You want the solution manual to be a scaffold that helps you build your own understanding, not a crutch that carries you. Follow this four-step protocol:

The “Advanced Physics” section at Physics Forums has thousands of threads on specific Hecht problems. Regular contributors include PhDs who will walk you through the reasoning. Post your attempt first—that’s the rule.

This is the most controversial aspect of any solution manual. Let’s be direct: Using the Optics Hecht 5th edition solution manual as a crutch to copy answers before trying problems yourself is cheating. However, using it as a learning tool after making an honest attempt is smart studying.

As you study, add your own notes to the solution manual. Circle errors if you find them. Derive alternative paths. The manual becomes your document.