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RE: [OM] Olympus 1.7X B-300 converter (was: Ken's new IS3)

Subject: RE: [OM] Olympus 1.7X B-300 converter (was: Ken's new IS3)
From: "Per Nordenberg" <per.nordenberg@xxxxxxxxxx>
Date: Tue, 17 Feb 1998 18:15:49 +0100
-----Ursprungligt meddelande-----
Från: Frank van Lindert <lindertv@xxxxxxx>
Till: olympus@xxxxxxxxxxxxxxx <olympus@xxxxxxxxxxxxxxx>
Datum: den 17 februari 1998 15:37
Ämne: Re: [OM] Olympus 1.7X B-300 converter (was: Ken's new IS3)


>I missed the earlier discussion, and certainly didn't take part in it.


It was at least a year ago I think in the old list.


>Why would it be difficult to measure the lens speed, or aperture?
>BTW, I mentioned the figure to show that this was a good performance -
>only 10 percent speed loss. But let me try to explain what I did.
>
>With a normal 1.7 teleconverter, the 200/4 would have changed into
>a 340/6.8. Olympus (seconded by you) claims that this B-300 converts
>it into a 340/4.0... or at least that is how I translate the figures
>from the instruction leaflet which strictly spoken apply for the IS3
>only. 
>I measured (through the lens with an OM-4T and checking values with a
>handheld meter) that this was not completely true for the OM setup I
>used.
>Focusing on a large brick wall magnification was indeed 1.7 times as
>high as with the plain 200 (just counting numbers of visible bricks).
>But keeping the - apparent - aperture at 4.0 the needed exposure time
>rose slightly, from 1/250 to about 1/225. (I call it apparent
>aperture, because the 200 was still on the camera, and it was the
>aperture mechanism of this lens that was used in metering, not taking
>into account the influence of the teleconverter).
>I concluded that the effective maximum aperture of the combination had
>become somewhat smaller, from the original 4.0 to (about) 4.5.... and
>I think this is a beautiful performance, compared to the 6.8 you would
>have expected with ordinary converters. Maybe the increase is so small
>that Olympus has decided to call it 'without change ...' and
>considered the scale being logarithmic this may be justified.
>
>On the IS3, in aperture priority mode, you can also see the needed
>exposure time becoming slightly longer when putting the extender on.
>
>Please correct me if I did something wrong here. But I think that we
>say basically the same thing: the maximum aperture (and consequently
>the speed of the lens) remains almost constant.
>

I agree. Ever since I learned about this I´ve always thought there was some 
loss of light, but not nearly as much as with ordinary converters. Close focus 
distance is much worse with the converter attached though, but I suppose one 
can live with that. 

BTW, is that really an IS-3 that you have? I thought they were called IS-3000 
all over Europe (incl. Holland). Mine was bought in Dubai and they had 4-digit 
numbers even there. I sure hope that something happens with the IS-3/IS-3000 
soon like an update or a small improvement. Otherwise it will probably be 
outdated before the turn of the century/millenium and taken out of production, 
and we will have nothing else in the IS line than the fancy but inadequate 
IS-20/IS-200. IS-3 was after all released as early as 1990. 

>To paraphrase some Guy known to us all: Ah! I do have a beautiful
>65-200 in stock. And a 200 as well! Please email if interested ;-)
>
>Best wishes - Frank.
>


If he´d have a 65-200 in mint cond for $150 I wouldn´t mind being notified 
about it ;-)

Best regards,
Per Nordenberg


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