QHYCCD QHY10 User Manual

Contents

QHYCCD QHY10 User Manual Manual pdf 21 page image

39 40Partial Cropped DARK Image (D)DARK image which be calibrated by BIAS Field （D-B）Capture FLAT ImageFLAT image can be used to rectify the problem ofthe center light but the edge dark which caused bythe vignette of optical system. It also can becorrected the problem due to some small dust onthe CCD sensor glass surface.Flat-field calibration method is this: you needuniform luminous lightbox. The lightbox will beplaced in front of the telescope. You would set theappropriate exposure time, then continuous shoot10-50 frame flat-field images. Save and overlaythese images to form a FLAT Master image, savethe image.To obtain an accurate flat-field calibration, Pleasenote the following matters:You have to take immediately flat-field imagesbefore the shooting or after finishing shooting.Like do this in order to avoid dismantling thedevice, dust on CCD surface and vibration of CCDcause the change of location. The scope ofexposure is better for 30% of the maximumdynamic range , which means you have gotten20000-30000 pixel of flat-field image.Images of BIAS Master, DARK Master and FLATMaster will be calibration data as image post-processing of the captured images .WWW.QHYCCD.COM

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