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
Double School House Number 6 Double School House Number 6 Double School House Number 6 is a historic school house located in Queenstown, in Queen Anne's County, Maryland, United States. The double school house was built after a large fire in Queenstown. The property was purchased by school trustees James Masey and his wife, in 1834. As was common at the time, the building featured two separate entrances for boys and girls. In 1874, a larger school house was built on Del Rhodes Avenue, to serve the community of 250 residents. The school was moved to a new alignment and converted to a private residence