Panasonic Lumix DMC-FZ200 User Manual page 42

Crop Factor - the crop factor is a multiplier number which is the ratio of
the width of the sensor compared to that of a "full frame" 35mm sensor.
The 1/2.3 inch sensor has a crop factor of 5.6x based on 35/6.3
The FZ200 Lens
Aperture or f-stop - the aperture of the lens is the component which is
used to control the amount of light reaching the sensor.
The FZ200 has an aperture range of F2.8 to F8. The aperture, or "f- stop"
number is mathematically the result of lens focal length / the diameter of
the aperture (hole size of the diaphragm blades).
With each increase in the f-stop number (i.e. we go from a smaller
number to a larger one, say F4 to F5.6) we half the amount of light
reaching the sensor.
In the next table I show the f-stops with the whole f-stop values in red
and the 1/3 f-stops in blue. So we have a 4 stop f-stop range or 8 times
exposure difference.
Note the bigger the f-stop number, the smaller the size of the aperture.
So "wide open" the lens is at f2.8 and fully closed it is at F8.
There is a practical limit to how small the aperture can be before it starts
to degrade the image through a phenomenon called "diffraction".
The smaller the lens diameter and the tighter the pixels are together on
the sensor, the sooner this limit is reached. Interestingly the
mathematical calculation results in a value of f4 in the case of the
FZ200, where in something like a Canon FX sensor DSLR it is F22.
F2.8 F3.2 F3.5
bigger
This explains the notation on the camera lens.
The 4.5mm to 108 mm markings refer to the
real focal length of this lens which equates to
25mm at the wide angle position and at the
full zoom 600mm. Note the 1:2.8 refers to the
constant aperture over the entire zoom range,
although you can select up to F8. This makes
this one of the most outstanding features of
the camera. No other current bridge camera
can match this lens performance, optically.
F4 F4.5 F5 F5.6 F6.3 F7.1
smaller
F8
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