Parts of a camera - the lens

Here are some view of the lens on how it focuses. I have two lenses here, one is a Nikon Nikkor 55mm lens and another is a Canon 35-80mm lens.

Here is the Nikon lens first.
I am showing this lens retracted and extended. You might think that when the lens is extended that it is zooming. But there is no zoom in this lens. Extending the lens sets the focus. In older lenses, to adjust the focus, you the lens barrel extends. New lenses have internal focusing mechanisms so the barrel doesn't extend. All the extension and retraction is done within the lens. This makes the lens lighter and smaller.

Here is the Canon lens.


This lens is a zoom lens. I'm showing this lens at 35mm, 50mm and 80mm settings. This lens has an internal focusing mechanism so the barrel doesn't extend to focus. It only extends to zoom in or out. This lens is made of plastic as well so this lens is half the weight of the Nikon lens above.

Another difference between these two lenses is that the Nikon lens is completely manual. There is no autofocus. The Canon lens has autofocus, so you don't need to turn the lens to focus although there is a manual setting.

Don't you just love technology?