On Gio, 28 mag 1998 6:01, Winsor Crosby <mailto:wincros@xxxxxxx> wrote:
> have a question for you knowledgeable people on this list. Olympus
>probably takes the prize for assigning odd FStop numbers to the widest
>aperture on their lenses. I am never quite sure, since FStops are not
>linear or arithmetic, how much more light I am letting in wide open than
>the nearest true FStop. What is the relationship between F1.2 and F1.4,
>F1.8 and F2, F3/5 or F3.6 and F4, F4.5 and F5.6, F5 and F5.6, F6.3 and F8,
>F6.5 and F8? Did I leave any out? Are these odd F-numbers 1/3, 1/2, 2/3 of
>a stop wider or are they essentially the same?
>
>Winsor
It is a fact that every manifacturer else than Olympus would have called a
lens 3.5 instead of 3.6. Another odd one is Tokina with its 2.6-2.8 lens
(instead of the usual 2.5 value). And we remember the 0.95 Canon lens.
There are marketing reasons for all this, I think.
Marco
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