APO Sironar S 180mm f5.6 lens with Copal 1 Lens Board - 67 mm filter #21546
The Apo-Sironar-S is a lens for universal use which has been modified to provide the highest image reproduction quality. Like the Apo-Sironar-N its applications are practically limitless. Its special strengths can be seen when complex, fine structures in the adjustment range have to be reproduced.
Its field angle has been increased to 75 degrees and so permit even more generous shifts. Therefore the Apo-Sironar-S also the ideal standard lens for applications which require particularly large parallel shifts to correct the perspective. For instance, the Apo-Sironar-S 150 mm f/5.6 in the format 9 x 12 cm permits up to 10 mm more vertical or lateral shift than the equivalent Apo-Sironar-N lens.
As a result of the elimination of the secondary spectrum thanks to the use of ED glass materials with anomalous dispersion (ED = extra low dispersion), no visible colour fringing occurs even at edges with extreme contrast. In addition, the light fall-off towards the edge has been reduced for a more uniform illumination.