I have the Ilford Elmo FP projector for Standard 8. The lens is the Elmo f1:1.4 18 mm. The lens is mounted in a fixing that screws to the main body. There is a focus knob on the side of this housing that moves the lens in or out to focus. The front is an aluminium barrel like you have with lens details at the front and black inside. This part unscrews, leaving the optical parts in the focus housing. I suspect it comes off to allow cleaning of the front element. You would need to unscrew the focus housing from the body to release the actual lens. It sounds lik you have an accessory zoom lens, but missing the lens itself. I have some old cine literature. I will look for a picture of the FP-C projector. Alex