I have an old Pentax FA135 f2.8 that is excellent in some situations. Manual focus can present challenges with today's DSLR cameras without a split prism. I avoid this lens when there's much movement on the subject. The best scenario with the manual focus is to use a tripod and back screen. That way I can enlarge the focal point 16x to fine tune the focus. If I have to use the view finder I set the camera to beep when focus peaks, get it close, then use a slight rocking motion to catch the focal point in focus.
As above comment, orange color is likely a reflection.