The Canon 77mm Screw-in Protection Filter can be fitted to your lens to protect the surface from scratches and dust. Because they are colorless and transparent, protective filters have no effect on the color balance of the image. 
 

• EF lens accessories help you to add quality and creativity to your images
• Filters can be used to obtain correct tones or color reproduction in difficult or unusual lighting conditions
• Filters can also change or distort light for special effects
• A neutral filter protects your valuable lens while maintaining perfect color balance
• Its multilayer coating reduces the risk of flare
• Does not alter the exposure