Paul Tarnavsky

Hi Everyone, I recently purchased a Bell & Howell 240 (single lens) off ebay. The camera came with a B&H 20mm f/2.5 20mm Comat lens and I'm confused about how this lens works. Here's a description and photo of the lens: The front of the lens reads various frames per second. The middle part of the lens reads "film 10 32 index" The base of the lens reads various stops from 2.5 - 16 Here are my questions: 1. Could someone please tell me what the middle part (film index) does? It appears to rotate independently of the base and front ends of the lens when you pull up. Also, why does it only give two numbers, a 10 and 32? What do those numbers represent? Are they supposed to line up some how with the frames per second above it? 2. Does the middle part somehow work in conjunction with the front end reading various fps? Supposing I wanted to film in 24 fps, what do I do to the lens to achieve this? I'm very very new to film. I purchased the camera as a learning tool and cant wait to start shooting. I'd greatly appreciate anyone's help in this matter. -Paul