astrophotography

Astrophotography is the practice of capturing images of astronomical objects and phenomena with cameras and imaging sensors. It covers wide-field sky landscapes as well as deep-sky targets such as galaxies and nebulae, planetary imaging, the Moon, and the Sun. It uses long exposures or high-frame-rate video with stacking to improve signal relative to noise, often requiring careful planning and calibration.

Equipment commonly includes a stable mount with tracking, a telescope or telephoto lens, and a digital sensor (CCD/CMOS) or a DSLR/mirrorless camera. Many images use narrowband filters (for example H-alpha, OIII, SII) or color cameras with simple RGB processing. Core techniques are long exposures, frame stacking, and calibration with dark, flat, and bias frames, followed by post-processing to reveal faint detail.

Subfields include deep-sky imaging of galaxies, nebulae, and star clusters; planetary imaging with high frame rates and stacking of thousands of frames; lunar and solar imaging with appropriate safety filters; and wide-field photography of the Milky Way or meteor trails.

Planning and site selection are important due to light pollution and atmospheric conditions. Focus, accurate guiding, and dithering improve sharpness and reduce artifacts. Challenges include noise, sky glow, weather, and equipment cost; advances in sensors, automation, and software continue to expand capabilities.

Historically, early astronomical photography emerged in the 19th century with pioneers such as John William Draper and Henry Draper. Since then, digital sensors and processing software have made astrophotography accessible to hobbyists and a valuable tool for science and education.