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 By 1930 Adler had produced 6,533 of their Standard 6Ns. The Standard 6A and 6S had been added to the range by the end of 1928. They still featured straight six engines, but the bore was increased and the total engine size was 2,916 cc. Claimed maximum power from the 2,916 cc engine was . Apart from the cylinder bore, the engine was little changed from the 2,540 cc unit of the Standard 6N, but the compression ratio was slightly raised, and during the production run a Stromberg U1 carbureter replaced the Pallas SAD 3 carburettor which initially was carried