Many professors assign problems directly from Hecht. If they discover you have a solution manual, some may ban its use entirely. Others (wisely) encourage it, provided you cite it as a reference. The key is transparency: ask your instructor.
Many physics departments keep a copy of the ISM on reserve. You can study it inside the library but not take photos. optics hecht 5th edition solution manual
If an instructor provides access or if a student uses the manual only after sincere effort, it offers legitimate benefits: Many professors assign problems directly from Hecht