Abstract: An auxiliary lens holding cylinder has a main cylinder having a lens holder on one end and a camera mounting fixture on the other end and a sub-cylinder having a built-in lens for one of a variety of types of photography is coaxially removably mounted in the main cylinder. The built-in lens can be a plus type lens or a minus type lens. The main cylinder has a sub-cylinder holder mounted therein coaxial with the main cylinder, and guiding and locking grooves in the holder cooperating with a boss on the sub-cylinder for guiding the sub-cylinder into the holder and locking the sub-cylinder in the holder. A spring on the main cylinder urges the sub-cylinder into locking engagement with the guiding and locking grooves.