Monochromatic aberrations due to various optical elements of Cassegrain telescopes cause distortions and imperfections in acquired images. Hence, degrading their spatial resolution and overall quality. In this paper, the effects of three types of monochromatic aberrations, including coma, and astigmatism, spherical aberrations, of a Cassegrain telescope are comprehensively characterized. Zernike polynomials are employed to express and simulate these aberrations and to systematically analyse their impact on image quality. Quantitative metrics such as Mean Square Error (MSE), Peak-Signal to Noise Ratio (PSNR), and structural similarity index (SSIM) are utilized to assess the deviations introduced by aberrations compared to a diffraction-limited optical system. By applying these aberrations to spoke target image, this research contributes valuable insights into the specific context of Cassegrain telescopes. The findings provide a foundational understanding of aberration effects on high-resolution images to compromise an enhanced optical design.