Re: [Leica] .... flatness .....

["claire" <clairetm@singnet.com.sg>]

Dear Horst S........
U replied to Mark.......

Thanks...... that made sense......

Peace
TMLee

>Mark, Flatness of field has really nothing to do with macro or not macro.
>
>Flatness of field is really not flatness of field at all, it is really some
>artificial bending of the light rays which is not present in a normal lens.
A normal
>lens just does what nature intended it to do. We humans did not like this
and
>changed its characteristics to please us.
>This change enables us to run the film in our cameras in a flat plain .
Else we
>would have to have the film plane curved to accommodate an uncorrected
lens.
>If you take a picture of  uncle bill, then his legs are at a further
distance from
>the lens, than his chest. Under normal circumstances, the focal point from
the rays
>of the chest, would be at the film plane (in the middle if the picture) but
the legs
>would be some distance in front of the film plane (at the upper edge of the
picture)
>.Now that would never do. Imagine, uncle Bill with fuzzy feed).
Unthinkable.
>Therefore the field is flattened to accommodate the  straight plane of the
film.
>
>Most the old Petzval type lenses used for movie projection had a film
flattener.
>this was another meniscus lens very close to the film.
>
>Regards, Horst Schmidt
>
>