Astrophotography

The art of capturing astronomical images using a camera is called astrophotography. Today, all astronomical imaging use digital sensors known as CCD and CMOS cameras. Simple astrophotography can be conducted using a camera with a wide-field lens mounted on a tripod. Exposure time must be small since the Earth’s rotation causes celestial objects to move. Longer exposures using a camera and lens can be conducted with the camera mounted on a device that rotates at the same rate as the Earth. A simple method is to attach a camera and lens piggyback on a telescope system that can track the stars. Afocal photography involves pointing a camera lens at the eyepiece of a telescope to capture the eyepiece image. Prime focus photography is when a camera without a lens is attached to a telescope in place of the eyepiece. Thus, the telescope becomes the lens for the camera, producing high-magnification images. Digital images must be calibrated using dark frames, flat-field frames, and bias frames.