Mark Erickson wrote: > > Bob wrote: > >This has to be baloney. Light *has* to strike the sensor at an oblique > angle > >or an image will not be formed! Only light along the axis of the lens will > >be perpendicular to the array, and of this light, only the ray on axis will > >be perpendicular. > > Turns out that the light doesn't have to "strike the sensor at an oblique > angle" to form an image.
Turns out that in a practical world of consumer photography, it does. If the object you're photographing is any larger than about 2", it does. Read this excerpt form that first site below: "A telecentric lens "sees" a cylindrical tube of space of diameter equal to that of the front lens element. It is limited to photographing objects whose lateral dimensions do not exceed the diameter of the lens." The use for such a lens is so limited, it's pertinence in this discussion is relegated to merely one of a curiosity. keith whaley > Check out these links on "telecentric" lenses: > > http://www.lhup.edu/~dsimanek/3d/telecent.htm > > http://www.edmundoptics.com/techsupport/DisplayArticle.cfm?articleid=261 > > In the bigger picture, once lens designs become significantly complicated, > statements like, "Light *has* to strike the sensor at an oblique angle > or an image will not be formed" don't necessarily apply. > > --Mark
