The 5 x 9 inch size of a lens pouch can be limiting when it comes to accommodating all sizes and shapes of lenses. If the lens is too large or has an unusual shape, it may not fit inside the pouch. It's important to make sure that whatever type of lens you are buying fits securely within the pouch before you purchase it. Additionally, some types of lenses require special care for storage so be sure to read up on any instructions provided by manufacturers if necessary in order to keep your lens safe from damage for years to come.