Astrophotography

Many people think that only those who can afford professional photography equipment can capture stunning images of the night sky, but in fact it is possible for many amateur photographers to capture the heavens in all their glory. While it was once necessary to travel into the remote wilderness trailing an array of expensive cameras, filters and tripods, these days special filters and new technology makes it possible to capture vivid images of the night sky in less than optimal conditions.

There are many techniques photographers use to capture those images, and the learning curve for astrophotography can be quite steep for those new to the field. Photographing the heavens presents many challenges not encountered in other photographic endeavors, and it can take some time, patience and creativity to overcome those unique challenges.

In order to overcome the challenges associated with astrophotography it is important to understand just what those challenges are. Photographing celestial objects is quite different from photographing landscapes, people and other subjects. Some of the most significant obstacles faced by newcomers to astrophotography include:

• In order to be successful photographers will need to be able to deal with extremely low light conditions. Any photographer who has ever shot in near darkness understands how challenging a lack of light can be.
• In many cases those photographing celestial objects may not be able to see their subjects with the naked eye. Photographing objects that require the use of a telescope to discern can be challenging to say the least.
• It can be difficult to discern the color spectrum of the objects being captured. Some celestial objects will be close to the infrared spectrum, and may require the use of special filters to photograph properly.
• Astrophotography is further complicated by the fact that the earth is constantly rotating. The location of the objects being recorded are constantly changing in relation to the position of the earth. In order to be successful at astrophotography photographers will need to compensate for the earth’s rotation.
• Telescope mounts and camera tracking platforms can be used to compensate for the movement of celestial objects, but they can be expensive to buy and difficult to set up.
• Astrophotography requires long exposure times, and these lengthy exposures can produce excessive noise on many digital cameras. Using active cooling can help reduce the problems associated with long exposures.

Astrophotography in the Digital Age

Many amateur and professional astronomers have abandoned old fashioned film cameras in favor of new digital technology, and digital cameras can produce some excellent photos of the heavens. One advantage of digital astrophotography is that the CCDs in digital cameras are generally quite sensitive, and of course there is no expensive film to buy. On the downside, digital cameras have a much reduced field of view, and photographers will need to compensate for this reduction.

In order to overcome the challenges of low light conditions in astrophotography, digital photographers rely on a number of techniques and pieces of equipment. Some of the modifications photographers can make to their digital cameras include:

• Cryogenic cooling – this cooling will help to reduce thermal noise that could ruin an otherwise good photograph
• Biasing
• Flat field correction
• A good self timer
• Manual exposure control
• A quality tripod

In addition to the camera specific features, there are a number of software manipulations that can make photographs of the heavens more attractive as useful. The images captured by digital cameras can be adjusted to increase contrast and brighten color, and a number of special effects can be used as well. Filters can make a big difference in the finished product, allowing users to filter out any thermal noise or light pollution that may be present.

There is no doubt that photographing the heavens presents more of a challenge than taking a snapshot of a nearby hillside. Even so, modern technology has helped both amateur and professional photographers to capture their favorite images of the night sky. Astrophotography can be a fun and rewarding hobby for any stargazer, and digital technology has made it easier than ever to get started.