I never owned a Casio, but I had 2 Nikon Coolpixes. If, like the Coolpixes, your Casio has a zoom function, then the following information should work for you: If you by a fixed-focal length tele, like the EagleEye Optic Zoom, then you will have the zoom that your camera provides, but you may discover some vignetting at the wide angle end. If the optics of your camera are sharp, and the you buy a good quality tele lens, then your images should stay pretty sharp. The autofocus worked with the tele on my cams, but n ot quite as well as it did without the tele; it hunted more. I hope this helps. Sue