Nikon N55 Instruction Manual page 107

Flash shooting distance range
The distance range over which a flash can effectively provide light. Flash shooting
distance range is controlled by the amount of flash output available. Each automatic
Speed light's flash output varies from maximum duration to minimum duration. Close-up
subjects will require lower (to minimum) output, while more distant subjects will require
more light up to the maximum output.
The flash shooting distance range varies with the aperture, film speed , etc.
Flash sync speed
Shutter speed at which the entire film frame is exposed when the flash is fired in flash
shooting. The N55's flash sync speed is 1/90 sec. or slower.
Flexible Program
Flexible Program function temporarily shifts an automatically selected shutter
speed/aperture combination while maintaining correct exposure. That is, the desired
shutter speed or aperture can be selected in Auto-Multi Program.
f-number
The f-number represents the aperture value and is calculated from lens' focal length
divided by the effective aperture opening. The standard numbers for calibration are 1,
1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, etc.
The smallest f-number is called maximum aperture and the largest f-number is called
minimum aperture. Lenses with large maximum apertures (smaller f-numbers) are 'fast'
lenses that allow photographers to use faster shutter speeds in dim light. Lenses with
smaller maximum apertures (larger f-numbers) allow the use of lower shutter speeds for
available light but are also lighter and smaller than faster lenses. With some zoom
lenses, aperture varies depending on the focal length setting.
Focal length
The distance from the principal point to the focal point. In 35mm-format cameras, lenses
with a focal length of approx. 50mm are called normal or standard lenses. Lenses with a
focal length less than approx. 35mm are called wideangle lenses, and lenses with a focal
length more than approx. 85mm are called telephoto lenses. Lenses which allow the user
to continuously vary the focal length without changing focus are called zoom lenses.
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