TY - JOUR T1 - Defocusing Effect Studies in MTF of CCD Cameras Based on PSF Measuring Technique TT - JF - ijop JO - ijop VL - 9 IS - 2 UR - http://ijop.ir/article-1-203-en.html Y1 - 2015 SP - 87 EP - 92 KW - CCD KW - Cut-off Frequency KW - Defocusing KW - MTF KW - PSF. N2 - Defocusing effects in modulation transfer function (MTF) measurement of charge coupled device (CCD) cameras is the main focus of current paper. We introduce measuring Point-spread function (PSF) in order to calculate the MTF and further more we will study the shape of MTF and its cut-off frequency by adjusting the lens focusing in different locations. A collimated white light LED by broadband spectra is used as source and our results shows that the cut-off frequency is related to defocusing. M3 ER -