Dear Just Curious, You should see your doctor about these compulsive posts.
However, I would venture to guess that something like the 28-70 is basically a 70mm lens that has a variable retrofocus-converter to dial in the zoom focus length making it physically longer at shorter focal lengths. While the typical tele-zoom has a variable tele-converter to change the focus length.
Then there are the internal focusing zooms which change focal length with distance. And the... Oh, well, you get it, there are lots of ways of achieving the same thing.
graywolf http://www.graywolfphoto.com http://webpages.charter.net/graywolf "Idiot Proof" <==> "Expert Proof" ----------------------------------- Don Sanderson wrote:
Maybe someone can enlighten me. Some zoom lenses are physically longest at their longest focal length, such as the FA24-90. Others, like the FA28-70/4 AL are physically shortest at their longest FL. Does anyone know why this is, and what advantage or disadvantage each design has? I get along much better with short physical length lenses simply because a bit of movement at the camera isn't amplified so much at the end of the lens. Just curious. Don
