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
On the 6 received praise for its versatility, described as "seductive" and "sultry" by critics. Some found the album's material and vocals underwhelming, however. The album was successful on the charts, reaching the top ten in the United States and other countries (dispelling preconceptions that it could ruin her career). "On the 6" went on to sell nearly three million copies in the United States (certified triple platinum by the Recording Industry Association of America) and over 10 million copies worldwide. "On the 6" produced five singles, most of which were commercially successful. "If You Had My Love" peaked at number one in