In 1878 we find the VOIGTLÄNDER'sche institution the introduction of a portrait lens with a cemented rear lens busy, of a type possibly due to the same author is due to .
J. M. EDER tells us meanwhile (1. 126.) that after some years 1885 the manufacture of these lenses in favor of a type was abandoned in which after the process J. H. DALLMEYER's glass sequence in the hind limb was changed.
If one reduces that there (1. 122.) for a focal length of 167 mm
given radius values by dividing by 1.67 on f appr. =100 mm , these numbers can be compared with those of J. H. DALLMEYER compare specified. Now the approximate
f = 100 mm reduced radii according to J. H. DALLMEYER ( 1866 ):
and, very similarly, after FR. VOIGTLANDER (1885):
Unfortunately, not all the data are known here either, specifically the distance is missing.
In order to have a picture of this VOIGTLÄNDER type, it will suffice to visualize DALLMEYER's, Fig. 86.
In the drawing there would hardly be any other difference make noticeable the difference in curvature on surface 4 would not recognize for the so few different arrow heights
bar will be as of that the lens diameter in the first case would be 33.3mm, in the second 31.1mm.
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