F-number lengths. Therefore, reduced–depth-of-field effects will require smaller f-numbers when using small-format cameras than when using larger-format cameras. Image sharpness is related to f/number through two different optical effects: aberration, due to imperfect lens design, and diffraction which is due to the wave nature of light. The blur optimal f-stop varies with the lens design. For modern standard lenses having 6 or 7 elements, the sharpest image is often obtained around 5.6–8, while for older standard lenses having only 4 elements (Tessar formula) stopping to 11 will give the sharpest image. The larger number of elements in modern lenses allow the
Adler Standard 6 and, in the early models, engines that lasted only for about 17,000 km (11,500 miles). However, the Adler technicians worked on what turned out to be teething troubles, and soon the Adler Standard 6 became a favourite with the German upper middle class and with taxi operators. Following its motor show launch in October 1926, volume production of the Adler Standard 6 got under way during the early part of 1927. The six cylinder side-valve 2,540 cc engine drove the rear wheels through a three speed gear box and provided a claimed maximum output of at 3,000 rpm. The figures