Here are some common terms in astrophotography:

A

  • Aperture: The diameter of a telescope’s primary lens or mirror, which determines the amount of light it can gather. Larger apertures allow for brighter and more detailed images.
  • Auto-guiding: The process of using a guide scope and camera to keep the telescope precisely aligned on a target, essential for long exposures.

B

  • Bahtinov Mask: A focusing aid that creates diffraction spikes around a bright star, making it easier to achieve precise focus.
  • Barlow Lens: An accessory that increases the focal length of a telescope, often by 2x or 3x, which magnifies the view of planets and other celestial objects.

C

  • Chromatic Aberration: Color distortion caused by lenses that do not focus all colors to the same point, common in lower-end refractors.
  • Collimation: The process of aligning a telescope’s optical elements (mirrors or lenses) to ensure clear and sharp images.
  • Coma: An optical aberration that makes stars appear distorted near the edges of the field of view, especially in reflecting telescopes.

D

  • Dark Frame: A calibration image taken with the camera’s shutter closed to record sensor noise, which is then subtracted from the final image to improve quality.
  • Declination (DEC): The celestial equivalent of latitude, indicating how far an object is above or below the celestial equator.
  • Deep Sky Objects (DSOs): Objects outside our solar system, such as galaxies, nebulae, and star clusters.
  • Diffraction Spike: A pattern seen around bright stars caused by the telescope’s support structure, common in Newtonian and SCT telescopes.

E

  • Equatorial Mount: A type of telescope mount that tracks celestial objects by aligning one axis with the Earth’s rotation, helpful for astrophotography.
  • Exposure: The amount of light allowed to reach the camera sensor, controlled by the shutter speed. Longer exposures are typically required for deep-sky objects.

F

  • Field of View (FOV): The amount of sky visible through a telescope or camera setup, which depends on the focal length and sensor size.
  • Flat Frame: A calibration image taken with the camera’s shutter open, to record sensor noise, which is then factored into the final image to improve quality.
  • Focal Length: The distance over which light is brought to focus, affecting the magnification and field of view. Longer focal lengths are used for capturing planets in detail.
  • Frame Rate: The number of images or frames captured per second when recording video, relevant for planetary photography.

G

  • Guiding: The use of a separate camera and scope (or off-axis guider) to make corrections for accurate tracking, essential for long-exposure astrophotography.
  • Gain: In a camera, the setting that controls how much the sensor amplifies the light signal, similar to ISO in photography.

H

  • Histogram: A graphical representation of the brightness levels in an image, helpful for assessing exposure and contrast in astrophotography.

I

  • ISO (gain): The sensitivity of the camera sensor to light. Higher ISO or gain settings capture fainter details but also increase noise.

L

  • Light Pollution: Artificial light from urban areas that interferes with observations. Light pollution filters are used to reduce its effects in images.
  • Lucky Imaging: A technique used to capture multiple frames in planetary imaging and then stack the best ones to reduce atmospheric distortion.

M

  • Magnification: The perceived size of an object in the viewfinder, determined by the telescope’s focal length and the eyepiece or camera used.

N

  • Noise: Random variations in brightness and color that appear in images, often more visible at higher gain settings or in longer exposures.

O

  • Opposition: When a planet is opposite the Sun in the sky, making it closest to Earth and often at its brightest and largest appearance.
  • Off-Axis Guider (OAG): A device that uses a small prism to redirect a portion of the telescope’s field of view for guiding without needing a separate guide scope.

P

  • Polar Alignment: The process of aligning an equatorial mount’s axis with the North or South celestial pole, critical for accurate tracking.
  • Post-Processing: The editing and enhancement of images in software after they are captured, including steps like stacking, color correction, and sharpening.

R

  • Resolution: The ability of a telescope and camera to distinguish fine details. Higher resolution enables clearer images of planets and other small celestial objects.
  • Right Ascension (RA): The celestial equivalent of longitude, indicating how far an object is along the celestial equator.
  • RegiStax: Popular software for stacking and sharpening images, especially used in planetary astrophotography.

S

  • Seeing: A term that describes the steadiness of the atmosphere. Good seeing conditions allow for sharper, clearer images with less distortion.
  • Sensor: The part of the camera that captures light. Larger sensors often allow for wider fields of view and greater sensitivity.
  • Stacking: Combining multiple images to improve signal-to-noise ratio, often used in both deep-sky and planetary imaging.
  • Stellarium: A free planetarium software that shows celestial objects’ positions and helps plan astrophotography sessions.

T

  • Tracking: The ability of a mount to follow celestial objects across the sky, crucial for long exposures to prevent star trails.
  • Transparency: Refers to the clarity of the sky, affected by factors like haze, clouds, and humidity. High transparency is ideal for imaging faint objects.

W

  • Wavelets: A processing technique used in software like RegiStax to enhance fine details, particularly useful for bringing out textures on planets.
  • White Balance: A camera setting that adjusts color tones to match natural light, which can be adjusted during or after capturing images.