1 
THE (\JElil LüILD E4 AUTCFCCUSING ENLARGER-RECTIFIER 
by Robert Scholl 
UILD HEERBRUGG LTD 
In the development of the new Uild E4 Enlarger-Rectifier, good use 
has been made of the knowledge gained from practical experience 
with the Wild UG1 Enlarger and the Uild E3 Enlarger-Rectifier. Since 
the basic construction of the E3 has proved entirely sound, there 
was no reason to change it. The elements for control of the auto 
matic sharp focusing have, however, been simplified and in addition 
several new features have been provided on the E4 so as to make 
its operation easier. 
Like its predecessor, the E4 belongs to that group of rectifiers 
having a vertical optical axis and a projection table rotatable 
about two axes with a horizontal zero position. The five degrees 
of freedom of the instrument, namely the enlargement U, the two 
table tilts/3 about 
about the x axis and the 
made on a horizontal plane or on one that is inclined in space. 
Since all the above-mentioned movements are provided with scales, 
the E4 can also be used for rectification using given values, e.g. 
data obtained from measurements on horizon camera pictures or 
from Autographs. 
The ranges decided upon are as follows: 
for the enlargement V, 0.8x to 7x 
for the table tilts , +15^ each 
' y 7 - 
0 sin U), where f is the focal length 
f that of the aerial camera, one can 
c 7 
From the equation sin/° = 
of the rectifier lens and 
compute the largest nadir distances V? with which rectification in 
a single step is still possible. The maximum nadir distances for 
the most customary camera focal lengths f are listed in Table I. 
It is interesting to note that the values of the former in grades 
correspond to those of the latter in centimeters: