The SVBONY MK90 features a convex meniscus lens instead of a traditional Schmidt corrector plate, enhancing contrast and eliminating the need for periodic collimation, instant readiness for stargazing; each astronomical photography telescope undergoes precise optical axis alignment before leaving the factory; 3 screws for fixation; 3 pairs of calibration screws; enjoy immediately easy to use. SV183 IR Pass filter blocks wavelengths below 670nm to enhance contrast and surface detail and reduce the effects of seeing when used in IR-LRGB imaging of the moon and planets. At these longer wavelengths, planetary images are less disturbed by wave front distortions in the atmosphere. Atmospheric seeing and distortion diminish as you move further away from visible light into the infrared, and since CCD and CMOS sensors are sensitive to IR light, imaging in the infrared will improve your results.