>
>
> The B-300 was designed to be used on the iS-300 / iS-3 at 180mm; there was
> a possibility/probability of vignetting at shorter focal lengths. It has a
> 55mm thread, so would best fit something like the 200mm f4, 65-200/f4,
> 50-250/f5, or 85-250/f5.
> In theory it has the advantage of a normal converter that there is no light
> loss; disadvantage is that it hangs off the front of the lens quite a
> bit...
>
> Roger Key
>
>
>
> Brian Swale wrote:
>
> Hi,
>
> Can somebody please remind me; what can a Olympus B-300 (B300)
> Teleconverter 1.7X Tele be used for with the OM / Zuiko system? I know it
> is
> designed for another series.
>
> Brian
It was designed for a front aperture size of 180mm/5.6 = 32mm, so it
will probably vignette on anything more than that. I tried it on a
65-200, and it vignetted at all focal lengths at the viewing aperture
of f/4. Even though 65mm/4 is less than 32mm, I think the front
aperture moves laterally on the front element, leading to the vignetting.
Stopping down should help with longer focal lengths, but that would
defeat the goal of not losing light.
Paul Farrar
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