>1. It seems that this 1.7x teleconverter will not increase a lens' f-stop.
>How is this possible?
It is not.
>If I remember the B-300 is about 80mm in diameter
80 mm is the the outer diameter of the B-300 lens, the front lens element
diameter is barely 70mm.
I have done some tests with an OM-4 with a 135 mm f2.8 Zuiko and the B-300, and
I got almost exactly 1 stop less speed.
So the combo looks more like 230mm f/4.
I also have a Kiron MC7 2x teleconverter, which goes between the lens and the
body. I find it much more convenient to "click" this converter between the lens
and the body, i.s.o. screwing the B-300 on front of the lens. It is also far
less bulky, and you get a 270mm, but at f/5.6.
Also consider that you cannot mount any screw-in filters or sun-shades on the
B-300.
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Wim Verheyen, Houthalen, Belgium, wimwim@xxxxxxxxxxxxxxxx
The Aemit modular analog home, The Kurzweil K2000/K2500 Atomium
http://gallery.uunet.be/wimwim/
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