on 1/14/02 6:03 AM, William Clark at wclark@xxxxxxx wrote:
> Hey all,
>
> I have been thinking of picking up a B-300. Has a good reputation.
> I have a couple of questions though.
>
> 1. It seems that this 1.7x teleconverter will not increase a lens' f-stop.
> How is this possible?
>
> 2. If I put it on top of my 135 2.8, I will get a 230 2.8 (if 1 about is
> true). What will be the performance of such a setup when compared to the
> 200 f4. I thought this setup would be good for astrophotography.
>
> Thanks!!!
> -Bill
>
This will fit and work, but it seems to meter about 1/2 stop slower than
2.8... still pretty good for the focal length. FWIW, it also fits the
100/2.0 and yields about a 170/2.5 (I think). B-300 thread diameter is 55mm.
so it would also fit the 200/4.0, I suppose you'd get about a 340/5.6 then.
Might as well use the 300/4.5 instead. Meter readings with one of my OM-4's
so probably within about 1/3 stop...
--
Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
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