Geoptik Flat Field Generator

Image calibration is a very important first step in the processing of an astronomical image, and a Geoptik Flat Field Generator is an ideal tool for this process. Light Frames are images (or a video) of a celestial object captured by the camera. Each pixel in the images will have a numeric value that includes the influences of:

• The various types of noise generated by the CCD.
• Defects in the optical system.
• CCD inhomogeneities (pixels more or less sensitive to light)
• Optical vignetting (image is darker away from the center)
• Dust on the CCD window (seen as ‘donut’ shaped spots on the image)
• Internal reflections

Example on use of calibration frames

These flat field generators are used provide even illumination surface with adjustable brightness so that you can photograph flat field frames, otherwise known as flats. When you take photos of flats, you are taking photos of the defects in your image that are caused by uneven illumination, this can then be applied to your image combined with other calibration frames (darks and flats) via software processing to correct these defects. This can be used remove dust marks (they show up like donut shadows on your image), vignetting and other sources of uneven illumination. The images bellow show the effect of calibration frames with real data. You can clearly see the effect of dust particles on the image.