Can anyone explain the numbers around the lens on an old 35mm camera?

I really dont how to use it! It's a PRACTICA PL nova1 or I. I think it is about 40 years old. Thanks for any help!Can anyone explain the numbers around the lens on an old 35mm camera?
There's a bunch of numbers on a lens.





First, there's the distance scale. This is in feet, meters, or both. When you're in focus, it's a rough estimate of how far away your subject is from the camera.





Next, you'll see a ring with numbers like 22, 16, 11, 8, 5.6, 4, etc. That's the aperture ring. This controls how much light comes through the lens.





Finally you may see these numbers repeated on the lens, on both sides of the focus line. This is what is known as a ';depth of field scale.'; For example if you're focused on a subject 10 feet away at f/11, look at the scale. Everything between the 11 on the left and the 11 on the right will be ';in focus'; when you take the photo. If you switch to 16 on the aperture at the same distance, everything between the 16 on the left and right will be in focus, etc.





Other numbers on a lens:


1) focal length, measured in mm. This determines if your lens is a wide angle (usually less than 36mm) normal (roughly 36 to 60mm) or telephoto (roughly 60mm and up)





2) filter thread size in mm





3) maximum aperture





Example: 50mm f/1.8 = 50mm focal length, maximum aperture 1.8Can anyone explain the numbers around the lens on an old 35mm camera?
Google F-stop....thats what they are.





Better yet....here ya go:





http://en.wikipedia.org/wiki/F-number





P.S: Its a pain in the butt.
google it