Hi, i have a simple optical system composed of: 1. objective with 50 mm focal lenght 2. CCD camera that can not be mounted behind the objective, for mechanical reasons... it can only be mounted 1-2 cm far behind the objective. So i need to "translate" the focal point of the objective 1-2 cm behind the ojcetive original focal point. How can i do this?? Have i two use one or at least two lenses? Thanks in advance!!!