The actual time in the air would be 5.9 hours (probably longer, since spec sheet range numbers usually are at economy settings, but speed is quoted at 75%). Two fuel stops, however, are going to add 1.5 hours (45 minutes per stop, which is conservative) for a total of 7.3 hours.
A normal lens or normal prime is a lens with a focal length about equal to the diagonal size of the film or sensor format, or that reproduces perspective that generally looks natural to a human observer under normal viewing conditions.
A lens with one convex and one concave side is convex-concave or meniscus. It is this type of lens that is most commonly used in corrective lenses. If the lens is biconvex or plano-convex, a collimated beam of light passing through the lens converges to a spot (a focus) behind the lens.hen the thickness of the lens is not much smaller than S 1 and S 2 or there are multiple lens elements (a compound lens), one must instead measure from the object and image to the principal planes of the lens.