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
Amazon Standard Identification Number businesses in the yellow pages (on A9.com) and OpenSearch feeds. Amazon Standard Identification Number An Amazon Standard Identification Number (ASIN) is a 10-character alphanumeric unique identifier assigned by Amazon.com and its partners for product identification within the Amazon organization. ASINs were once unique worldwide, but global marketing has changed so that ASINs are only guaranteed unique within particular marketplaces. Accordingly, the same product may have several ASINs though, and different national sites may use a different ASIN for the same product. In general, ASINs are unlikely to be different between the country sites specially if they are for a class