store. There are hundreds of kinds of digital cameras and hundreds of different telescopes out there. Many of these, despite advertising claims, are not very good for the purpose of astrophotography. If you already have a digital camera and telescope, then by all means use these to get started. But you should seriously research which camera and telescope to buy before you make a purchase. I would strongly recommend joining a local astronomy club and picking the member's brains for information. I would also very highly recommend joining an internet special interest group, such as the DSLR astrophotography forum on Cloudy Nights, and learning about whatever area of astrophotography you are interested in first, before you spend any hard-earned money. In learning the craft of astrophotography, it is best to start out with the brightest astronomical objects - the Sun (properly and safely filtered), the Moon, and scenics that include the brightest planets. Then simple short time exposures with the camera on a tripod can be tried. These subjects can be taken with normal cameras and short exposures and don't require any expensive or sophisticated equipment. Over the course of several months while the beginning astrophotographer experiments and learns the basics of the hobby, they can be researching DSLR cameras, telescopes and mounts, preparing to move up a level in degree of difficulty.
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