on 6/05/2003 13:39, Dizel at webmaster@xxxxxxxx wrote:
> The f-stop is a geometric relationship between focal length and effective
> aperture and does not take into account light loss within a lens.
> Each air to glass surface reflects some light. So real 'opening', called
> t/stop is different than f/stop. This difference depends of lens construction
> (number of elements, coatings used..) and usually is NOT given.
> Only some companies, most notably Kiron, callibrated their
> diaphragm scale in t/stops.
Very enlightening explanation ;-)
> Type 'Bokeh' into web searcher
> (e.g. Google). then you will be enlighened ;)
>From Japanese ! I was accustomed to the old fashioned expression "depht of
field" but it seems bokeh takes into account more variables... Having read
the thread and watched the bokeh chapter at TOPE I still could not
understand how a lens could have a good/bad depht of field by itself, I
understood it would rather refer to the ability of the photographer to
compose a picture taking into account all the components in the
fore/background.
With this new enlightment, I would add to my previous post that my formerly
disregarded 28mm F2.8 has good bokeh at full aperture.
Thanks Dizel and Jim for your replies.
Fernando.
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