Archived posting to the Leica Users Group, 1998/07/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
>From: Alex Hurst <corkflor@iol.ie>
>Date: Wed, 29 Jul 1998 12:36:53 +0100
>Subject: [Leica] 2x extender R disappointment
>
>Hi LUGnuts
>
>Tried using my Leitz 2x SL/SL2 extender to turn my 90/2 into a 180/4 on
>the cheap.
>
>Quite frankly, the results were appalling. Soft focus and washed out
>colour. Nothing wrong with the 90/2, as shots taken before and afterward=
s
>with just the prime lens were tack sharp and rich in colour.
>
>I can't believe that Leitz would produce an extender this bad, so there
>must be something wrong with it (or with the way I'm using it).
>
>1) Anyone else had any bad experiences with Leitz 2x extenders?
>
>2) If it needs checking out on an optical test bench, who's the best per=
son
>to send it to? John van Stelten?
>
>TIA
>
>Slan
>
>Alex
Comment : remember the converter's law :when you use a 2X-extender, apo o=
r
not, Leica or not, you double the size of the image and you divide by two
the resolution of the lens.
The summicron 2/90, at full aperture, has a good contrast but the
resolution is only "good"(center), "fair" (edge)according to the french
review "Chasseur d'images".With the converter, at f:4, you will have
respectively "fair", "poor".
On the contrary, with the apo 3.4/180 ("excellent", "very good" at full
aperture) and the extender, you have a 6.8/360 "very good", "good". The
result of this combo is quite similar to a 6.8/400 or a 4.8/350 (see Leic=
a
foto n=B07/1981 for a test of the extender with the apo 180).
My conclusion : under 180mm and/or with non apo lenses, the game isn't
worth the candle as we say in french.
Dominique