COMMISSION ]
Appendix to
B5
PHOTOGRAMMETRY, Vol. Xs 1084
New Photogrammetric Lenses
By L. Bertele, Heerbrugg
Lecture held at the VIII th International Congress of Photogrammetry,
Stockholm, July 1956
After having developed, in 1947 and 1948, the distorsionfree Aviotar f:4 normal angle lens of
great brightness for photogrammetric purposes, we still had three more problems to solve, i. e.
the creation of an equivalent wide angle lens, of a wide angle enlarging lens and of a super wide
———À angle lens. | will sum up the review ot all three of them in one as their development was guided
by the same principle. The train of my thaughts was the following one:
trazine
)g/m In order not to lose the general view, right from the beginning, over the many reproduction de-
fects to remove when developing a distorsionfree wide angle lens, it turned out to be useful to
start with a lens series with concentric curvatures of all lens surfaces. Any line going through
the common centre thus represents an optical axis so that, if using a spherical emulsion bearer
concentrically mounted, one obtains an angle of nearly 180° with an image quality that is not
quite good but at least absolutely uniform, this on condition that the focal distance of this sys-
tem is positive. As such an emulsion bearer is unwelcome for self-evident reasons, one must
first of all provide for a levelling of the reproduction field without introducing any distorsion
whereby one has to waive some of the concentrically disposed lens surfaces. On this base
there remains only two construction possibilities. Either the lens centre is an air sphere with a
glass cover (fig. 1) or a pure glass sphere (fig. 2) whereby the air slit provided in the glass
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Fig. 1 Fig. 2
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