J
jgban
Kyocera Kid,
To me, what has always been a mystery is how come there are zooms with fixed aperture. In my ignorance, I thought the f value was the ratio between the diameter of the diaphragm and the focal length. From this standpoint (which, I acknowledge, must be wrong) it seems difficult to keep a constant f value when your zoom changes the focal length by a factor or 3 or more.
Anyone who can shed light on this specific lens design problem will be most welcome.
Juan
To me, what has always been a mystery is how come there are zooms with fixed aperture. In my ignorance, I thought the f value was the ratio between the diameter of the diaphragm and the focal length. From this standpoint (which, I acknowledge, must be wrong) it seems difficult to keep a constant f value when your zoom changes the focal length by a factor or 3 or more.
Anyone who can shed light on this specific lens design problem will be most welcome.
Juan